HomeMy WebLinkAboutA013 - October 28, 2025, Regular Meeting of the Ames City CouncilITEM #:16
DATE:10-28-25
DEPT:ADMIN
SUBJECT:BUILDING ENERGY AUDIT REPORT
COUNCIL ACTION FORM
BACKGROUND:
A key strategy established in the community-wide Climate Action Plan, accepted by
City Council in June 2023, is to integrate energy efficiency and renewable energy into
municipal buildings. These strategies not only reduce carbon emissions but also result in
long-term energy cost savings.
In November 2024, an RFP was issued involving energy auditing services at 15 City-owned
buildings. An evaluation team reviewed 10 proposals and conducted interviews. In January
2025, City Council awarded the contract to Resource Consulting Engineers, LLC (RCE), of
Ames, Iowa, in an amount not to exceed $102,600. The Electric Administration building was
later added to the original scope through a change order of $1,000.
The scope of work included the following services for 16 City-owned buildings.
Data gathering and analysis of building plans, utility bill data, and interviews with staff.
On-site facility inspections.
Detailed energy analyses.
Developing specific and impactful recommendations for energy efficiency measures
(EEMs), including capital improvement measures and changes to operations and
maintenance.
RCE's approach to the project involved three methods: energy modeling, benchmarking, and
manual calculations. A detailed energy model was generated for larger or more complex
buildings to allow for more customized results (e.g., City Hall). Benchmarking was performed
for smaller or more typical building types (e.g., Electric Administration), which allows for useful
information to be projected about energy use without the more involved and detailed energy
model. Finally, manual calculations were completed for facilities that might be difficult to fully
model and where appropriate benchmarking data was not available (e.g., Ames/ISU Ice
Arena).
Generally, recommended improvements include installation of new HVAC systems,
lighting, water heating, windows, and roof insulation. Each EEM provides detailed
information regarding capital costs and savings, including energy, emissions, cost, and simple
payback.
EEMs include fuel switching from natural gas to electricity where possible, to align with CAP
goals. Recommendations for implementation are included in the report, and for many EEMs, it
is recommended that implementation occur at the end of the useful life of the existing
equipment. Some EEMs are bundled together, where it makes logistical sense to complete
multiple projects at one building simultaneously.
The report also contains a solar feasibility assessment for five City buildings, and an electric
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vehicle charging assessment for 15 buildings. The results of the solar assessment indicate
that most City buildings would not be suitable for solar, primarily due to roof age. The Fitch
Family Indoor Aquatic Center, Schainker Plaza, and the new site of the Ames Animal Shelter
may be suitable candidates for solar. Results from the electric vehicle charging assessment
indicates adequate electric service size and demand capacity to accommodate expanded
charging at most City facilities.
This report will help prioritize projects and inform decisions related to facility planning
and investments to continue moving the City towards achieving the Climate Action
Plan goals.
Resource Consulting Engineers, LLC (RCE) will be presenting an overview of the Energy
Audit Report.
ALTERNATIVES:
1. Accept the attached City of Ames Energy Audit Report.
2. Refer this document to City staff for further information.
CITY MANAGER'S RECOMMENDED ACTION:
It should be emphasized that the Energy Audit Report is not expected to be adopted as
a formal policy document or plan. Instead, it provides information for the City to
consider as it works towards energy efficiency improvements of City buildings.
Furthermore, the report recommends that many of the energy efficiency upgrades be
considered for implementation at the end of the useful life of the existing equipment.
Accepting this report does not adopt it as a formal policy document or plan. Therefore,
it is the recommendation of the City Manager that the City Council approve Alternative No. 1
and accept the attached Building Energy Audit report.
ATTACHMENT(S):
2025-1015 City of Ames Energy Audit Report.pdf
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City of Ames Energy Audit Report
October 2025
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3City of Ames Energy Audit
Table of Contents
Introduction
Project Team 3
Executive Summary 4
Building Energy Audits 11
Energy Model Analysis
Technical Services Complex 13
City Hall 31
Ames Public Library 49
Fire Station 1 65
Benchmarking Analysis
Fire Station 3 81
Public Works and Fleet 93
Electric Distribution 105
Electric Administration 117
Homewood Golf Course Clubhouse 129
Parks and Recreation Administration 141
Airport Terminal 155
Manual Calculation Analysis
CyRide Transit 167
Ames Intermodal Facility 179
Furman Aquatic Center 187
Ames/ISU Ice Arena 197
Water Treatment Plant 209
Solar Photovoltaic Array Assessment 219
Electric Vehicle Charging Assessment 227
B3 Benchmarking Facility Comparison 231
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Introduction4 5City of Ames Energy Audit City of Ames Energy AuditIntroduction
Project Team
Owner
City of Ames Pa Vang Goldbeck, Assistant City Manager
515 Clark Avenue Nolan Sagan, Sustainability Coordinator
Ames, Iowa 50010 Corey Mellies, Fleet Services Director
MEPT Engineer
Resource Consulting Engineers, LLC Corey Metzger, Principal, Project Manager & Mechanical Engineer
301 Alexander Avenue, Suite C James Deeds, Principal, Electrical Engineer
Ames, Iowa 50010 Scott Jasper, Mechanical Engineer
515.509.8905 Jenny Olson, Electrical Engineer
Architect
OPN Architects Joe Feldmann, Principal
100 Court Avenue, Suite 100 Rebecca Riss, Performance Director
Des Moines, Iowa 50309
515.309.0722
Energy Analyst
Willdan Joel Logan, Energy Analysis Manager
10858 Meredith Drive KC Reed, Energy Modeler
Urbandale, IA 50322 Aidan Vaughan, Energy Analyst
515.271.9923
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13 14
5
2
15 16
1
3
6 7 8 9
4
10
11
1 Homewood Golf Course Clubhouse
2 Furman Aquatic Center
3 Fire Station 1
4 Water Treatment Plant
5 CyRide Transit
6 Ames City Hall
7 Ames Public Library
8 Technical Services Complex
9 Electric Administration
10 Public Works
11 Electric Distribution
12 Ames Intermodal Facility
13 Ames Ice Arena
14 Parks and Recreation Admin Office
15 Airport Terminal
16 Fire Station 3
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Introduction6 7City of Ames Energy Audit City of Ames Energy AuditIntroduction
Executive Summary
large database of similar facilities, was completed for smaller or more typical facility types. The benchmarking
approach identifies estimated energy consumption by end use without detailed energy modeling. This allows for
useful information to be projected for smaller or more typical facility types that do not justify the more involved
and costly process of a detailed energy model. Finally, manual calculations were completed for facilities that might
be difficult to fully model and where appropriate benchmarking data was not available. This process focuses on
specific components or systems that represent significant energy consumption or potential savings, which is more
appropriate for facilities with unique or process-driven loads.
For the financial analysis, approximate expected costs were identified for each measure. The expected costs are
identified in the report as incremental costs in comparison to a baseline scenario cost. These costs were used
to determine simple payback for each strategy along with expected cost per unit of emissions saved (in kilogram
of carbon dioxide equivalent). These values can be used to compare strategies, both on a per-building basis and
across buildings to understand the potential savings in cost and emissions for each strategy.
Photovoltaic Array Assessment
The potential impacts of photovoltaics (PV, or solar panels) have been considered for five buildings, including:
• City Hall
• Water Treatment Plant
• Public Works and Fleet
• Electrical Distribution
• Animal Shelter
This information is presented separately from the individual building reports to provide all information related to
photovoltaics in one section of the report.
Electric Vehicle Charging Assessment
An assessment of the feasibility for Electric Vehicle (EV) charging was completed for 15 of the 16 buildings in
the energy audit, as well as the Animal Shelter. The Furman Aquatic Center was not considered a recommended
candidate for EV charging infrastructure since the facility is only used 3 months per year. The EV assessment is
based on current electrical system capacity to accommodate EV charging and considerations associated with
installing charging infrastructure.
Recommendations
The potential impact of identified strategies can be compared quickly based on the analysis providing simple
payback and cost per unit of emissions saved. While this provides an easy high-level comparison for strategies, it
is important to consider other factors, like ease of implementation, impact to facilities, and condition of existing
systems or components. Recommendations for implementation are included in the report, and for many systems or
components it is recommended that implementation occur at the end of the useful life of the existing equipment.
While this may delay direct energy and emissions savings, considerations related to embodied carbon in existing
equipment and new equipment is not accounted for in the analysis presented and would significantly change
some results and recommendations for equipment being replaced prior to the end of its useful life. There are
some strategies included that do not demonstrate a simple payback from a financial standpoint. Some of these
strategies don’t demonstrate a payback due to work associated with initial implementation compared to the
baseline option, but the strategies have been included as they may prove beneficial in meeting CAP goals.
The cumulative impact of implementing the recommended energy efficiency measures for the sixteen buildings
in the energy audit and installing PV on City Hall, Water Treatment Plant, Public Works and Fleet, and Electrical
Distribution is shown in the following graphs. Overall, these strategies have the potential to reduce net annual
energy use by 39%, reduce annual energy cost by 37% and reduce annual carbon emissions by 39%.
Executive Summary
Overview
The City of Ames has a demonstrated history of using resources responsibly and planning for sustainability and
efficiency. The Climate Action Plan (CAP) completed in 2023 sets targets for community greenhouse gas emission
reductions of 70% by 2030 and 94% by 2050. To achieve these targets, specific strategies are necessary to
reduce energy consumption, transition loads away from fossil fuels where appropriate, and deploy renewable
energy generation. The results of the Energy Audit Project should help inform decisions related to investments on
the path toward the CAP goals. While the Energy Audit Report does not include specific steps necessary to hit
these goals, it provides information related to expected energy and emissions reductions, along with comparisons
of expected cost-benefit for implementation of considered strategies. This information may be used to prioritize
strategies for implementation on the path toward emission reductions.
Building Energy Audit Process
The energy audit process completed as part of this project included multiple team members and consisted of
several steps. City of Ames personnel were critically important in data gathering and offering information related
to operational capabilities and issues for each facility. The Energy Audit Team (Resource Consulting Engineers,
LLC, OPN Architects, and Willdan) collected and analyzed information to provide the results included within this
document. Some city buildings were excluded from the study due to planned vacancies or minor energy use. These
include the Resource Recovery Plant, Fire Station #2, Cemetery Office, and Parks & Recreation Maintenance.
Energy Analysis Methodology
1. Detailed energy models were
completed for:
• Technical Services
Complex
• City Hall
• Ames Public Library
• Fire Station 1
2. Benchmarking analyses were
completed for:
• Fire Station 3
• Public Works and Fleet
• Electric Distribution
• Electric Administration
• Homewood Golf Course
Clubhouse
• Parks and Recreation
Administration
• Airport Terminal
3. Manual calculations were used
to analyze strategies for:
• CyRide Transit
• Ames Intermodal Facility
• Furman Aquatic Center
• Ames/ISU Ice Arena
• Water Treatment Plant
Initial Data Collection & Building Walkthroughs
Existing documentation for each facility was obtained by City of
Ames personnel and shared with the Energy Audit Team. This
documentation primarily consists of existing drawings. Energy
information was also shared by City of Ames personnel to inform the
energy analysis processes.
Site visits to observe existing conditions for each building were
completed by key City of Ames personnel along with members of
the Energy Audit Team (typically OPN Architects and Resource
Consulting Engineers).
Analysis of Recommended Energy Efficiency Measures
An analysis was completed for each facility based on the information
gathered from existing documentation, energy use data, and site
visits. A set of energy efficiency measures (EEMs) was developed
for each facility based on apparent opportunities to reduce energy
consumption. With these EEMs in mind, an analysis process was
completed for each building.
To both be efficient with City resources and to provide an adequate
level of analysis to properly inform the process, different approaches
were used for different facilities, as noted to the right. A detailed
energy model was generated for larger or more complex buildings
to allow for more customized results. The detailed energy modeling
process involves developing custom model components and
calibrating the model to available building energy consumption data
to identify expected energy consumption by end use (each building
system or component). A benchmarking analysis, informed by a
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Introduction8 9City of Ames Energy Audit City of Ames Energy AuditIntroduction
Executive Summary
Cumulative Annual Net Energy Use for Energy Audit Buildings
Cumulative Annual Energy Cost for Energy Audit Buildings
Cumulative Annual Carbon Emissions for Energy Audit Buildings
26%39%
16%37%
24%39%
Executive Summary
The total potential savings for implementing the proposed EEMs across all buildings is shown in the table below.
Total Potential Savings for EEM Implementation Across All Buildings
Building Potential Annual Savings Notes
Electric
Consumption
(kWh)
Natural Gas
(therms)
Energy Cost
($)
Emissions
(kgCO2e/yr)
Technical Services Complex 204,178 5,721 $13,995 120,129 EEMs 1A, 2-6, 7A & 8
City Hall 826,418 5,534 $86,568 461,360 EEMs 1A, 2-4 & 5A
Library -116,218 11,543 $(2,047)44,261 EEMs 1, 2 & 3A
Fire Station 1 -17,995 3,093 $812 18,699 EEMs 1B, 2, 3A & 4
Fire Station 3 -16,321 4,154 $1,902 29,195 EEMs 1A, 1B, 2B, 3A & 4
Public Works and Fleet -96,266 18,156 $650 131,008 EEMs 1-4
Electric Distribution 136,068 0 $14,079 70,783 EEMs 1-3, 4A & 5
Electric Administration 11,862 0 $1,227 6,171 EEMs 1-3 & 4A
Homewood Golf Course Clubhouse 1,313 297 $393 3,565 EEMs 1-3
Parks and Recreation Administration -11,019 2,725 $1,216 20,706 EEMs 1B & 2-7
Airport Terminal -8,064 1,774 $699 13,013 EEMs 1-3
CyRide Transit 17,682 7,862 $8,627 88,262 EEMs 1 & 2
Ames Intermodal Facility 0 0 0 0 -
Furman Aquatic Center -20,932 7,898 $4,662 65,738 EEMs 1 & 2
Ames/ISU Ice Arena 10,302 3,006 $3,665 34,523 EEMs 1 & 2
Water Treatment Plant 100,858 0 $10,436 52,466 EEM 1
Total Across All Facilities 1,021,866 71,763 $146,884.00 1,159,879
1 Includes natural gas and waste oil savings, in therms.
How to Use this Study
This report includes a section for each building energy audit, consisting of the following subsections:
• Facility Description: provides general building information along with system descriptions and photos.
• Notable Conditions Observed: includes the date of the site visit, key observations by system, and additional
photos.
• Utility Bill Analysis: provides historical data on energy consumption by source (electricity or natural gas) along
with associated costs and approximate equivalent carbon emissions.
• Benchmarking: where applicable for the building type, provides a high-level comparison of how the facility
performs compared to others in the dataset. (It is noted for some buildings that this comparison may
not be representative of high performance, as some operational deficiencies can lead to reduced energy
consumption.)
• Energy Analysis: describes the type of energy analysis (e.g., energy model, benchmarking, or manual
calculations), as well the building's energy end use characterization, where applicable.
• Energy Efficiency Measures (EEMs): describes each proposed EEM, along with information on the existing
condition and recommendations for implementation. Also includes tables describing incremental cost and
estimated savings for each EEM. The information included in these tables is for individual measures only
and does not account for combinations of measures. For select buildings, this section also includes graphs
showing combinations of strategies to demonstrate the results if multiple measures were incorporated
together.
• Appendix: for buildings with detailed energy modeling, an Appendix is included listing energy analysis inputs for
the facility.
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11City of Ames Energy AuditIntroduction10City of Ames Energy Audit
Executive Summary
If looking only at one building, it is recommended that all sections be reviewed to get a full understanding of existing
conditions, current energy and emissions performance, possible EEMs, and associated considerations. This
includes the review of implementing multiple EEMs for most facilities.
When looking at all or multiple buildings, it may be most efficient to look at the Estimated Costs for Individual
EEMs and Estimated Savings for Individual EEMs tables in the Energy Efficiency Measures section of the report
for each building. These tables provide an understanding of approximate incremental costs for implementation of
the strategies and provide common data points through which measures for different buildings may be compared.
Specifically, the incremental costs per carbon dioxide equivalent emissions column in the Estimated Savings for
Individual EEMs table provides an approximation of the return on investment for reducing emissions, with lower
costs in this column representing a better return on investment.
Information in the Solar Photovoltaic Array Assessment and Electric Vehicle Charging Assessment sections
provides a more direct means for comparing the feasibility of implementing either of these strategies for each
building. These strategies should be considered along with other strategies being considered in more detail for
each building prior to implementation to ensure expected strategies are compatible and do not result in unintended
consequences.
Energy Audit Assumptions
The information and analyses presented in this report are based on building walk-through observations, information
from City staff, available drawings, and standard design practices based on building vintage and program type.
Utility Rates
The energy rates used in the analyses are noted below:
Energy Source Utility Rate Source
Electric $0.103/kWh City of Ames Energy Star Portfolio Manager average rate
Natural Gas $0.8645/Therm City of Ames Energy Star Portfolio Manager average rate
Carbon Emissions Rates
The carbon emissions rates used in the analyses are noted below:
Energy Source Carbon Emissions Intensity Factor Source
Electric 0.5202 mt CO2e/MWh Ames Municipal Electric Utility
Natural Gas 20 lb CO2e/Therm Nationwide value
Waste Fuel 892 lbCO2e/MWh ICC Green Construction Code
Estimated Costs
Base costs have been identified for each energy efficiency measured based on high-level analysis of the strategy.
Incremental costs are premiums compared to the base costs, and are presented with a range of low to high
expected incremental costs. Available utility rebates have been identified where applicable and are factored into
the incremental costs. Available tax credits are not factored into the financial analysis, but have been identified for
applicable systems. Due to the nature of the project, the base costs do not represent detailed or exhaustive cost
estimates, and more consideration is likely necessary to confirm costs for larger or more complex projects.
Baseline and incremental costs provided in this report and used in the analyses are estimated based on 2025 cost
information available during the energy audit exercise. Impacts of inflation are not included.
Building Energy Audits
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13City of Ames Energy Audit
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Technical Services Complex
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Technical Services Complex14 15City of Ames Energy Audit City of Ames Energy AuditTechnical Services Complex
Facility Description
Building Contact Information
Building Name Technical Services Complex
Address 300 E 5th St #2
Ames, IA 50010
Building Owner City of Ames
Key Contact Jake Sisson, Water Meter Supervisor
Building Characteristics
General
Year of original construction: 1993
Building Climate Zone: 5A
Gross floor area: 9,450 sq.ft.
Total conditioned area: 9,450 sq.ft.
Total number of floors: 3, plus mechanical mezzanine
Conditioned floors above grade: 2, plus mechanical mezzanine
Conditioned floors below grade: 1
Use Type
Primary building use type: Office
Secondary building use type: Lab
Major Renovations
2014 Replaced ballasted EPDM roof with a ballasted rubber roof.
Operations
Typical weekly occupancy: Monday through Friday, 7:30 a.m to 4:30 p.m.
Typical annual occupancy: 52 weeks/year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
The typical composition of the above-grade exterior wall is 4” face brick,
2” rigid insulation, 8” concrete masonry unit, 6 mil poly vapor barrier, and
1/2” gypsum board. Spandrel panels appear to be uninsulated. The below-
grade exterior walls are concrete with a waterproofing membrane and a
2” insulated drainage panel. The first floor slab-on-grade includes sand, a
poly vapor barrier and granular fill below the concrete slab. The basement
floor includes a 2” insulated drainage panel, a waterproofing membrane, and
granular fill below the concrete slab.
The window to wall ratio is approximately 16% and the windows are original
to the building. The windows are aluminum framed with double-pane tinted
glazing. Windows into administrative office areas and the lab meter room
have an operable component, while the remaining windows are fixed. Main
building entrances include glazed entry doors that enter into vestibules, and
the garage is equipped with insulated sectional overhead garage doors.
There are two primary roof systems for the building: a flat ballasted
membrane roof and a pitched standing seam copper roof. The flat roof
system includes 4” of rigid insulation over the 12” precast concrete core
slab. The majority of the pitched roof includes 6” of batt insulation in
between ceiling joists, with the exception of the pitched roof over the
mechanical mezzanine, which includes 6” of batt insulation in between the
rafters of the light gauge metal truss.
Lighting System
Building lighting systems typically consist of fluorescent fixtures. Storage
and maintenance areas appear to utilize T12 fluorescent lamps, while other
areas appear to use more efficient lamps (though less efficient than LED).
No automatic lighting controls, dimming capabilities, or daylighting control
were observed.
HVAC Systems
The building HVAC system generally consists of a central plant producing
heating and chilled water, paired with two (2) constant-volume multi-zone
air handling units. Exhaust fans serve dedicated loads for both general
and process exhaust. With the exception of the two (2) boilers, equipment
typically appears to be original to the building.
The air-cooled chiller includes a remote-mounted condenser at grade, with
the compressor, heat exchanger, and other components located in the lower-
level mechanical room. The chilled water pump is also located in this space.
The chiller appears to be original to the building.
West Elevation
East Elevation
Roof
T12 Fluorescent Lamps (34W)
Existing Boilers
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Technical Services Complex16 17City of Ames Energy Audit City of Ames Energy AuditTechnical Services Complex
Facility Description
Two (2) heating hot water boilers serve the building. One boiler is a high-
efficiency condensing type boiler, while the other is a standard efficiency
boiler. The boilers serve the two air handling units along with a domestic hot
water heat exchanger and storage tank. Perimeter heat in six (6) zones is
also served by hot water from the boilers.
Air handling unit AHU-1 serves seven zones, each equipped with a dedicated
multi-zone damper assembly (mixing air from the hot and cold decks of the
AHU). AHU-1 serves all spaces on the first floor of the building (four zones),
apart from the garage area (Room 112). AHU-1 also serves three zones on
the second floor of the building. All but one of the zones served by AHU-1
also have perimeter hot water heating.
Air handling unit AHU-2 serves three (3) zones, each equipped with a
dedicated multi-zone damper assembly. AHU-1 serves the laboratory
spaces on the second floor of the building. None of these zones are
equipped with perimeter heating.
A small general exhaust fan serves restrooms in the building. Dedicated
exhaust fans serve fume hoods and other dedicated/process exhaust in the
laboratory areas of the building.
Plumbing Systems
Building domestic hot water is provided by a heat exchanger and storage
tank, heated by the building heating hot water loop. Compressed air and
vacuum for the laboratory space are provided by equipment in the building
as well.
Existing Air-Cooled Chiller
Existing Air Handling Unit
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on March 11, 2025.
Observations
Building Envelope
• Multiple windows had a broken seal.
• Multiple windows had a broken lever, impacting operability of the window.
• Garage ceiling is not insulated, but adding insulation would be difficult
with current piping configuration. Garage is heated to prevent freezing of
exposed pipes.
Lighting Systems
• Lighting is typically fluorescent, including some areas with T12
lamps (inefficient by modern standards) - newer LED technology is
more efficient, may provide better lighting quality, and requires less
maintenance to operate.
• There are no automatic lighting controls, dimming, or daylighting controls
– automatic controls (occupancy/vacancy) and daylighting controls are
required by modern energy codes.
HVAC Systems
• System components are mostly original and have exceeded their
expected useful lives.
• Multi-zone air handling units are no longer allowed by code due to their
inherently high energy consumption.
• There is limited redundancy for key building components (heating water
being an exception).
• There is significant exhaust from the lab area – energy recovery would be
ideal to incorporate where feasible.
Plumbing Systems
• Source of heating coming from boilers likely prevents condensing boiler
from achieving target efficiency, as higher supply water temperature will
be necessary with heat exchanger to generate domestic hot water.
Window with broken seal
Window with broken lever
Garage with exposed piping
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Technical Services Complex18 19City of Ames Energy Audit City of Ames Energy AuditTechnical Services Complex
Monthly Electric Usage
The monthly electrical consumption profile shows a typical pattern of higher usage in the summer than in the
winter due to cooling loads.
Monthly Natural Gas Usage
The monthly natural gas consumption profile shows a typical pattern of higher usage in the winter than in the
summer due to natural gas serving the heating loads. Natural gas consumption remains high during the summer
due to water heating and process loads.
Overview
Metered energy data from January 2020 through November 2024 was collected during the audit and is
documented below. The building uses a significant amount of energy due to the type and age of the building
systems, significant process loads in the laboratory, and ventilation requirements. Due to the high energy use and
age of the building systems, the building is a high priority for retrofits to reduce energy consumption.
Natural gas makes up approximately 60% of the energy use, but only about one third of the energy cost of the
building. The energy related carbon emissions of the building are roughly split between natural gas and electricity.
Utility Bill Analysis
251.6
kBtu/ft2/yr
Energy Use
Annual Energy Use Intensity (EUI)
Based on measured energy use between
December 2023 and November 2024, the
building has an energy use intensity of 251.6
kBtu/sq.ft./yr. 63% of the building’s annual
energy use is attributed to natural gas, while
the remaining 37% of the building’s annual
energy use is attributed to electricity.
Monthly Natural Gas Use
Dec 2023-Nov2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Monthly Electric Use
Dec 2023-Nov 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Annual Energy Use Intensity
Dec 2023-Nov 2024
Electric
Natural Gas
Electric
12/23-11/24
Electric Baseline1/20-12/20
kW
h
Natural Gas
12/23-11/24
Natural Gas Baseline1/20-12/20
Th
e
r
m
s
Dec 2023 - Nov 2024
Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 20240
10,000
20,000
30,000
40,000
0
1,000
2,000
3,000
Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 2024
0
100
200
300
Energy Cost
Annual Energy Cost
Based on the measured energy use and utility bills between December 2023 and November 2024, the building’s
annual energy cost is $39,505. 33% of the building’s annual energy cost is attributed to natural gas, while the
remaining 67% of the building’s annual energy cost is attributed to electricity. The annual energy cost between
December 2023 and November 2024 was slightly less than annual energy costs in 2021 through 2023, when
annual energy costs exceeded $40,000.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use between January 2023 and December 2023, the building’s annual carbon
emissions is approximately 227 mt-CO2e/yr. About 42% of the building’s annual carbon emissions is attributed to
natural gas, and 58% is attributed to electricity.
Utility Bill Analysis
$39,505/yr
Annual Energy Cost Comparison
2021-2023
Annual Carbon Emissions
2023
Annual Energy Costs
Dec 2023-Nov 2024
Electric
Natural Gas
Electric
Natural Gas
Electric
Natural Gas
Me
t
r
i
c
T
o
n
s
C
O
2e
Co
s
t
2023
0
100
200
300
2021 2022 2023
0
$20,000
$40,000
$60,000
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Technical Services Complex20 21City of Ames Energy Audit City of Ames Energy AuditTechnical Services Complex
The building ranks in the 23rd percentile to 66 other peer laboratory buildings in the B3 Benchmarking tool (77%
of laboratory buildings have better performance). This indicates that the building is a good candidate for reducing
energy use through retrofits.
The B3 Benchmark Rating is an easy to understand 1 to 5 star-ranking system. For the energy benchmark, it is
based on the ratio of actual kBtu per square foot compared to the benchmark kBtu per square foot model. A rating
higher than 2 1/2 stars means the building is performing better than expected. A rating less than 2 1/2 stars
indicates greater potential for savings.
Benchmarking
B3 Benchmarking Comparison
2 8 14 20 26 32 38 45 51 57 63 69 75 82 88 94 100
Be
n
c
h
m
a
r
k
i
n
g
R
a
t
i
n
g
Peer Rating
0
1
3
2
4
5
Methodology
The energy use of the building and the energy efficiency measures were analyzed using a detailed energy model
and tuned to the actual overall energy consumption of the facility. The detailed energy model models the hourly
energy use of all components of the building over a year. The inputs to the energy model were obtained through
conversations with city staff, the facility walk through, and documents provided by the city staff. When information
was not available through these methods, building characteristics were assumed based on building vintage and
engineering judgment.
Energy Use Characterization
The following graph shows the modeled annual energy use of the existing building broken down by end use.
Heating energy is the dominant energy use, followed by process load in the laboratory.
Energy Analysis
Electricity Natural GasEUI(kBtu/sq.ft./yr)
kB
T
U
/
f
t
2
/
y
r
Existing
Energy Use Characterization by Energy End Use
0
50
100
150
200
250
300
Total 262.8
Process Loads 60.5
Interior Equipment 22.6
Interior Lighting 24.3
Domestic Hot Water 4.2
Pumps 3.4
Fans 19.9
Cooling 20.2
Heating 107.5
13
Technical Services Complex22 23City of Ames Energy Audit City of Ames Energy AuditTechnical Services Complex
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1A: HVAC System Retrofit with DOAS and FCUs
• Existing Condition: HVAC systems have exceeded expected useful life and have very high energy consumption –
additionally, current system configuration is antiquated and not recommended for continued use.
• Proposed Energy Efficiency Measure: Retrofit building HVAC system with new central plant including air-to-
water heat pump(s) to produce chilled or heating water, new piping, one new DOAS air handling unit to serve all
building spaces along with fan coil units (FCUs) to condition to each space, new perimeter heating equipment,
and new exhaust systems – consideration for energy recovery included where believed to be feasible.
• Recommendation for Implementation: To be implemented when determined to be feasible for full retrofit,
which will significantly impact building operations – if addition or other modifications are considered for the
building, different equipment configurations or applications should be considered.
EEM 1B: HVAC System Retrofit with VAV AHU and Terminal Units
• Existing Condition: HVAC systems have exceeded expected useful life and have very high energy consumption
– additionally, current system configuration is antiquated and not recommended for continued use.
• Proposed Energy Efficiency Measure: Retrofit building HVAC system with new central plant including air-to-
water heat pump(s) to produce chilled or heating water, new piping, new variable air volume (VAV) air handling
unit (AHU) to serve all building spaces along with terminal equipment to control airflow to each space, new
perimeter heating equipment, and new exhaust systems – consideration for energy recovery included where
believed to be feasible.
• Recommendation for Implementation: To be implemented when determined to be feasible for full retrofit,
which will significantly impact building operations – if addition or other modifications are considered for the
building, different equipment configurations or applications should be considered.
EEM 2: Lighting System Retrofit to LED
• Existing Condition: Fluorescent lighting throughout most of building and only manual control.
• Proposed Energy Efficiency Measure: Replace all lighting with LED fixtures (unless needed for specific
process or operations) and controls, including occupancy/vacancy, dimming, and daylighting.
• Recommendation for Implementation: To be implemented when determined to be feasible for full retrofit,
which will significantly impact building operations. It should be noted that the simple payback presented in the
Estimated Savings for EEMs table is calculated based on energy cost savings and first cost only, and does not
account for maintenance costs associated with replacing lamps in existing fluorescent fixtures. Accounting for
these maintenance costs would improve the payback associated with this strategy, but to maintain consistency
across the simple payback calculations presented in the Estimated Savings for EEMs table, the life cycle cost
savings associated with lamp replacement were not included.
EEM 3: Dimming Daylighting
• Existing Condition: Building does not have any automatic lighting controls.
• Proposed Energy Efficiency Measure: Add daylighting controls to adjust lighting levels (dim lighting) based on
available ambient lighting levels.
• Recommendation for Implementation: Likely not feasible with existing fluorescent fixtures without replacing
the existing ballasts, which is not recommended.
Energy Efficiency Measures
EEM 4: Lighting Occupancy and Vacancy Sensor Controls
• Existing Condition: Building does not have any automatic lighting controls.
• Proposed Energy Efficiency Measure: Add occupancy- or vacancy-based lighting controls to occupied spaces
wherever appropriate or required by code.
• Recommendation for Implementation: Recommend implementation at time of other improvements/retrofit
work to prevent re-work and impact to building operations.
EEM 5: Heat Pump Water Heater
• Existing Condition: Hot water generated at heat exchanger served by boiler system.
• Proposed Energy Efficiency Measure: Standalone water heater – recommend considering hybrid heat pump
water heater if capacity meets building demands.
• Recommendation for Implementation: Can replace existing water heater/storage tank and will need electrical
circuit and review of impact on adjacent space (lower-level mechanical room) - may be implemented prior to
other changes if determined to be appropriate – don’t recommend doing so unless needed for other reasons (if
water heater is in need of replacement).
EEM 6: Night Temperature Setback
• Existing Condition: No setback.
• Proposed Energy Efficiency Measure: Add setback controls to reset temperature setpoints for unoccupied
hours.
• Recommendation for Implementation: To be included in EEM 1A or 1B – consider implementation prior if
existing systems will continue to operate for longer period.
EEM 7A & 7B: Window Replacement
• Existing Condition: The existing windows are original to the 1993 building and are approaching their useful
end of life. The aluminum framed double-glazed windows are experiencing issues with broken window seals and
operability.
• Proposed Energy Efficiency Measure: Replace windows with a high-performing thermally-broken window
assembly that is better than current energy code minimums. EEM 7A evaluates the impact of a window
assembly with a U-factor of 0.29 and a Solar Heat Gain Coefficient (SHGC) of 0.32, while EEM 7B evaluates
the impact of a window assembly with a U-factor of 0.36 and a SHGC of 0.38.
• Recommendation for Implementation: Recommend implementing as part of a full building retrofit, since
replacing windows will significantly impact building operations. EEM 7A is recommended as a higher-
performance option, provided that the cost difference between the two options is minimal.
EEM 8: Roof Insulation Increase
• Existing Condition: The existing sloped roofs have an approximate R-value of R-14, below the current energy
code minimum requirements for thermal performance.
• Proposed Energy Efficiency Measure: In areas with sloped roofs and batt insulation in between the ceiling
joists, add additional insulation to increase the overall thermal performance to R-30.
• Recommendation for Implementation: Recommend implementation at time of other improvements/retrofit
work to reduce impact to building operations.
Energy Efficiency Measures
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Technical Services Complex24 25City of Ames Energy Audit City of Ames Energy AuditTechnical Services Complex
Estimated Costs for Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate EEM Incremental Cost
Low High
1A HVAC System Retrofit with DOAS and
FCUs
Direct replacement of existing system
with modern controls/components
$756,000 $0 $189,000 $330,750
1B HVAC System Retrofit with VAV AHU and
Terminal Units
Direct replacement of existing system
with modern controls/components
$756,000 $0 $94,500 $283,500
2 Lighting System Retrofit to LED Existing lighting to remain $0 $0 $28,173 $47,250
3 Dimming Daylighting No changes to lighting controls $0 $0 $1,999 $9,450
4 Lighting Occupancy and Vacancy Sensor
Controls
No changes to lighting controls $0 $0 $5,704 $18,900
5 Heat Pump Water Heater Replacement with standard efficiency
natural gas-fired water heater
$3,000 $400 $5,350 $6,100
6 Night Temperature Setback No control changes for current system $0 $0 $2,812 $5,000
7A Window Replacement:
U-factor 0.29, SHGC 0.32
Replacement with energy code-compliant
window
$57,458 $- $5,746 $24,707
7B Window Replacement:
U-factor 0.36, SHGC 0.38
Replacement with energy-code compliant
window
$57,458 $- $- $11,492
8 Roof Insulation Increase No changes to roof insulation $0 $- $4,056 $6,995
Energy Efficiency Measures
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved1
($/kgCO2e)
Average
Simple
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms Energy
Cost
CO2
Emissions
(kgCO2e)
1A HVAC System Retrofit with
DOAS and FCUs
HVAC
System
(22,682) 10,532 $6,758 83,747 $0.11 -
$0.20
N/A Implement as soon as
feasible (existing sys-
tems have exceeded
useful life) depending
on building needs
1B HVAC System Retrofit with
VAV AHU and Terminal Units
HVAC
System
(22,016) 10,532 $6,827 84,094 $0.06 -
$0.17
N/A
2 Lighting System Retrofit to
LED
Lighting 21 53,723 (765) $4,902 21,010 $0.07 -
$0.11
7.7 Implement as soon as
feasible (existing sys-
tems have exceeded
useful life) depending
on building needs
3 Dimming Daylighting Lighting 12 19,380 (390) $1,676 6,547 $0.02 -
$0.07
3.4
4 Lighting Occupancy and
Vacancy Sensor Controls
Lighting 4 17,791 (291) $1,592 6,615 $0.04 -
$0.14
7.7
5 Heat Pump Water Heater Plumbing
System
(2) (2,457) 399 $91 2,342 $0.23 -
$0.26
N/A Implement at end of
system life
6 Night Temperature Setback HVAC System (0) 3,231 265 $563 4,083 $0.07 - $0.12 6.9 Implement as soon as feasible
7A Window Replacement:
U-factor 0.29, SHGC 0.32
Building
Envelope
2 1,057 581 $612 5,821 $0.03 -
$0.14
24.9 Implement as soon as
feasible (existing sys-
tems have exceeded
useful life) depending
on building needs
7B Window Replacement:
U-factor 0.36, SHGC 0.38
Building
Envelope
1 351 494 $462 4,668 $0 - $0.08 12.4
8 Roof Insulation Increase Building
Envelope
1 278 133 $145 1,347 $0.10 -
$0.17
N/A Implement with other
major improvements
1 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to
have a life of 10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either
15 years for smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-
fired equipment.
Estimated Savings For Bundled EEMs
Estimated energy savings from implementing all recommended measures are shown in the following charts. The first
chart shows the savings in annual EUI, the second chart shows the savings in annual energy cost, and the third chart
shows the savings in annual carbon emissions. The columns are described as follows:
• Non-Mechanical Strategies: Implement EEMs 2-5, 7A, and 8 to improve lighting, building envelope and domestic
hot water systems.
• Mechanical Strategy 1A: Implement EEM 1A by replacing the existing mechanical system with a system
comprised of fan coils and a dedicated outdoor air system.
• Mechanical Strategy 1A Plus Non-Mechanical Strategies: Implement EEMs 1A, 2-6, 7A, and 8 to improve
mechanical, lighting, building envelope and domestic hot water systems.
• Mechanical Strategy 1B: Implement EEM 1B by replacing the existing mechanical system with a multizone
variable air volume system.
• Mechanical Strategy 1B Plus Non-Mechanical Strategies: Implement EEMs 1B, 2-6, 7A, and 8 to improve
mechanical, lighting, building envelope and domestic hot water systems.
Energy Efficiency Measures
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Technical Services Complex26 27City of Ames Energy Audit City of Ames Energy AuditTechnical Services Complex
Energy Efficiency Measures
Predicted Annual EUI Savings
kB
T
U
/
f
t
2/y
r
Predicted Annual Energy Cost Savings
Predicted Annual Carbon Emissions Savings
kg
C
O
2e
HVAC Controls
Operations
Program Type & Building Geometry
Appendix: Energy Analysis Inputs
Energy analysis inputs and assumptions are described below. This information is based on building walk-through
observations, information from City staff, available drawings, and standard design practices based on building
vintage and program type.
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Technical Services Complex28 29City of Ames Energy Audit City of Ames Energy AuditTechnical Services Complex
Appendix: Energy Analysis Inputs
Ventilation Requirements
Lighting
Service Hot Water & Other Loads
Appendix: Energy Analysis Inputs
Fenestration
Envelope
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31City of Ames Energy Audit
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City Hall
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City Hall32 33City of Ames Energy Audit City of Ames Energy AuditCity Hall
Facility Description
Building Contact Information
Building Name City Hall
Address 515 Clark Avenue
Ames, IA 50010
Building Owner City of Ames
Key Contact Corey Mellies, Fleet Services Director
Building Characteristics
General
Year of original construction: 1939
Building Climate Zone: 5A
Gross floor area: 90,000 sq.ft.
Total conditioned area: 90,000 sq.ft.
Total number of floors: 3
Conditioned floors above grade: 2
Conditioned floors below grade: 1
Use Type
Primary building use type: Office
Secondary building use types: Theater/Auditorium & Gymnasium
Major Renovations
1988 Major renovation and addition to convert the building from a junior high
school to City Hall
2014 Major renovation, Phase 2
2015 Roof renovation
2025 Auditorium HVAC improvements
Operations
Typical weekly occupancy: Monday through Friday, 8:00 am until 5:00 pm
Typical annual occupancy: 52 weeks/year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
The building features brick masonry walls original to the 1938 building.
As part of the 1988 renovation, new ⁵/₈” gypsum board was added with
2” of rigid in-between 2-1/₂” metal studs spaced 16” on center. The 1988
addition also introduced areas of spandrel panel, consisting of a double-pane
insulated glazing unit, 2” of rigid in-between 2-1/₂” metal studs spaced 16”
on center, and ⁵/₈” gypsum board. The 1988 addition for the MEP room used
uninsulated walls with 4” face brick and 8” concrete masonry units. Below-
grade walls are concrete foundation walls, with 1-5/8” metal studs with rigid
insulation and 5/8” gypsum board for office areas.
The window to wall ratio is approximately 20%. The majority of the windows
were installed in 1988 and feature aluminum frame, tinted double pane
glazing assemblies. Some windows on the basement level were replaced
as part of the 2014 renovation. The majority of the windows in office
areas feature an operable component for natural ventilation. Main building
entrances include wood doors that enter into vestibules, and the garage is
equipped with an insulated sectional overhead garage door.
The roof was renovated in 2015. As part of the renovation, a new black
EPDM roof membrane, gypsum cover board and polyiso insulation was
installed. Existing EPS insulation and fiberboard insulation was repaired
as needed and remained in place. The amount of insulation varies across
the roof and the roof assembly performance ranges from approximately
R-20 to R-35, with the majority of the roof assemblies achieving thermal
performance of R-30 to R-35.
Lighting System
Many fixtures have been upgraded to LED or retrofitted with LED lamps,
however lighting controls are typically manual throughout occupied building
areas.
HVAC Systems
The building HVAC system generally consists of a central plant providing
heat pump loop water to water-source heat pumps. There are two (2) air
handling units (or large blower coils) serving the gymnasium and new air
handling units are currently being installed to serve the auditorium. An
energy recovery ventilator and a dedicated outdoor air system rooftop unit
provide ventilation to the office portion of the building.
The central plant consists of two (2) closed-circuit cooling towers (fluid
coolers), electric steam boilers, a steam-to-water heat exchanger, pumps,
valves, controls, and accessories. The auditorium HVAC improvements
project currently underway will add air-to-water heat pumps to provide dual-
East Elevation
Roof
Corridor Lighting
Gymnasium Lighting
Historic Lighting
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City Hall34 35City of Ames Energy Audit City of Ames Energy AuditCity Hall
Facility Description
temperature water (chilled water or heating water) to new auditorium air
handling units, and will also provide heat to the heat pump loop during the
heating season (serving as the first stage of heat with the electric steam
boilers serving as the second stage of heat). A new water-to-water heat
pump will provide reheat water to the auditorium air handling units.
The packaged water-source heat pumps throughout the building either pull
or reject heat from/to the heat pump loop. The single dedicated outdoor air
system rooftop unit is equipped with natural gas-fired heating and an air-
cooled direct-expansion (DX) cooling system.
The air handling units serving the gymnasium are served by DX condensing
units located at grade on the west side of the building for cooling, and are
served by steam for heating. The units are not connected to a central
control system, but do appear to have economizer capabilities.
The new auditorium air handling units have dual-temperature water coils
for primary heating or cooling, along with reheat coils to prevent subcooling
during cooling mode operation. The larger unit serving most of the space
provides all normal ventilation and is equipped with an energy recovery wheel
and an electric heating coil in the return section of the unit.
Some pneumatic controls remain and the central plant control system is
antiquated. These components will be replaced as part of the auditorium
HVAC improvements project, with new direct digital controls serving the
entire central plant and connecting this system to the existing controls
for heat pumps throughout the building. This project does not bring the
gymnasium air handling units onto the common control system for the
remainder of the building.
Plumbing Systems
Building domestic hot water is provided by a standard efficiency natural
gas-fired domestic hot water heater (tank-type). The water heater is newly
installed as part of the Auditorium HVAC System Improvements project.
Electric Boiler
Fluid Coolers and Electrical Gear
Gymnasium AHU
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on February 27, 2025.
Observations
Building Envelope
• Majority of exterior doors have insufficient weatherstripping and
noticeable gaps that contribute to unwanted infiltration. Recommend
replacing with higher-performance, better-fitted doors as soon as
feasible. Insulated non-wood doors with glazed lites are preferred
if allowed by historical criteria. In the interim, recommend fixing the
weather stripping to reduce infiltration.
• Building staff noted issues of condensation and thermal discomfort
with existing windows. Condensation was not observed the day of the
walkthrough, but thermal bridging issues were observed.
• Portion of basement wall appeared to missing insulation, as indicated
by dark blue surface in the corresponding thermal image. Recommend
insulating this area during the next opportunity for renovation of this
room.
Lighting Systems
• Manual lighting controls provide significant opportunity for energy
savings.
HVAC Systems
• Heat pump loop piping is not insulated – this will limit allowable operating
temperatures to prevent condensation during the cooling season,
particularly if chilled water or ground-source loop water are introduced
into this system.
• The building does not have ventilation complying with modern code
requirements.
• Building controls for most areas (serving water-source heat pumps and
associated components) are nearing the end of their expected useful
lives.
• Building water-source heat pump units are nearing the end of their
expected useful lives (over ten years out of a fifteen to twenty year
useful life).
Plumbing Systems
• Standard efficiency natural gas-fired water heater is new as part of
Auditorium HVAC Project.
Entry door with visible gaps
Uninsulated wall in basement office
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City Hall36 37City of Ames Energy Audit City of Ames Energy AuditCity Hall
Monthly Electric Usage
The monthly electrical consumption shows a pattern of higher usage in the winter due to electricity being the
primary heating energy source.
Monthly Natural Gas Usage
The monthly natural gas consumption shows a pattern of higher usage in the winter due to heating loads. The
summer natural gas consumption is attributed to domestic water heating.
Overview
Metered energy data from January 2020 through November 2024 was collected during the audit and is
documented below. The energy use of the City Hall is dominated by electricity due to electricity being the primary
heating energy source. The age and type of the building’s mechanical systems make it a good candidate for
improving energy efficiency.
Utility Bill Analysis
67.2
kBtu/ft2/yr
Energy Use
Annual Energy Use Intensity (EUI)
Based on measured energy use between
December 2023 and November 2024 the
building has an energy use intensity of 67.2
kBtu/sq.ft./yr. 91% of the building’s annual
energy use is attributed to electricity, while
the remaining 9% of the building’s annual
energy use is attributed to natural gas.
Monthly Natural Gas Use
Dec 2023-Nov2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Monthly Electric Use
Dec 2023-Nov 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Annual Energy Use Intensity
Dec 2023-Nov 2024
Electric
Natural Gas
Electric
12/23-11/24
Electric Baseline1/20-12/20
kW
h
Natural Gas12/23-11/24
Natural Gas Baseline1/20-12/20
Th
e
r
m
s
Dec 2023 - Nov 2024
Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 20240
50,000
100,000
150,000
200,000
0
1,000
2,000
3,000
Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 2024
0
50
100
Energy Cost
Annual Energy Cost
Based on the measured energy use and utility bills between December 2023 and November 2024, the building’s
annual energy cost is $170,975. 97% of the building’s annual energy cost is attributed to electricity, while the
remaining 3% of the building’s annual energy cost is attributed to natural gas. The annual energy cost in 2022 was
higher than in 2021 or 2023, when total energy costs exceeded $195,000.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use between January 2023 and December 2023, the building’s annual carbon
emissions is 902 mt CO2e/yr. About 96% of the building’s annual CO2e emissions is attributed to electricity
and about 4% is attributed to natural gas.
Utility Bill Analysis
$170,975/yr
Annual Energy Cost Comparison
2021-2023
Annual Carbon Emissions
2023
Annual Energy Costs
Dec 2023-Nov 2024
Electric
Natural Gas
Electric
Natural Gas
Electric
Natural Gas
Me
t
r
i
c
T
o
n
s
C
O
2e
Co
s
t
2023
0
500
1,000
2021 2022 2023
0
$50,000
$100,000
$200,000
$150,000
21
City Hall38 39City of Ames Energy Audit City of Ames Energy AuditCity Hall
The building ranks in the 52 percentile to 3,840 other peer office buildings in the B3 Benchmarking tool (48% of
office buildings have better performance). This indicates that the building is a good candidate for reducing energy
use through retrofits.
The B3 Benchmark Rating is an easy to understand 1 to 5 star-ranking system. For the energy benchmark, it is
based on the ratio of actual kBtu per square foot compared to the benchmark kBtu per square foot model. A rating
higher than 2 1/2 stars means the building is performing better than expected. A rating less than 2 1/2 stars
indicates greater potential for savings.
Benchmarking
B3 Benchmarking Comparison
0 4 12 20 24 32 40 44 52 56 64 68 76 80 88 92 100
Be
n
c
h
m
a
r
k
i
n
g
R
a
t
i
n
g
Peer Rating
0
1
3
2
4
5
8 16 28 36 48 60 72 84 96
Methodology
The energy use of the building and the energy efficiency measures were analyzed using a detailed energy model
and tuned to the actual overall energy consumption of the facility. The detailed energy model models the hourly
energy use of all components of the building over a year. The inputs to the energy model were obtained through
conversations with city staff, the facility walk through, and documents provided by the city staff. When information
was not available through these methods, building characteristics were assumed based on building vintage and
engineering judgment.
Energy Use Characterization
The following graph shows the modeled energy use of the building broken down by end use. Heating energy is the
dominant energy use, followed by cooling load. Reducing heating and cooling loads and installing more efficient
HVAC systems show the largest opportunity for saving energy.
Energy Analysis
Electricity Natural
Gas
EUI
(kBtu/sq.ft./yr)
kB
T
U
/
f
t
2
/
y
r
Existing
Energy Use Characterization by Energy End Use
0
10
20
40
50
60
70
Total 67.4
Interior Equipment 10.1
Interior Lighting 8.1
Domestic Hot Water 1.6
Pumps 1.3
Fans 9.7
Heat Rejection 0.8
Cooling 10.5
Heating 25.2
30
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City Hall40 41City of Ames Energy Audit City of Ames Energy AuditCity Hall
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1A - Mechanical System Replacement with Ground-Source Heat Pumps
• Existing Condition: Water-source heat pump system, using electric boilers and closed-circuit cooling towers to
serve water-source heat pumps (will soon incorporate air-to-water heat pumps to supplement heating).
• Proposed Energy Efficiency Measure: Provide ground-coupled heat exchanger to replace or supplement
boilers and cooling towers for distributed water-source heat pumps in building.
• Recommendation for Implementation: Consider implementation when water-source heat pumps are scheduled
for replacement (requires additional review to determine best course of action). At time of implementation,
consider the potential federal government incentive for ground-coupled (geothermal) systems, which is
currently a 30% incentive under Section 48 of the tax code. This incentive is available to public entities in the
form of direct payment and is scheduled for phase out between 2033-2035.
EEM 1B - Mechanical System Replacement with Air-to-Water Heat Pump
• Existing Condition: Water-source heat pump system, using electric boilers and closed-circuit cooling towers to
serve water-source heat pumps (will soon incorporate air-to-water heat pumps to supplement heating).
• Proposed Energy Efficiency Measure: Provide additional air-to-water heat pump capacity to provide all heating
for heat pump loop and to supplement cooling for loop if needed (this would be in place of a ground-coupled
system).
• Recommendation for Implementation: Consider implementation when water-source heat pumps are scheduled
for replacement (requires additional review to determine best course of action).
EEM 2 - Dimming Daylighting
• Existing Condition: Building does not have any automatic lighting controls.
• Proposed Energy Efficiency Measure: Add daylighting controls to adjust lighting levels (dim lighting) based on
available ambient lighting levels.
• Recommendation for Implementation: Consider implementation schedule to limit impact to building, but will
have benefit as soon as it is implemented (may depend on implemented technology for lighting control).
EEM 3 - Lighting Occupancy and Vacancy Sensor Controls
• Existing Condition: Building does not have any automatic lighting controls.
• Proposed Energy Efficiency Measure: Add occupancy- or vacancy-based lighting controls to occupied spaces
wherever appropriate or required by code.
• Recommendation for Implementation: Consider implementation schedule to limit impact to building, but will
have benefit as soon as it is implemented (may depend on implemented technology for lighting control).
EEM 4 - Heat Pump Water Heater
• Existing Condition: Hot water generated by tank-type standard efficiency water heater.
• Proposed Energy Efficiency Measure: Heat pump water heater (expected to meet building demands).
• Recommendation for Implementation: When current water heater replacement is necessary, utilize heat pump
water heater as appropriate (may work well in current space due to higher summer temperatures in area – need
to verify there won’t be issues during heating season with reducing space temperature).
Energy Efficiency Measures
EEM 5A & 5B - Window Replacement
• Existing Condition: The majority of the existing windows were installed as part of the 1988 renovation and are
approaching their useful end of life. The aluminum framed double-glazed windows are experiencing issues with
condensation and thermal comfort.
• Proposed Energy Efficiency Measure: Replace 1988 windows with a high-performing thermally-broken
window assembly that is better than current energy code minimums. EEM 5A evaluates the impact of a window
assembly with a U-factor of 0.29 and a Solar Heat Gain Coefficient (SHGC) of 0.32, while EEM 5B evaluates
the impact of a window assembly with a U-factor of 0.36 and a SHGC of 0.38. EEM 5A is recommended as a
higher-performance option, provided that the cost difference between the two options is minimal.
• Recommendation for Implementation: Recommend implementing at end of window life and preferably as
part of a larger building retrofit, since replacing windows will significantly impact building operations. The
performance of EEM 5B is typical of a high-performing double-pane window, while the performance of EEM 5A
is achievable with either a higher-performing double-pane window or a triple-pane window.
Estimated Costs for Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate EEM Incremental Cost
Low High
1A Mechanical System Replacement with Ground Source Heat Pumps
Direct system replacement addressing ventilation deficiencies $4,500,000 $84,000 $1,206,000 $1,656,000
1B Mechanical System
Replacement with Air to Water Heat Pump
Direct system replacement addressing
ventilation deficiencies
$4,500,000 $0 $450,000 $900,000
2 Dimming Daylighting No changes to lighting controls $0 $0 $67,500 $90,000
3 Lighting Occupancy and Vacancy Sensor Controls No changes to lighting controls $0 $0 $135,000 $180,000
4 Heat Pump Water Heater Replacement with standard efficiency
natural gas-fired water heater
$3,000 $400 $3,100 $3,850
5A Window Replacement:
U-factor 0.29, SHGC 0.32
Replacement with energy code-compliant
window
$417,448 $0 $37,950 $163,184
5B Window Replacement: U-factor 0.36, SHGC 0.38 Replacement with energy code-compliant window $417,448 $0 $0 $75,890
Energy Efficiency Measures
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City Hall42 43City of Ames Energy Audit City of Ames Energy AuditCity Hall
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved1
($/kgCO2e)
Average
Simple
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms Energy
Cost
CO2
Emissions
(kgCO2e)
1A Mechanical System
Replacement with Ground
Source Heat Pumps
HVAC
System
0 665,695 5,534 $73,666 396,499 $0.203 -
$0.278
19.4 Implement at end of
system life (approxi-
mately 5-7 years)
1B Mechanical System
Replacement with Air to
Water Heat Pump
HVAC
System
0 505,060 5,534 $57,045 312,937 $0.096 -
$0.192
11.8
2 Dimming Daylighting Lighting 0 23,551 0 $2,438 12,251 $0.367 -
$0.490
32.3 Implement when
other major work is
completed (HVAC)3 Lighting Occupancy and
Vacancy Sensor Controls
Lighting (2) 32,868 0 $3,403 17,098 $0.526 -
$0.702
46.3
4 Heat Pump Water Heater Plumbing
System
(7) (9,054) 1,479 $341 8,708 $0.024 -
$0.029
10.2 Implement at end of
system life
5A Window Replacement:
U-factor 0.29, SHGC 0.32
Building
Envelope
36 60,990 (141)$6,189 30,451 $0.042 -
$0.179
16.2 Implement at end of
system life
5B Window Replacement:
U-factor 0.36, SHGC 0.38
Building
Envelope
27 44,278 (141)$4,463 21,757 $0 -
$0.116
8.5
1 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to
have a life of 10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either
15 years for smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-
fired equipment.
Estimated Savings for EEM Bundles
Estimated energy savings from implementing all recommended measures are shown in the following charts. The first
chart shows the savings in annual EUI, the second chart shows the savings in annual energy cost, and the third chart
shows the savings in annual carbon emissions. The columns are described as follows:
• Non-Mechanical Strategies: Implement EEMs 2-4 and 5A to improve lighting, building envelope, and domestic
hot water systems.
• Mechanical Strategy 1A: Implement EEM 1A to improve mechanical systems by installing ground source heat
pumps.
• Mechanical Strategy 1A Plus Non-Mechanical Strategies: Implement EEMs 1A, 2-4, and 5A to improve
mechanical, lighting, building envelope and domestic hot water systems.
• Mechanical Strategy 1B: Implement EEM 1B to improve mechanical systems by installing air source heat pumps.
• Mechanical Strategy 1B Plus Non-Mechanical Strategies: Implement EEMs 1B, 2-4, and 5A to improve
mechanical, lighting, building envelope and domestic hot water systems.
Energy Efficiency Measures Energy Efficiency Measures
Predicted Annual EUI Savings
kB
T
U
/
f
t
2/y
r
Predicted Annual Energy Cost Savings
Predicted Annual Carbon Emissions Savings
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City Hall44 45City of Ames Energy Audit City of Ames Energy AuditCity Hall
Appendix: Energy Analysis Inputs
Energy analysis inputs and assumptions are described below. This information is based on building walk-through
observations, information from City staff, available drawings, and standard design practices based on building
vintage and program type.
Program Type & Building Geometry
Operations
HVAC Controls
Ventilation Requirements
Appendix: Energy Analysis Inputs
25
City Hall46 47City of Ames Energy Audit City of Ames Energy AuditCity Hall
Appendix: Energy Analysis Inputs
Lighting
Service Hot Water & Other Loads
Appendix: Energy Analysis Inputs
Envelope
Fenestration
26
49City of Ames Energy Audit
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Ames Public Library
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Ames Public Library50 51City of Ames Energy Audit City of Ames Energy AuditAmes Public Library
Facility Description
Building Contact Information
Building Name Ames Public Library
Address 515 Douglas Avenue
Ames, IA 50010
Building Owner City of Ames
Key Contact Bo Duckett, Library Building Maintenance Supervisor
Building Characteristics
General
Year of original construction: 1904
Building Climate Zone: 5A
Gross floor area: 101,800 sq.ft.
Total conditioned area: 101,800 sq.ft.
Total number of floors: 2
Conditioned floors above grade: 2
Conditioned floors below grade: 0
Use Type
Primary building use type: Library/Assembly
Secondary building use type: N/A
Major Renovations
1907 Expansion/addition
1940 Expansion/addition
2014 Renovation and significant addition
Operations
Typical weekly occupancy: Sunday 1:00 pm to 5:00 pm
Monday through Thursday 9:00 am to 9:00 pm
Friday and Saturday 9:00 am to 6:00 pm
Typical annual occupancy: 52 weeks/year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
The exterior walls have varying levels of thermal performance, as to be
expected given the various vintages ranging from 1904 to 2014. Both the
existing brick and existing precast walls dating back to the 1904 and 1940’s
construction include concrete masonry units and were renovated in 2014
with new 2” rigid insulation and new gypsum wall board. The 2014 exterior
walls include metal panels and cast stone cladding with rigid insulation levels
varying from R-18.6 to R-21.
The window to wall ratio is approximately 27%, and there are four primary
window types. The 1904 windows are single-glazed wood-framed double-
hung windows with storm windows; although they previously were operable,
they now function as fixed windows. The 1940 windows are single-glazed
steel-framed fixed windows. The 2014 windows and curtain wall system are
double-glazed aluminum-framed fixed windows. The main entries are glazed
doors, while the garage has an opaque insulated sectional overhead door.
The existing roof was renovated in 2014 to align with the performance of
the new addition roof. Both the renovated and new roof include a white TPO
membrane and rigid insulation with R-value performance of R-37.2 on top of
the roof sheathing, air barrier, and roof deck.
Lighting System
Lighting systems throughout the building are LED, utilizing modern lighting
controls. A variety of fixture types include suspended direct-indirect
fixtures, troffer (lay-in) ceiling fixtures, and various others. Lighting control
capabilities include daylighting, scheduling, occupancy/vacancy, and
dimming.
HVAC Systems
The building HVAC systems generally consist of a central plant serving air
handling units, chilled beams, and blower coils. Heating water, chilled water,
and chilled beam water provide conditioning to the equipment.
The central plant provides chilled water from an air-cooled chiller mounted
on the roof of the building. Two (2) high-efficiency natural gas-fired boilers
provide heating hot water to the building. A water-to-water heat pump is
used to generate reheat water (hot water) during the cooling season. The
central plant also includes pumps, piping accessories, and controls. Both
heating and chilled water systems utilize a 30-percent glycol solution for
freeze protection.
North Elevation
East Elevation
Roof
Interior Lighting
Networked Lighting Control
28
Ames Public Library52 53City of Ames Energy Audit City of Ames Energy AuditAmes Public Library
Facility Description
The majority of the addition area (south portion of the building) is served
by chilled beams to provide terminal heating and sensible cooling. Latent
cooling and primary air for this area are provided by a dedicated outdoor
air system (DOAS) unit on the roof, which is equipped with energy recovery
and provides low dew point supply air. The larger gathering spaces in the
addition are served by blower coils fed with outdoor air from the DOAS unit.
Chilled water and heating water serve the DOAS unit and blower coils, and
chilled beam water and heating water serve the chilled beams.
A variable-air-volume (VAV) air handling unit generally serves the original
portion of the building (north portion of the building). Chilled water and
heating water serve the air handling unit and heating water provides reheat
for terminal units (VAV boxes).
Unit heaters serve support spaces, including storage areas, library bus
parking, etc.
The entire building is served by a direct digital control (DDC) building
automation system.
Plumbing Systems
Domestic hot water for the building is provided by two (2) on-demand natural
gas-fired water heaters serving a storage tank.
Chilled Water Pumps
Air Handling Unit
DOAS and Air-Cooled ChillerGas-Fired Boilers
Gas-Fired Water Heaters
Heat Recovery Chiller
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on March 19, 2025.
Observations
Building Envelope
• The new vestibule door experiences issues due to building
pressurization; recommend resolving this issue through building control
system.
• 1904 wood windows must remain in place given the historic
preservation requirements. The storm windows help improve the thermal
performance of the window assembly.
• 1940 steel windows experience noticeable thermal bridging. Caulk
condition also appears to be poor.
• Several cloudy windows with condensation were observed in the 2012
addition. These IGUs should be replaced over time as needed to maintain
window performance.
Lighting Systems
• Lighting system is modern and does not have meaningful opportunity for
efficiency improvement – consideration of replacement scheduling may
be appropriate.
HVAC Systems
• Building is configured well for future flexibility due to operating
temperatures and DOAS unit.
• Building is not a likely candidate for geothermal (ground-coupled heat
exchanger) due to limited site size.
Plumbing Systems
• Depending on hot water needs, storage tank may provide more capacity
than required.
Typical Wood and Storm Window
Typical Steel Window
Cloudy Aluminum-Framed Window
29
Ames Public Library54 55City of Ames Energy Audit City of Ames Energy AuditAmes Public Library
Monthly Electric Usage
The monthly electrical consumption profile shows a typical pattern of higher usage in the summer than in the
winter due to cooling loads.
Monthly Natural Gas Usage
The monthly natural gas consumption profile shows a typical pattern of higher usage in the winter than in the
summer due to natural gas serving the heating loads. Natural gas consumption in the summer is attributed to
domestic hot water heating.
Overview
Metered energy data from January 2020 through November 2024 was collected during the audit and is
documented below. The building is operating efficiently, and there are limited opportunities for reducing energy
consumption. However, the building uses natural gas for heating and water heating, and there are opportunities to
reduce carbon emissions through converting the systems to efficient electric systems.
Utility Bill Analysis
38.4
kBtu/ft2/yr
Energy Use
Annual Energy Use Intensity (EUI)
Based on the measured energy use between
December 2023 and November 2024, the
building has an energy use intensity of 38.4
kBtu/sq.ft./yr. 76% of the building’s annual
energy use is attributed to electricity, while
the remaining 24% is attributed to natural
gas.
Monthly Natural Gas Use
Dec 2023-Nov2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Monthly Electric Use
Dec 2023-Nov 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Annual Energy Use Intensity
Dec 2023-Nov 2024
Electric
Natural Gas
Electric12/23-11/24
Electric Baseline1/20-12/20
kW
h
Natural Gas12/23-11/24
Natural Gas Baseline
1/20-12/20
Th
e
r
m
s
Dec 2023 - Nov 2024
Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 20240
50,000
100,000
0
1,000
2,000
3,000
Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 2024
0
20
40
Energy Cost
Annual Energy Cost
Based on the measured energy use and utility bills between December 2023 and November 2024, the building’s
annual energy cost is $98,243. 92% of the building’s annual energy cost is attributed to electricity, while the
remaining 8% is attributed to natural gas. Energy costs have fluctuated only slightly over the past few years.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use between January 2023 and December 2023, the building’s annual carbon
emissions is approximately 463 mt-CO2e/yr. About 87% of the building’s annual carbon emissions is attributed to
electricity, 13% is attributed to natural gas.
Utility Bill Analysis
$98,243/yr
Annual Energy Cost Comparison
2021-2023
Annual Carbon Emissions
2023
Annual Energy Costs
Dec 2023-Nov 2024
Electric
Natural Gas
Electric
Natural Gas
Electric
Natural Gas
Me
t
r
i
c
T
o
n
s
C
O
2e
Co
s
t
2023
0
200
400
600
2021 2022 2023
0
$50,000
$100,000
$150,000
30
Ames Public Library56 57City of Ames Energy Audit City of Ames Energy AuditAmes Public Library
The building ranks in the 83rd percentile to 657 other peer library buildings in the B3 Benchmarking tool (17%
of library buildings have better performance). This indicates that the building is performing well from an energy
efficiency perspective.
The B3 Benchmark Rating is an easy to understand 1 to 5 star-ranking system. For the energy benchmark, it is
based on the ratio of actual kBtu per square foot compared to the benchmark kBtu per square foot model. A rating
higher than 2 1/2 stars means the building is performing better than expected. A rating less than 2 1/2 stars
indicates greater potential for savings.
Benchmarking
B3 Benchmarking Comparison
Be
n
c
h
m
a
r
k
i
n
g
R
a
t
i
n
g
0
1
3
2
4
5
0 4 12 20 24 32 40 44 52 56 64 68 76 80 88 92 100
Peer Rating
8 16 28 36 48 60 72 84 96
Methodology
The energy use of the building and the energy efficiency measures were analyzed using a detailed energy model
and tuned to the actual overall energy consumption of the facility. The detailed energy model models the hourly
energy use of all components of the building over a year. The inputs to the energy model were obtained through
conversations with city staff, the facility walk through, and documents provided by the city staff. When information
was not available through these methods, building characteristics were assumed based on building vintage and
engineering judgment.
Energy Use Characterization
The following graph shows the modeled energy use of the building broken down by end use. The heating and
cooling systems demonstrated efficient operation, and lighting and equipment are the dominant energy uses in the
building.
Energy Analysis
Electricity Natural GasEUI(kBtu/sq.ft./yr)
kB
T
U
/
f
t
2
/
y
r
Existing
Energy Use Characterization by Energy End Use
0
5
10
15
25
40
45
Total 41.8
Interior Equipment 9.0
Interior Lighting 12.2
Domestic Hot Water 1.4
Pumps 1.4
Fans 2.7
Cooling 4.7
Heating 10.3
20
30
35
31
Ames Public Library58 59City of Ames Energy Audit City of Ames Energy AuditAmes Public Library
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1 - Replace Air-Cooled Chiller with Air-to-Water Heat Pump(s)
• Existing Condition: Air-cooled chiller provides chilled water for building.
• Proposed Energy Efficiency Measure: Air-to-water heat pump(s) provide chilled water for building during
the cooling season, and provide heating water for building during heating season (become primary source of
heating with boilers serving as secondary source of heating).
• Recommendation for Implementation: Consider utilizing new equipment configuration when air-cooled chiller
replacement is required – expected to be approximately ten years.
EEM 2 - Heat Pump Water Heater
• Existing Condition: Domestic hot water generated by on-demand natural gas-fired water heaters.
• Proposed Energy Efficiency Measure: Heat pump water heater (may still serve storage tank if determined to
be necessary for capacity).
• Recommendation for Implementation: Consider when replacement of water heaters is necessary.
EEM 3A & 3B - 1940 Window Replacement
• Existing Condition: The 1940 steel-framed single-glazed windows in the north vestibule are not energy efficient.
• Proposed Energy Efficiency Measure: Replace the 1940 steel-framed windows with a high-performing
thermally-broken window assembly that is better than current energy code minimums. EEM 3A evaluates the
impact of a window assembly with a U-factor of 0.29 and a Solar Heat Gain Coefficient (SHGC) of 0.32, while
EEM 3B evaluates the impact of a window assembly with a U-factor of 0.36 and a SHGC of 0.38.
• Recommendation for Implementation: Recommend replacing the windows the next time window repair is
required. EEM 3A is recommended as a higher-performance option, provided that the cost difference between
the two options is minimal. Additionally, further review is required to confirm that these windows are not subject
to historic preservation requirements. If historic preservation requirements are applicable, consider installing a
storm window instead.
Estimated Costs For Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate EEM Incremental Cost
Low High
1 Mechanical System Replacement with Air
to Water HP
Direct air-cooled chiller replacement $570,000 $0 $285,000 $570,000
2 Heat Pump Water Heater Direct water heater replacements $7,500 $800 $1,000 $3,500
3A 1940 Window Replacement: U-factor 0.29,
SHGC 0.32
Energy Code-Compliant Window Re-
placement
$16,740 $0 $1,672 $7,191
3B 1940 Window Replacement: U-factor 0.36,
SHGC 0.38
Energy Code-Compliant Window Re-
placement
$16,740 $0 $0 $3,344
Energy Efficiency Measures
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved1
($/kgCO2e)
Average
Simple
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms Energy
Cost
CO2
Emissions
(kgCO2e)
1 Replace Air-Cooled Chiller
with Air-to-Water Heat
Pump(s)
HVAC
System
0 (141,185) 11,543 $(4,630) 31,274 $0.456 -
$0.911
N/A Reevaluate options
prior to end of system
life (in approximately
5-10 years)
2 Heat Pump Water Heater Plumbing
System
(4)(8,602) 1,095 $57 5,459 $0.018 -
$0.064
N/A Implement at end of
system life
3A 1940 Window Replacement:
U-factor 0.29, SHGC 0.32
Building
Envelope
1 643 118 $170 1,405 $0.040 -
$0.171
26.1 Implement at end of
system life
3B 1940 Window Replacement:
U-factor 0.36, SHGC 0.38
Building
Envelope
1 495 88 $131 1,056 $0 -
$0.106
12.8
1 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to
have a life of 10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either
15 years for smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-
fired equipment.
Estimated Savings for EEM Bundles
Estimated energy savings from implementing all recommended measures are shown in the following charts. The first
chart shows the savings in annual EUI, the second chart shows the savings in annual energy cost, and the third chart
shows the savings in annual carbon emissions. The columns are described as follows:
• Non-Mechanical Strategies: Implement EEMs 2 and 3A to improve the building envelope and domestic hot
water systems.
• Mechanical Strategy 1: Implement EEM 1 to improve mechanical systems by installing an air-to-water-heat-
pump.
• Mechanical Strategy 1 Plus Non-Mechanical Strategies: Implement EEMs 1, 2 and 3A to improve mechanical,
building envelope, and domestic hot water systems.
Energy Efficiency Measures
32
Ames Public Library60 61City of Ames Energy Audit City of Ames Energy AuditAmes Public Library
Energy Efficiency Measures
Predicted Annual EUI Savings
kB
T
U
/
f
t
2/y
r
Predicted Annual Energy Cost Savings
Predicted Annual Carbon Emissions Savings
kg
C
O
2e
Non-Mechanical Strategies Mechanical Strategy 1 Mechanical Strategy 1 Plus
Non-Mechanical Strategies
Non-Mechanical Strategies Mechanical Strategy 1 Mechanical Strategy 1 Plus
Non-Mechanical Strategies
Non-Mechanical Strategies Mechanical Strategy 1 Mechanical Strategy 1 Plus
Non-Mechanical Strategies
Appendix: Energy Analysis Inputs
HVAC Controls
Operations
Program Type & Building Geometry
Energy analysis inputs and assumptions are described below. This information is based on building walk-through
observations, information from City staff, available drawings, and standard design practices based on building
vintage and program type.
33
Ames Public Library62 63City of Ames Energy Audit City of Ames Energy AuditAmes Public Library
Appendix: Energy Analysis Inputs
Ventilation Requirements
Lighting
Service Hot Water & Other Loads
Appendix: Energy Analysis Inputs
Fenestration
Envelope
34
65City of Ames Energy Audit
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Fire Station 1
35
Fire Station 166 67City of Ames Energy Audit City of Ames Energy AuditFire Station 1
Facility Description
Building Contact Information
Building Name Fire Station 1
Address 1300 Burnett Avenue
Ames, IA 50010
Building Owner City of Ames
Key Contact Dave Folkmann, Fire Department Shift Commander
Building Characteristics
General
Year of original construction: 1980
Building Climate Zone: 5A
Gross floor area: 12,602 sq.ft.
Total conditioned area: 12,602 sq.ft.
Total number of floors: 2
Conditioned floors above grade: 2
Conditioned floors below grade: 0
Use Type
Primary building use type: Fire Station
Secondary building use type: N/A
Major Renovations
~2010 Roof renovation
2010s to 2020s Second floor interior renovation
2021 HVAC modifications
2025 Roof repairs and additional insulation
Operations
Typical weekly occupancy: 7 days/week, 24-hours per day
Typical annual occupancy: 52 weeks/year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
The exterior walls are concrete masonry units with face brick cladding. The
walls in the living areas are finished with gypsum board and there appears to
be batt insulated between furring behind the gypsum board.
The windows are double-glazed aluminum-framed assemblies that are
original to the building. The punched windows in the living areas have a fixed
lite at the top and an operable lite at the bottom, while other windows are
fully fixed. The main entrance features a glazed entry door, and the app bay
features opaque insulated sectional doors to the north, and glazed sectional
doors to the south. The glazed sectional doors were installed around 2015
to provide more visibility between the fire station and the community.
The roof is a flat membrane roof with approximately 3.5” of rigid insulation
above the roof deck.
Lighting System
Lighting systems throughout the building utilize LED fixtures. Lighting
controls are provided for daylight dimming and occupancy/vacancy as
required by code.
HVAC Systems
Occupied areas of the building (areas other than the apparatus bay) are
served by residential-style natural gas-fired furnaces and air-cooled
condensing units. These furnaces are equipped with zoning controls. A
single return fan serves all furnaces. Outdoor air is introduced to furnaces
through a gravity intake, but units do not have economizer capabilities.
Dedicated exhaust fans serve select areas of the building.
The apparatus bay is equipped with dedicated exhaust and heating systems.
Engine exhaust is provided along with gas detection. Heat for the space is
provided by natural gas-fired unit heaters and natural gas-fired furnaces.
Plumbing Systems
Domestic hot water is generated by a high-efficiency natural gas-fired water
heater.
South Elevation
Apparatus Bay Lighting
Exhaust Capture System
Exterior Lighting
Gas-Fired FurnacesHorizontal Furnace in Bay In-Line Return Fan
36
Fire Station 168 69City of Ames Energy Audit City of Ames Energy AuditFire Station 1
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on March 11, 2025.
Observations
Building Envelope
• After the walkthrough, the roof experienced leaking in 2025 due to
the rubber shrinking and pulling from the parapet walls. The roof was
repaired.
• The windows are approaching their end of life, but appear in adequate
condition considering their age.
Lighting Systems
• Lighting system is modern and does not have meaningful opportunity for
efficiency improvement.
HVAC Systems
• Appears that there may be building pressure control issues with
difference between listed outdoor air and exhaust air flow rates (likely
results in fairly negative building).
• Appears sizing of some units should require economizer based on
current energy code requirements.
Plumbing Systems
• Condensing water heater is appropriate given expected hot water usage
for facility.
Typical Window
Monthly Electric Usage
The monthly electrical consumption profile shows a typical pattern of higher usage in the summer than in the
winter due to cooling loads. The increase in the summer is not pronounced due to only a portion of the building
being cooled.
Monthly Natural Gas Usage
The monthly natural gas consumption profile shows a typical pattern of higher usage in the winter than in the
summer due to natural gas serving the heating loads. Natural gas consumption in the summer is due to hot water
heating.
Overview
Metered energy use from February 2020 through December 2024 was collected during the audit and is
documented below. The apparatus bays are heated only, and natural gas used for heating is the dominant energy
source of the building.
Utility Bill Analysis
54.1
kBtu/ft2/yr
Energy Use
Annual Energy Use Intensity (EUI)
Based on measured energy use between
June 2023 and May 2024, the building has
an energy use intensity of 54.1 kBtu/sq.ft./
yr. 41% of the building’s annual energy use
is attributed to electricity and the remaining
59% of the budling’s annual energy use is
attributed to natural gas.
Monthly Natural Gas Use
Jan 2023-Dec 2023 Compared to Jan 2021-Dec 2021, Weather Normalized
Monthly Electric Use
Jan 2023-Dec 2023 Compared to Jan 2021-Dec 2021, Weather Normalized
Annual Energy Use Intensity
Jun 2023-May 2024
Electric
Natural Gas
Electric1//23-12/23
Electric Baseline1/21-12/21
kW
h
Natural Gas6/23-5/24
Natural Gas Baseline
1/21-12/21
Th
e
r
m
s
Jun 2023 - May 2024
Jan 2023 Feb 2023 Mar 2023 Apr 2023 May 2023 Jun 2023 Jul2023 Aug 2023 Sep 2023 Oct 2023 Nov 2023 Dec 20230
5,000
0
500
1,000
1,500
0
20
60
40
10,000
Jan 2023 Feb 2023 Mar 2023 Apr 2023 May 2023 Jun 2023 Jul2023 Aug 2023 Sep 2023 Oct 2023 Nov 2023 Dec 2023
37
Fire Station 170 71City of Ames Energy Audit City of Ames Energy AuditFire Station 1
Energy Cost
Annual Energy Cost
Based on the measured energy use and utility bills between June 2023 and May 2024, the building’s annual energy
cost is $11,874. 71% of the building’s annual energy cost is attributed to electricity, while the remaining 29%
of the building’s annual energy cost is attributed to natural gas. Electric energy costs have been consistent over
the past several years, while natural gas costs were approximately 50% higher in 2022, bringing the total annual
energy cost to $16,130.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use between January 2023 and December 2023, the building’s annual carbon
emissions is 69.6 mt-CO2e/yr. About 63% of the building’s annual carbon emissions is attributed to natural gas,
and 37% is attributed to electricity.
Utility Bill Analysis
$11,874/yr
Annual Energy Cost Comparison
2021-2023
Annual Carbon Emissions
2023
Annual Energy Costs
Jun 2023-May 2024
Electric
Natural Gas
Electric
Natural Gas
Electric
Natural Gas
Me
t
r
i
c
T
o
n
s
C
O
2e
Co
s
t
2023
0
20
60
80
2021 2022 2023
0
$5,000
$10,000
$20,000
$15,000
40
The building ranks in the 83 percentile to 1000 other peer fire station buildings in the B3 Benchmarking tool (17%
of fire station buildings have better performance). This indicates that the fire station has good energy efficiency
performance.
The B3 Benchmark Rating is an easy to understand 1 to 5 star-ranking system. For the energy benchmark, it is
based on the ratio of actual kBtu per square foot compared to the benchmark kBtu per square foot model. A rating
higher than 2 1/2 stars means the building is performing better than expected. A rating less than 2 1/2 stars
indicates greater potential for savings.
Benchmarking
B3 Benchmarking Comparison
Be
n
c
h
m
a
r
k
i
n
g
R
a
t
i
n
g
0
1
3
2
4
5
0 4 12 20 24 32 40 44 52 56 64 68 76 80 88 92 100
Peer Rating
8 16 28 36 48 60 72 84 96
38
Fire Station 172 73City of Ames Energy Audit City of Ames Energy AuditFire Station 1
Methodology
The energy use of the building and the energy efficiency measures were analyzed using a detailed energy model
and tuned to the actual overall energy consumption of the facility. The detailed energy model models the hourly
energy use of all components of the building over a year. The inputs to the energy model were obtained through
conversations with city staff, the facility walk through, and documents provided by the city staff. When information
was not available through these methods, building characteristics were assumed based on building vintage and
engineering judgment.
Energy Use Characterization
The following graph shows the modeled energy use of the building broken down by end use. Heating energy makes
up 56% of the energy use followed by fans and lighting. The high proportion of heating energy use is due to the
significant heating loads of the apparatus bay, and that the apparatus bay has no cooling. Reducing the heating
energy will have the biggest impact on the building’s energy consumption.
Energy Analysis
Electricity Natural GasEUI(kBtu/sq.ft./yr)
kB
T
U
/
f
t
2
/
y
r
Existing
Energy Use Characterization by Energy End Use
0
10
30
50
50
Total 56.7
Interior Equipment 3.1
Interior Lighting 6.2
Domestic Hot Water 2.9
Fans 11.2
Cooling 1.7
Heating 31.6
20
40
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1A - Air-source heat pump and electric resistance heat
• Existing Condition: Natural gas-fired furnaces and air-cooled condensing units (air conditioners).
• Proposed Energy Efficiency Measure: Air-source heat pumps paired with residential-style air handlers with
supplemental electric heating coils.
• Recommendation for Implementation: Consider implementation when existing furnaces or condensing units
require replacement.
EEM 1B - Air-source heat pump and natural-gas heat
• Existing Condition: Natural gas-fired furnaces and air-cooled condensing units (air conditioners).
• Proposed Energy Efficiency Measure: Air-source heat pumps paired with high-efficiency natural gas-fired
furnaces.
• Recommendation for Implementation: Consider implementation when existing furnaces or condensing units
require replacement.
EEM 2 - Hybrid Heat Pump Water Heater
• Existing Condition: Domestic hot water generated by standard efficiency natural gas-fired water heater.
• Proposed Energy Efficiency Measure: Install hybrid heat pump water heater.
• Recommendation for Implementation: Consider installation when existing water heater requires replacement.
EEM 3A & 3B - Window Replacement
• Existing Condition: The double-glazed aluminum-framed windows are original to the building.
• Proposed Energy Efficiency Measure: Replace windows with a high-performing thermally-broken window
assembly that is better than current energy code minimums. EEM 3A evaluates the impact of a window
assembly with a U-factor of 0.29 and a Solar Heat Gain Coefficient (SHGC) of 0.32, while EEM 3B evaluates
the impact of a window assembly with a U-factor of 0.36 and a SHGC of 0.38.
• Recommendation for Implementation: Recommend implementing when windows reach their end of life, in
approximately 5 to 10 years. EEM 3A is recommended as a higher-performance option, provided that the cost
difference between the two options is minimal. The performance of EEM 3B is typical of a high-performing
double-pane window, while the performance of EEM 3A is achievable with either a higher-performing double-
pane window or a triple-pane window. Triple pane windows offer additional acoustic advantages and could be
considered for the dorm rooms.
EEM 4 – Increase Roof Insulation
• Existing Condition: The existing roof was renovated around 2003 and has approximately 3.5” of rigid insulation.
• Proposed Energy Efficiency Measure: Add additional insulation to increase the overall thermal performance to
R-30.
• Recommendation for Implementation: Recommend implementation when the roof membrane reaches its end
of life, in approximately 10 years. Based on information provided, an additional 1” to 2” of polyiso insulation
in the roof assembly could achieve R-30 performance. Existing insulation thickness and condition should be
further reviewed and confirmed prior to the roof upgrade to verify additional insulation levels to meet R-30
performance.
Energy Efficiency Measures
39
Fire Station 174 75City of Ames Energy Audit City of Ames Energy AuditFire Station 1
Estimated Costs for Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate EEM Incremental Cost
Low High
1A Air-source heat pump and electric
resistance heat
Direct replacement of existing furnace
and condensing unit.
$45,000 $60,000 $12,000 $27,000
1B Air-source heat pump and natural-gas heat Direct replacement of existing furnace
and condensing unit.
$45,000 $52,500 $4,500 $12,000
2 Hybrid Heat Pump Water Heater Direct replacement of existing natural
gas-fired water heater.
$3,000 $400 $5,350 $6,100
3A Window Replacement:
U-factor 0.29, SHGC 0.32
Energy Code-Compliant Window Re-
placement
$30,132 $0 $3,013 $12,957
3B Window Replacement:
U-factor 0.36, SHGC 0.38
Energy Code-Compliant Window Re-
placement
$30,132 $0 $0 $6,026
4 Roof Insulation Increase Replace roof membrane without adding
insulation
$23,001 $0 $16,109 $28,374
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved1
($/kgCO2e)
Average
Simple
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms Energy
Cost
CO2
Emissions
(kgCO2e)
1A Air-source heat pump and
electric resistance heat
HVAC
System
(61,326) 4,347 $(2,589) 7,534 $0.106 -
$0.239
N/A Implement at end of
system life
1B Air-source heat pump and
natural-gas heat
HVAC
System
(29,218) 2,977 $(450) 11,808 $0.025 -
$0.068
N/A
2 Hybrid Heat Pump Water
Heater
Plumbing
System
(2) (2,765) 368 $33 1,900 $0.282 -
$0.321
N/A Implement at end of
system life
3A Window Replacement: U-factor 0.29, SHGC 0.32 Building Envelope 0 449 419 $404 4,034 $0.025 - $0.107 19.8 Implement at end of system life
3B Window Replacement: U-factor 0.36, SHGC 0.38 Building Envelope 0 186 364 $334 3,403 $0 - $0.059 9.0
4 Increase Roof Insulation Building
Envelope
0 50 119 $104 1,102 $0.487 -
$0.858
N/A Implement at end of
system life
1 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to
have a life of 10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either
15 years for smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-
fired equipment.
Energy Efficiency Measures
Estimated Savings for EEM Bundles
Estimated energy savings from implementing all recommended measures are shown in the following charts. The first
chart shows the savings in annual EUI, the second chart shows the savings in annual energy cost, and the third chart
shows the savings in annual carbon emissions. The columns are described as follows:
• Non-Mechanical Strategies: Implement EEMs 2, 3A, and 4 to improve the building envelope and domestic hot
water systems.
• Mechanical Strategy 1A: Implement EEM 1A by installing air-source heat pumps and electric resistance heat to
replace furnaces and condensing units.
• Mechanical Strategy 1A Plus Non-Mechanical Strategies: Implement EEM 1A by installing air-source heat
pumps with electric resistance heat plus EEMs 2, 3A and 4.
• Mechanical Strategy 1B: Implement EEM 1B by installing air-source heat pumps and natural gas-fired furnaces
to replace furnaces and condensing units.
• Mechanical Strategy 1B Plus Non-Mechanical Strategies: Implement EEM 1B by installing air-source heat
pumps and natural gas-fired furnaces plus EEMs 2, 3A, and 4.
Energy Efficiency Measures
Predicted Annual EUI Savings
kB
T
U
/
f
t
2/y
r
40
Fire Station 176 77City of Ames Energy Audit City of Ames Energy AuditFire Station 1
Predicted Annual Carbon Emissions Savings
kg
C
O
2e
Energy Efficiency Measures
Predicted Annual Energy Cost Savings
HVAC Controls
Operations
Program Type & Building Geometry
Appendix: Energy Analysis Inputs
Energy analysis inputs and assumptions are described below. This information is based on building walk-through
observations, information from City staff, available drawings, and standard design practices based on building
vintage and program type.
41
Fire Station 178 79City of Ames Energy Audit City of Ames Energy AuditFire Station 1
Appendix: Energy Analysis Inputs
Ventilation Requirements
Lighting
Service Hot Water & Other Loads
Appendix: Energy Analysis Inputs
Fenestration
Envelope
42
81City of Ames Energy Audit
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Fire Station 3
43
Fire Station 382 83City of Ames Energy Audit City of Ames Energy AuditFire Station 3
Facility Description
Building Contact Information
Building Name Fire Station 3
Address 2400 S Duff Avenue
Ames, IA 50010
Building Owner City of Ames
Key Contact Dave Folkmann, Fire Department Shift Commander
Building Characteristics
General
Year of original construction: 2002
Building Climate Zone: 5A
Gross floor area: 7,599 sq.ft.
Total conditioned area: 7,599 sq.ft.
Total number of floors: 1
Conditioned floors above grade: 1
Conditioned floors below grade: 0
Use Type
Primary building use type: Fire Station
Secondary building use type: N/A
Major Renovations
2024 Partial mechanical system renovation
Operations
Typical weekly occupancy: 7 days/week, 24-hours/day
Typical annual occupancy: 52 weeks/year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
The exterior walls of the apparatus bay are concrete masonry units with face
brick cladding. The exterior walls for the living areas appear to be stud walls
with batt insulation, with face brick cladding and gypsum board interior finish.
The windows are double-glazed aluminum-framed assemblies that are
original to the building. The majority of windows are operable, with the
exception of the glazed corner of the day room and vestibule windows. The
main entrance features a glazed entry door, and the app bay features opaque
insulated sectional doors to the east, and glazed sectional doors to the west.
The glazed sectional doors were installed around 2015-2016 to provide
more visibility between the fire station and the community.
The roof is a flat black membrane roof, assumed to have rigid insulation
above the roof deck as typical of design and construction practices in the
early 2000’s.
Lighting System
Lighting systems throughout the building utilize LED fixtures. Lighting
controls are provided for daylight dimming and occupancy/vacancy as
required by code.
HVAC Systems
Occupied areas of the building (areas other than the apparatus bay) are
served by residential-style natural gas-fired furnaces and air-cooled
condensing units. An energy recovery ventilator provides outdoor air and
exhaust to the furnaces. Dedicated exhaust fans serve select areas of the
building.
The apparatus bay is equipped with dedicated exhaust and heating systems.
Engine exhaust is provided along with gas detection. Hydronic in-floor heat
is the primary source of heating for the space, with hot water generated by a
natural gas-fired boiler. Secondary heat for the space is provided by natural
gas-fired unit heaters.
Plumbing Systems
Domestic hot water is generated by a standard efficiency natural gas-fired
water heater.
Typical Exterior Wall and Window
Energy Recovery Ventilator
Exhaust Capture System
Exterior Lighting with LED Lamp
Gas-Fired Unit Heaters
Kitchen Lighting
44
Fire Station 384 85City of Ames Energy Audit City of Ames Energy AuditFire Station 3
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on March 11, 2025.
Observations
Building Envelope
• The seal was broken on a window in the day room, causing a cloudy
window.
• Condensation on the glazed sectional doors of the app bay was
observed and should be further monitored. This condition can be caused
by warmer, more humid indoor conditions during cold, low-humidity days.
Recommend replacement if condensation appears within the IGU.
• Noticeable thermal bridge where roof structure of living quarters
intersects with wall of apparatus bay, as shown by dark purple band in
corresponding image.
Lighting Systems
• Lighting system is modern and does not have meaningful opportunity for
efficiency improvement – consideration of replacement scheduling may
be appropriate.
HVAC Systems
• Only one of two heating water boilers is currently operational for in-floor
heating system.
Plumbing Systems
• Because of residential, cooking, and laundry operations in building, more
significant impact to energy use from standard efficiency water heater
than for many other City facilities.
Day Room Window, Broken Seal
Condensation on App Bay Doors
Thermal Bridge in Apparatus Bay
Boilers (One Disabled)
Water Heater
Monthly Electric Usage
The monthly electrical consumption profile shows higher usage in the winter, indicating use of electric heat.
However, the implementation of a project to eliminate electric heat that was implemented after June 2024 likely
has reduced the winter electricity consumption.
Monthly Natural Gas Usage
The monthly natural gas consumption profile shows a typical pattern of higher usage in the winter than in the
summer due to natural gas serving the heating loads. Natural gas consumption in the summer is due to domestic
hot water heating.
Overview
Metered energy data from December 2019 through June 2024 was collected during the audit and is documented
below. The City staff shared that a project was completed after June 2024 to reduce electric heating in the
building, however utility following the completion of the project was not available.
Utility Bill Analysis
72.6
kBtu/ft2/yr
Energy Use
Annual Energy Use Intensity (EUI)
Based on measured energy use between
June 2023 and May 2024, the building has
an energy use intensity of 72.6 kBTU/sq.ft/
yr. 34% of the building’s annual energy use is
attributed to electricity, while the remaining
66% is attributed to electricity.
Monthly Natural Gas Use
Jun 2023-May 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Monthly Electric Use
Jun 2023-May 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Annual Energy Use Intensity
Jun 2023-May 2024
Electric
Natural Gas
Electric
6/23-6/24
Electric Baseline1/20-12/20
kW
h
Natural Gas6/23-5/24
Natural Gas Baseline
1/20-12/20
Th
e
r
m
s
Jun 2023 - May 2024
4,000
6,000
0
500
1,000
1,500
0
50
100
2,000
0 Jun 2023 Jul 2023 Aug 2023 Sep 2023 Oct 2023 Nov 2023 Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024
0 Jun 2023 Jul 2023 Aug 2023 Sep 2023 Oct 2023 Nov 2023 Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024
45
Fire Station 386 87City of Ames Energy Audit City of Ames Energy AuditFire Station 3
Energy Cost
Annual Energy Cost
Based on the measured energy use and utility bills between June 2023 and May 2024, the building’s annual energy
cost is $8,850. 65% of the building’s annual energy cost is attributed to electricity, while the remaining 35% of the
building’s annual energy cost is attributed to natural gas. Electricity costs have stayed stable over the base several
years, but natural gas costs were significantly higher in 2022 bringing the total annual energy cost to $11,880.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use between January 2023 and December 2023, the building’s annual carbon
emissions is approximately 52.4 mt-CO2e/yr. About 55% of the building’s annual carbon emissions is attributed to
electricity and 45% is attributed to natural gas.
Utility Bill Analysis
$8,850/yr
Annual Energy Cost Comparison
2021-2023
Annual Carbon Emissions
2023
Annual Energy Costs
Jun 2023-May 2024
Electric
Natural Gas
Electric
Natural Gas
Electric
Natural Gas
Me
t
r
i
c
T
o
n
s
C
O
2e
Co
s
t
2023
0
20
40
60
2021 2022 2023
0
$5,000
$10,000
$15,000
The building ranks in the 77 percentile to 1000 other peer fire station buildings in the B3 Benchmarking tool (23%
of fire station buildings have better performance). This indicates that there are moderate opportunities for reducing
energy consumption.
The B3 Benchmark Rating is an easy to understand 1 to 5 star-ranking system. For the energy benchmark, it is
based on the ratio of actual kBtu per square foot compared to the benchmark kBtu per square foot model. A rating
higher than 2 1/2 stars means the building is performing better than expected. A rating less than 2 1/2 stars
indicates greater potential for savings.
Benchmarking
B3 Benchmarking Comparison
Be
n
c
h
m
a
r
k
i
n
g
R
a
t
i
n
g
0
1
3
2
4
5
0 4 12 20 24 32 40 44 52 56 64 68 76 80 88 92 100
Peer Rating
8 16 28 36 48 60 72 84 96
46
Fire Station 388 89City of Ames Energy Audit City of Ames Energy AuditFire Station 3
Methodology
The energy use of the building and energy efficiency measures were analyzed using a benchmarking approach that
separates the metered energy use into heating, cooling, and other end uses. A simplified energy model calculates
the savings of energy conservation measures.
Energy Use Characterization
The following graph shows the modeled energy use of the building broken down by end use. Heating energy use is
dominant making up 61% of the building’s energy use. Cooling energy makes up a small proportion of the energy
use due to only a portion of the building being cooled. The baseloads are made up of lighting, fans, water heating,
and equipment and is relatively constant throughout the year.
Energy Analysis
Electricity Natural GasEUI(kBtu/sq.ft./yr)
Energy Use Characterization by Energy End Use
Total 72.6
Baseload 25.4
• Interior Equipment
• Interior Lighting
• Domestic Hot Water
• Pumps
• Fans
Cooling 2.9
Heating 44.3
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1A: Office/Dorm Air-Source Heat Pump and Electric Resistance Heat
• Existing Condition: Natural gas-fired furnaces and air-cooled condensing units (air conditioners) in the office and
dorms.
• Proposed Energy Efficiency Measure: Air-source heat pumps paired with residential-style air handlers with
supplemental electric heating coils in the office and dorms.
• Recommendation for Implementation: Consider implementation when existing furnaces or condensing units
require replacement.
EEM 1B: Apparatus Bay Heat Pumps
• Existing Condition: Hydronic in-floor radiant heat provided by gas boilers and natural gas-fired hanging unit
heaters.
• Proposed Energy Efficiency Measure: Air-water heat pumps serve in-floor radiant heat with electric resistance
hanging unit heaters for back-up.
• Recommendation for Implementation: Consider implementation when existing equipment requires
replacement.
EEM 2A: Condensing Natural Gas-Fired Hot Water Heater
• Existing Condition: Standard efficiency natural gas-fired water heater serves building loads.
• Proposed Energy Efficiency Measure: Install a condensing (high-efficiency) natural gas-fired water to serve
building loads.
• Recommendation for Implementation: Consider installation when current water heater requires replacement.
EEM 2B: Hybrid Heat Pump Hot Water Heater
• Existing Condition: Standard efficiency natural gas-fired water heater serves building loads.
• Proposed Energy Efficiency Measure: Install a hybrid heat pump water heater to serve building loads.
• Recommendation for Implementation: Consider installation when current water heater requires replacement.
EEM 3A & 3B: Window Replacement
• Existing Condition: The double-glazed aluminum-framed windows are original to the building.
• Proposed Energy Efficiency Measure: Replace windows with a high-performing thermally-broken window
assembly that is better than current energy code minimums. EEM 5A evaluates the impact of a window
assembly with a U-factor of 0.29 and a Solar Heat Gain Coefficient (SHGC) of 0.32, while EEM 5B evaluates
the impact of a window assembly with a U-factor of 0.36 and a SHGC of 0.38.
• Recommendation for Implementation: Recommend implementing when windows reach their end of life, since
replacing windows will significantly impact building operations. The performance of EEM 5B is typical of a
high-performing double-pane window, while the performance of EEM 5A is achievable with either a higher-
performing double-pane window or a triple-pane window. Triple pane windows will offer additional acoustic
advantages, particularly for the dorm rooms. EEM 5A is recommended as a higher-performance option,
provided that the cost difference between the two options is minimal.
Energy Efficiency Measures
47
Fire Station 390 91City of Ames Energy Audit City of Ames Energy AuditFire Station 3
Energy Efficiency Measures
EEM 4 - Roof Insulation Increase
• Existing Condition: The existing roof is original to the building and is assumed to have an overall thermal
performance of R-15, which is typical of design and construction practices in the early 2000’s.
• Proposed Energy Efficiency Measure: Add additional insulation to increase the overall thermal performance to
R-30.
• Recommendation for Implementation: Recommend implementation when the roof membrane reaches its end
of life, in approximately 10 years. Based on initial assumptions, an additional 2” to 3” of polyiso insulation in the
roof assembly is expected to achieve R-30 performance. Existing insulation thickness and condition should
be further reviewed and confirmed prior to the roof upgrade to verify additional insulation levels to meet R-30
performance.
Estimated Costs for Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate Incremental Cost
Low High
1A Air-source heat pump and electric resis-
tance heat
Direct replacement of existing furnace
and condensing unit.
$30,000 $40,000 $8,000 $18,000
1B Apparatus Bay Heat Pumps Direct replacement of natural gas-fired furnaces and unit heaters.$20,000 $2,000 $21,000 $36,000
2A Condensing Natural Gas-Fired Hot Water
Heater
Direct replacement of standard efficiency
natural gas-fired water heater.
$3,000 $0 $2,000 $7,000
2B Hybrid Heat Pump Hot Water Heater Direct replacement of standard efficiency
natural gas-fired water heater.
$3,000 $400 $5,350 $6,100
3A Window Replacement: U-factor 0.29, SHGC 0.32 Energy Code-Compliant Window Re-placement $16,071 $0 $1,607 $6,910
3B Window Replacement:
U-factor 0.36, SHGC 0.38
Energy Code-Compliant Window Re-
placement
$16,071 $0 $0 $3,214
4 Roof Insulation Increase Replace roof membrane without adding
insulation
$18,792 $0 $21,074 $30,295
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved1
($/kgCO2e)
Simple
Average
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms Energy
Cost
CO2
Emissions
(kgCO2e)
1A Air-source heat pump and
electric resistance heat
HVAC
System
(32) (13,537) 2,972 $1,169 19,920 $0.027 -
$0.060
11.1 Implement at end of
system life
1B Apparatus Bay Heat Pumps HVAC
System
(6) (6,782) 1,085 $236 6,315 $0.222 -
$0.380
N/A
2A Condensing Natural Gas-
Fired Hot Water Heater
Plumbing
System
- - 74 $57 674 $0.297 -
$1.038
N/A Implement at end of
system life
2B Hybrid Heat Pump Hot Water Heater Plumbing System (1) (1,963) 398 $33 2,590 $0.207 - $0.236 N/A
3A Window Replacement:
U-factor 0.29, SHGC 0.32
Building
Envelope
2 1,006 792 $698 7,704 $0.007 -
$0.030
6.1 Implement at end of
system life
3B Window Replacement:
U-factor 0.36, SHGC 0.38
Building
Envelope
1 363 673 $558 6,294 $0 - $0.017 2.9
4 Roof Insulation Increase Building
Envelope
0 110 185 $155 1,738 $0.404 -
$0.581
N/A Implement at end of
system life
1 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to
have a life of 10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either
15 years for smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-
fired equipment.
Estimated Savings for EEM Bundles
Estimated energy savings from implementing all recommended measures are shown in the following charts. The first
chart shows the savings in annual EUI, the second chart shows the savings in annual energy cost, and the third chart
shows the savings in annual carbon emissions. The columns are described as follows:
• Existing +: Implement EEMs 2B, 3A and 4 to improve building envelope and domestic hot water systems.
• Air Source Heat Pump Office/Dorm: Implement EEM 1A by installing air-source heat pumps and electric
resistance heat to replace furnaces and condensing units.
• Air Source Heat Pump Office/Dorm +: Implement EEM 1A by installing air -source heat pumps with electric
resistance heat for apparatus bay plus EEMs 2B, 3A, and 4.
• Air Source Heat Pump Apparatus Bay: Implement EEM 1B by installing air-source heat pumps and electric
resistance heat to replace furnaces and unit heaters in apparatus bay.
• Air Source Heat Pump Apparatus Bay +: Implement EEM 1B by installing air-source heat pumps and electric
resistance heat in apparatus bay plus EEMs 2B, 3A, and 4.
• Air Source Heat Pump (all): Implement EEMs 1A and 1B by installing air-source heat pumps and electric
resistance heat for full building.
• Air Source Heat Pump (all)+: Implement EEMs 1A and 1B by installing air-source heat pumps and electric
resistance heat for full building plus EEMs 2B, 3A, and 4.
Energy Efficiency Measures
48
93City of Ames Energy AuditFire Station 392City of Ames Energy Audit
Energy Efficiency Measures
Predicted Annual EUI Savings
kB
T
U
/
f
t
2/y
r
Predicted Annual Energy Cost Savings
Predicted Annual Carbon Emissions Savings
kg
C
O
2e
Public Works and Fleet
49
Public Works and Fleet94 95City of Ames Energy Audit City of Ames Energy AuditPublic Works and Fleet
Facility Description
Building Contact Information
Building Name Public Works and Fleet
Address 2207 Edison Street
Ames, IA 50010
Building Owner City of Ames
Key Contact Corey Mellies, Fleet Services Director
Building Characteristics
General
Year of original construction: 1970
Building Climate Zone: 5A
Gross floor area: 34,115 sq.ft.
Total conditioned area: 34,115 sq.ft.
Total number of floors: 1
Conditioned floors above grade: 1
Conditioned floors below grade: 0
Use Type
Primary building use type: Maintenance Shop and Office
Secondary building use type: Storage/Warehouse
Major Renovations
1980 10,400 sq.ft. addition
1990 3,200 sq.ft. addition
2014-2016 Roof renovation
Operations
Typical weekly occupancy: Monday through Friday, 8:00 a.m. to 5:00 p.m.
Typical annual occupancy: 52 weeks/year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
The exterior walls are concrete masonry units with fill insulation. The window
to wall ratio is approximately 1%. The south-facing windows and glazed entry
door (which account for the majority of the fenestration area) were replaced
around 2024. The windows are double-glazed aluminum frame fixed
windows. The garage is equipped with insulated sectional overhead garage
doors that have two rows of IGUs to allow for views outdoors and some
daylight access in the service bays. There are also skylights with translucent
glazing and a wood frame in the 1977 addition, which account for about 1%
of the building’s total roof area.
The roof was renovated in between 2014 and 2016. As part of the
renovation, a new EPDM roof membrane was installed over 5” of new polyiso
insulation and the existing metal deck.
Lighting System
Lighting includes both LED and fluorescent fixtures. Most LED lamps are
replacements in fluorescent fixtures, though some LED high-bay fixtures
have been installed to replace fluorescent fixtures. There are remaining
fluorescent lamps in a number of areas. Lighting controls are typically
manual, line-voltage type. No occupancy/vacancy or dimming controls were
observed.
HVAC Systems
Several HVAC systems serve the City of Ames Public Works and Fleet
Building. Natural gas-fired furnaces with associated condensing units and
cooling coils serve office, common, and conference room areas. Natural
gas-fired unit heaters, waste oil heaters, and dedicated exhaust systems
serve maintenance and storage areas. The break room and office area is
served by a natural gas-fired unit heater. Dedicated source capture exhaust
is provided at locations throughout the maintenance garage. Some heat for
garage/shop areas is provided by a waste oil-burning heater.
Plumbing Systems
Normal domestic hot water is provided by an electric resistance, tank-type
hot water heater. A specialty high-temperature, high-pressure cleaning
system is provided in the maintenance garage for vehicle washing (Hotsy
unit).
East Elevation
Energy Recovery Ventilator
Conference Room Lighting
Snorkel Exhaust System + Lighting
Water Wash System
Waste Oil Heater
50
Public Works and Fleet96 97City of Ames Energy Audit City of Ames Energy AuditPublic Works and Fleet
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on May 22, 2025.
Observations
Building Envelope
• Several overhead garage doors have condensation inside the insulated
glazing unit. Recommend IGU replacement.
• Multiple exterior doors have visible rust. Rusting was noted as a frequent
issue in this building given the presence of salt in facility operations.
• Regularly occupied administrative areas are located in the center of
the building and do not have direct contact with the exterior walls.
Administration areas have little access to daylight.
• Multiple gaps are present around overhead garage doors. Recommend
improved weatherstripping to reduce infiltration.
• The exterior surface of the concrete masonry units is deteriorating in
several locations. Recommend monitoring and repair as needed.
• The skylights have accumulated dirt, resulting in reduced visible light
transmittance. General condition of the skylights also appears to be
poor. Recommend cleaning and further inspection; replace skylights if
needed upon further review.
Lighting Systems
• Mixture of lamps and fixture types throughout the facility – many
converted to LED, but there are a number of fluorescent lamps
remaining and all interior lighting is controlled manually.
HVAC Systems
• Some occupied areas may not be provided with adequate ventilation
(particularly breakroom/office area on first floor). Consideration should
be given to addressing this when improvements are made to the building.
• Long-term use of the waste-oil heater is not recommended due to likely
high rate of emissions and potential operational and safety issues. It is
likely appropriate to replace this equipment with either natural gas-fired
heaters or air-source heat pump equipment when feasible. This has not
been presented as an energy efficiency measure due to several factors
that complicate the analysis compared to use of other energy sources
for both cost and emissions.
Plumbing Systems
• Existing water heater is adequate for hand-washing and other normal
building usage, but does not have capacity to provide tempered water
to emergency fixtures. City does not anticipate need for emergency
shower in the near future for this facility.
Condensation Within IGU
Interior Office Admin Space
Visible Gap Under Garage Door
Skylight
Deteriorating CMU Surface
Electric Water Heater
Monthly Electric Usage
The monthly electrical consumption profile shows an increase in both the summer due to cooling and an increase in
the winter due to heating.
Monthly Natural Gas Usage
The monthly natural gas consumption profile shows a typical pattern of higher usage in the winter than in the
summer due to natural gas serving the heating loads. Natural gas consumption in the summer is due to heating hot
water.
Overview
Metered energy data for electricity and natural gas from December 2019 through December 2024 was collected
during the audit and is documented below. In addition to using metered electricity and natural gas, waste oil is
burned for heating in the vehicle areas. The quantity of waste oil burned is unknown; the estimated values for waste
oil shown in this section are an educated guess.
Utility Bill Analysis
70.4
kBtu/ft2/yr*
Energy Use
Annual Energy Use Intensity (EUI)
Based on measured energy use between
December 2023 and November 2024 for
electricity and natural gas, and an estimated
energy use for waste oil, the building has
an estimated energy use intensity of 70.4
kBtu/sq.ft./yr. About 24% of the building’s
annual energy use is attributed to electricity,
about 51% of the building's energy use is
attributed to natural gas, and about 25% of
the building’s annual energy use is attributed
to waste oil.
Monthly Natural Gas Use
Jun 2023-May 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Monthly Electric Use
Dec 2023-Nov 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Estimated Annual Energy Use Intensity
Dec 2023-Nov 2024
Electric
Natural Gas
Electric
6/23-6/24
Electric Baseline1/20-12/20
kW
h
Natural Gas
6/23-5/24
Natural Gas Baseline1/20-12/20
Th
e
r
m
s
Dec 2023 - Nov 2024
10,000
20,000
0
2,000
4,000
6,000
0
10
60
5,000
0 Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 2024
15,000
Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 2024
20
30
40
50
70
80
Waste Oil
*Quantity of waste oil burned is unknown. The estimated value for waste oil shown here is an educated guess.
51
Public Works and Fleet98 99City of Ames Energy Audit City of Ames Energy AuditPublic Works and Fleet
Energy Cost
Annual Energy Cost
Based on the measured energy use and utility bills between December 2023 and November 2024, the building’s
annual energy cost is $28,377. 63% of the building’s annual energy cost is attributed to electricity, while the
remaining 37% of the building’s annual energy cost is attributed to natural gas. Both electricity and natural gas
costs have remained consistent over the past few years.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use for electricity and natural gas between January 2023 and December 2023, as
well as estimated energy use for waste oil, the building’s estimated annual carbon emissions is 235.6 mt-CO2e/yr.
About 39% of the building’s annual carbon emissions is attributed to electricity, about 31% is attributed to natural
gas, and about 30% is attributed to waste oil.
Utility Bill Analysis
$28,377/yr
Annual Energy Cost Comparison
2021-2023
Estimated Annual Carbon Emissions
2023
Annual Energy Costs
Dec 2023-Nov 2024
Electric
Natural Gas
Electric
Natural Gas
Electric
Natural Gas
Me
t
r
i
c
T
o
n
s
C
O
2e
Co
s
t
2023
0
50
150
250
2021 2022 2023
0
$10,000
$20,000
$30,000
100
$40,000
Waste Oil
200
The building ranks in the 20 percentile to 126 other peer vehicle repair services buildings in the B3 Benchmarking
tool (80% of vehicle repair services buildings have better performance). This indicates that there are good
opportunities for reducing the building’s energy use.
The B3 Benchmark Rating is an easy to understand 1 to 5 star-ranking system. For the energy benchmark, it is
based on the ratio of actual kBtu per square foot compared to the benchmark kBtu per square foot model. A rating
higher than 2 1/2 stars means the building is performing better than expected. A rating less than 2 1/2 stars
indicates greater potential for savings. Given the relatively poor performance of this facility compared to others,
it appears that the 5 star rating for this facility type may be misleading. As noted above, this facility has good
opportunity for reducing building energy use.
Benchmarking
B3 Benchmarking Comparison
Be
n
c
h
m
a
r
k
i
n
g
R
a
t
i
n
g
0
1
3
2
4
5
0 4 12 20 24 32 40 44 52 56 64 68 76 80 88 92 100
Peer Rating
8 16 28 36 48 60 72 84 96
52
Public Works and Fleet100 101City of Ames Energy Audit City of Ames Energy AuditPublic Works and Fleet
Methodology
The energy use of the building and energy efficiency measures were analyzed using a benchmarking approach that
separates the metered energy use into heating, cooling, and other end uses. A simplified energy model calculates
the savings of energy conservation measures.
Energy Use Characterization
The following graph shows the modeled energy use of the building broken down by end use. Heating energy is the
dominant energy use in the building, making up 72% of the energy use. Cooling energy is small compared to other
loads due to only a portion of the building being cooled. Baseload energy uses, including lighting, water heating,
equipment and fans make up 25% of the energy use and remain relatively constant year-round.
Energy Analysis
Electricity Natural GasEUI(kBtu/sq.ft./yr)
Energy Use Characterization by Energy End Use
Total 53.2
Baseload 13.2
• Interior Equipment
• Interior Lighting
• Domestic Hot Water
• Pumps
• Fans
Cooling 1.5
Heating 38.5*
*Does not include energy use of waste oil.
Oil
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1 - Replace Condensing Units with Air-Source Heat Pumps
• Existing Condition: Natural gas-fired furnaces with air-cooled condensing units.
• Proposed Energy Efficiency Measure: Air-source heat pumps paired with air handling units with supplemental
electric heating coil – may consider natural gas-fired furnace depending on replacement timing and expected
emissions rate from electric utility.
• Recommendation for Implementation: Implement when equipment replacement is required.
EEM 2 - Heat Pump Water Heater
• Existing Condition: Electric resistance tank-type water heater.
• Proposed Energy Efficiency Measure: Heat pump water heater.
• Recommendation for Implementation: Consider when existing water heater requires replacement (likely
requires smaller circuit).
EEM 3 - LED Lighting Upgrades
• Existing Condition: Some fixtures remain fluorescent.
• Proposed Energy Efficiency Measure: Convert or replace all fixtures to LED.
• Recommendation for Implementation: As soon as feasible. It should be noted that the simple payback
presented in the Estimated Savings for EEMs table is calculated based on energy cost savings and first cost
only, and does not account for maintenance costs associated with replacing lamps in existing fluorescent
fixtures. Accounting for these maintenance costs would improve the payback associated with this strategy,
but to maintain consistency across the simple payback calculations presented in the Estimated Savings for
EEMs table, the life cycle cost savings associated with lamp replacement were not included.
EEM 4 - Lighting Occupancy/Vacancy Controls
• Existing Condition: Manual lighting controls throughout the building.
• Proposed Energy Efficiency Measure: Add automatic lighting controls where suitable for safety.
• Recommendation for Implementation: As soon as feasible.
Energy Efficiency Measures
53
Public Works and Fleet102 103City of Ames Energy Audit City of Ames Energy AuditPublic Works and Fleet
Estimated Costs for Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate Incremental Cost
Low High
1 Replace Condensing Units with Air-Source
Heat Pumps
Direct replacement of existing furnace
and condensing unit
$45,000 $60,000 $12,000 $27,000
2 Heat Pump Water Heater Direct replacement of existing electric
water heater
$3,000 $400 $3,100 $3,850
3 LED Lighting Upgrades Do nothing $0 $0 $34,115 $51,173
4 Lighting Occupancy/Vacancy Controls Do nothing $0 $0 $12,793 $17,058
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved2
($/kgCO2e)
Simple
Average
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms1 Energy
Cost
CO2
Emissions
(kgCO2e)
1 Replace Condensing Units
with Air-Source Heat Pumps
HVAC
System
(107,817) 18,156 $(545) 124,999 $0.006 -
$0.014
N/A Implement when
equipment replace-
ment is required
2 Heat Pump Water Heater Plumbing
System
3 5,477 - $926 2,849 $0.109 -
$0.135
3.8 Implement when
equipment replace-
ment is required
3 LED Lighting Upgrades Lighting 2 5,806 (110) $466 2,023 $0.843 -
$1.265
N/A Implement as soon as
feasible
4 Lighting Occupancy/Vacancy
Controls
Lighting 4 15,758 (335) $1,092 5,159 $0.124 -
$0.165
13.7 Implement along with
other lighting or build-
ing improvements
1 Estimated annual therm savings includes natural gas and waste oil.
2 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to
have a life of 10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either
15 years for smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-
fired equipment.
Estimated Savings for EEM Bundles
Estimated energy savings from implementing all recommended measures are shown in the following charts. The first
chart shows the savings in annual EUI, the second chart shows the savings in annual energy cost, and the third chart
shows the savings in annual carbon emissions. The columns are described as follows:
• Existing +: Implement EEMs 2-4 to improve lighting and domestic hot water systems.
• Air Source Heat Pump: Implement EEM 1 by replacing the existing HVAC system with air-source heat pumps.
• Air Source Heat Pump +: Implement EEM 1 by replacing the existing HVAC system with air-source heat pumps
plus implement EEMs 2-4.
Energy Efficiency Measures Energy Efficiency Measures
Predicted Annual EUI Savings
kB
T
U
/
f
t
2/y
r
Predicted Annual Energy Cost Savings
Predicted Annual Carbon Emissions Savings
kg
C
O
2e
54
105City of Ames Energy Audit
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Electric Distribution
55
Electric Distribution106 107City of Ames Energy Audit City of Ames Energy AuditElectric Distribution
Facility Description
Building Contact Information
Building Name Electric Distribution
Address 2220 Edison Street
Ames, IA 50010
Building Owner City of Ames
Key Contact Corey Mellies, Fleet Services Director
Building Characteristics
General
Year of original construction: 1980
Building Climate Zone: 5A
Gross floor area: 27,322 sq.ft.
Total conditioned area: 27,322 sq.ft. heated, approximately 5,000 sq.ft. cooled
Total number of floors: 1
Conditioned floors above grade: 1
Conditioned floors below grade: 0
Use Type
Primary building use type: Warehouse and Office
Secondary building use type: N/A
Major Renovations
2016 Roof renovation
Operations
Typical weekly occupancy: Monday through Friday, 8:00 a.m. to 5:00 p.m.
Typical annual occupancy: 52 weeks/year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
The typical exterior wall is an insulated precast assembly with 2” of rigid
insulation sandwiched between 3” of precast concrete on both sides. At the
office areas, a hollow metal insulated infill wall panel is located below the
windows with 2” of rigid insulation and ½” M.D.O. plywood.
The window to wall ratio is approximately 4%, with the windows located
in the office administration area of the building. These fixed windows are
original to the 1978 building, with a tinted double-glazed steel-frame
assembly. The main building entrance has a storefront system with a glazed
entry door that enters into a vestibule. The garage is equipped with insulated
sectional overhead garage doors that have small glazed openings.
The roof was renovated in 2016. As part of the renovation, a new white TPO
roof membrane, over 5” of rigid polyiso insulation and the existing metal
deck.
Lighting System
Lighting throughout the building is typically LED, with a mixture of fixture
types. Interior lighting controls are manual, with no occupancy/vacancy
or daylight dimming controls. Exterior lighting appears to have photocell
control.
HVAC Systems
Air-source heat pumps paired with air handling units having supplemental
electric heat serve the front office area, break room, and restrooms/locker
rooms. A split system provides cooling to the computer room space, with
the condensing unit located in the truck bay area. Bay areas have partially
functional in-floor electric resistance heating along with hanging electric
heaters. Dedicated exhaust fans serve restrooms and similar spaces. Bay
areas and parts warehouse have exhaust fans and gravity intakes.
Plumbing Systems
Domestic hot water is produced by an electric hot water heater and the
system is equipped with a domestic hot water recirculation pump.
South Elevation
Interior Lighting and Exhaust
Horizontal AHU with Electric Coil
Roof
Electric Heaters
Typical window and infill wall panel
56
Electric Distribution108 109City of Ames Energy Audit City of Ames Energy AuditElectric Distribution
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on May 22, 2025.
Observations
Building Envelope
• Weatherstripping on bottom of an overhead garage doors requires repair.
• Several overhead garage doors have condensation inside the insulated
glazing unit due to broken seals.
• The condition of the windows and infill wall panels in the office area is
poor and provides little thermal insulation. Staff reported using electric
heaters in offices during the winter to improve thermal comfort.
Lighting Systems
• LED lighting systems are modern, but updated controls would be
appropriate for building systems.
HVAC Systems
• Appears ventilation may not be adequate for normally occupied areas
served by air handling units/air-source heat pumps.
Plumbing Systems
• Electric water heater is likely adequate for building needs/usage.
Other
• Mold was present on acoustic ceiling tiles. The mold appears to be due
to condensation from ductwork above the ceiling tiles. Recommend
further investigation into this issue and insulating ductwork.
Garage Door with Gap at Bottom
Condensation within Garage Door IGU
Window and Infill Panel
Mold and Water Damage on Ceiling
Monthly Electric Usage
The monthly electricity consumption shows a pattern of higher usage in the winter due to electricity serving
heating loads.
Energy Cost
Annual Energy Cost
Based on the measured energy use and utility bills between January 2021 and December 2023 the annual energy
cost has varied between about $32,000 and $38,000.
Overview
Metered energy data from November 2019 through December 2024 was collected during the audit and is
documented below. The building is all electric, and much of the building is heated but not cooled.
Utility Bill Analysis
35.4
kBtu/ft2/yr
Energy Use
Annual Energy Use Intensity (EUI)
Based on measured energy use between
December 2023 and November 2024, the
building has an energy use intensity of 35.4
kBtu/sq.ft./yr. 100% of the building’s annual
energy use is attributed to electricity.
Monthly Electric Use
Dec 2023-Nov 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Annual Energy Use Intensity
Dec 2023-Nov 2024
Electric
Electric12/23-11/24
Electric Baseline1/20-12/20
kW
h
Jun 2023 - May 2024
40,000
60,000
0
20
40
20,000
0 Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 2024
$35,046/yr
Annual Energy Cost Comparison
2021-2023
Annual Energy Costs
Oct 2021 - Sep 2022
Electric
Electric
Co
s
t
2021 2022 2023
0
$10,000
$30,000
$40,000
$20,000
57
Electric Distribution110 111City of Ames Energy Audit City of Ames Energy AuditElectric Distribution
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use from January 2023 to December 2023, the building’s annual carbon emissions
are 174 mt CO2e/yr. 100% of the building’s annual CO2e emissions are attributed to electricity.
Utility Bill Analysis
Annual Carbon Emissions
2023
Electric
Me
t
r
i
c
T
o
n
s
C
O
2e
2023
0
50
150
200
100
The building ranks in the 62nd percentile to 563 other peer warehouse buildings in the B3 Benchmarking tool
(38% of warehouse buildings have better performance). This indicates that the building is a good candidate for
energy reduction strategies through retrofits.
The B3 Benchmark Rating is an easy to understand 1 to 5 star-ranking system. For the energy benchmark, it is
based on the ratio of actual kBtu per square foot compared to the benchmark kBtu per square foot model. A rating
higher than 2 1/2 stars means the building is performing better than expected. A rating less than 2 1/2 stars
indicates greater potential for savings.
Benchmarking
B3 Benchmarking Comparison
Be
n
c
h
m
a
r
k
i
n
g
R
a
t
i
n
g
0
1
3
2
4
5
0 4 12 20 24 32 40 44 52 56 64 68 76 80 88 92 100
Peer Rating
8 16 28 36 48 60 72 84 96
58
Electric Distribution112 113City of Ames Energy Audit City of Ames Energy AuditElectric Distribution
Methodology
The energy use of the building and energy efficiency measures were analyzed using a benchmarking approach that
separates the metered energy use into heating, cooling, and other end uses. A simplified energy model calculates
the savings of energy conservation measures.
Energy Use Characterization
The following graph shows the benchmarked energy use of the building broken down by end use. Approximately
60% of the energy use in the building is for heating, 3% is for cooling, and 37% is for other uses including lighting,
equipment, and water heating. The cooling energy is small for the building due to a significant proportion of the
building is not cooled.
Energy Analysis
Electricity Natural GasEUI(kBtu/sq.ft./yr)
Energy Use Characterization by Energy End Use
Total 35.4
Baseload 13.2
• Interior Equipment
• Interior Lighting
• Domestic Hot Water
• Pumps
• Fans
Cooling 1.1
Heating 21.1
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1: Air Source Heat Pumps for Garage and Shop Areas
• Existing Condition: Electric unit heaters serve garage and shop areas.
• Proposed Energy Efficiency Measure: Air-source heat pumps with supplemental electric heat serve garage
and shop areas.
• Recommendation for Implementation: Consider when unit heaters require replacement.
EEM 2: Lighting Occupancy/Vacancy Controls
• Existing Condition: Manual lighting controls throughout interior of building.
• Proposed Energy Efficiency Measure: Add occupancy/vacancy sensors for appropriate areas throughout the
building.
• Recommendation for Implementation: Implement as soon as feasible.
EEM 3: Heat Pump Water Heater
• Existing Condition: Electric resistance tank-type water heater.
• Proposed Energy Efficiency Measure: Heat pump water heater.
• Recommendation for Implementation: Consider when replacement is required.
EEM 4A & 4B: Window Replacement
• Existing Condition: The existing windows are original to the building and have reached the end of their useful end
of life. The steel framed double-glazed windows do not have thermal breaks and contribute to thermal discomfort.
• Proposed Energy Efficiency Measure: Replace windows with a high-performing thermally-broken window
assembly that is better than current energy code minimums. EEM 4A evaluates the impact of a window
assembly with a U-factor of 0.29 and a Solar Heat Gain Coefficient (SHGC) of 0.32, while EEM 4B evaluates
the impact of a window assembly with a U-factor of 0.36 and a SHGC of 0.38. EEM 4A is recommended as a
higher-performance option, provided that the cost difference between the two options is minimal.
• Recommendation for Implementation: Recommend replacing windows as soon as possible. While replacing
the windows, also replace the infill wall panels below the windows. The existing infill wall panels are in poor
condition and not energy efficient, as the steel frame contributes to high levels of thermal bridging and thermal
discomfort. Recommend replacing the existing infill wall panels with a metal stud wall with continuous insulation
to achieve higher levels of thermal performance, up to R-20.
EEM 5: Overhead Sectional Door Replacement
• Existing Condition: The existing overhead sectional doors in the service bay are showing signs of age. The
glazed openings in the door are not providing useful levels of daylight due to the small opening size, and multiple
insulated glazing units have condensation in between the two panes of glass.
• Proposed Energy Efficiency Measure: Replace the existing doors with ones that have a higher R-value of R-15.
• Recommendation for Implementation: Recommend replacing the overhead sectional doors with a higher
performance option when the overhead doors reach the end of their useful life. When installing a higher
performance door, pay special attention to detailing and around all sides of the door to limit infiltration.
Additionally, consider introducing larger areas of glazing in the doors than the current condition, to allow for
more views and daylight in the service bay. Additional glazing will reduce the overall R-value of the door, so the
glazed area vs. performance trade-offs should be further considered.
Energy Efficiency Measures
59
Electric Distribution114 115City of Ames Energy Audit City of Ames Energy AuditElectric Distribution
Estimated Costs for Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate Incremental Cost
Low High
1 Air Source Heat Pumps for Garage and
Shop Areas
Replace with electric resistance unit
heaters
$60,000 $4,000 $16,000 $36,000
2 Lighting Occupancy/Vacancy Controls Do nothing $0 $0 $10,245 $13,661
3 Heat Pump Water Heater Direct replacement of existing electric
water heater
$3,000 $400 $3,100 $3,850
4A Window Replacement:
U-factor 0.29, SHGC 0.32
Energy Code-Compliant Window Re-
placement
$23,300 $0 $2,328 $10,009
4B Window Replacement:
U-factor 0.36, SHGC 0.38
Energy Code-Compliant Window Re-
placement
$23,300 $0 $0 $4,655
5 Overhead Sectional Door Replacement Replacement with standard overhead
insulated sectional door
$88,958 $0 $8,899 $11,865
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved1
($/kgCO2e)
Simple
Average
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms Energy
Cost
CO2
Emissions
(kgCO2e)
1 Air Source Heat Pumps for
Garage and Shop Areas
HVAC
System
1 84,028 - $8,695 43,711 $0.024 -
$0.055
3.0 Implement when
equipment replace-
ment is required
2 Lighting Occupancy/Vacancy
Controls
Lighting (1) 5,501 - $419 2,862 $0.179 -
$0.239
N/A Implement along
with other building
improvements
3 Heat Pump Water Heater Lighting 0 3,181 - $394 1,655 $0.187 -
$0.233
8.8 Implement when
equipment replace-
ment is required
4A Window Replacement:
U-factor 0.29, SHGC 0.32
Building
Envelope
19 13,844 - $1,539 7,202 $0.011 -
$0.046
4.0 Implement as soon as
feasible
4B Window Replacement:
U-factor 0.36, SHGC 0.38
Building
Envelope
14 8,998 - $1,127 4,681 $0 - $0.033 2.1
5 Overhead Sectional Door
Replacement
Building
Envelope
10 12,252 - $1,349 6,373 $0.047 -
$0.062
7.7 Implement at end of
system life
1 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to
have a life of 10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either
15 years for smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-
fired equipment.
Energy Efficiency Measures
Estimated Savings for EEM Bundles
Estimated energy savings from implementing all recommended measures are shown in the following charts. The first
chart shows the savings in annual EUI, the second chart shows the savings in annual energy cost, and the third chart
shows the savings in annual carbon emissions. The columns are described as follows:
• Existing +: Implement EEMs 2, 3 ,4A, and 5 to improve lighting and building envelope systems.
• Air Source Heat Pump: Implement EEM 1 to improve the mechanical systems.
• Air Source Heat Pump +: Implement EEMs 1-3, 4A, and 5 to improve the mechanical, lighting and building
envelope systems.
Energy Efficiency Measures
Predicted Annual EUI Savings
kB
T
U
/
f
t
2/y
r
Predicted Annual Energy Cost Savings
60
117City of Ames Energy AuditElectric Distribution116City of Ames Energy Audit
Predicted Annual Carbon Emissions Savings
kg
C
O
2e
Energy Efficiency Measures
Electric Administration
61
Electric Administration118 119City of Ames Energy Audit City of Ames Energy AuditElectric Administration
Facility Description
Building Contact Information
Building Name Electric Administration
Address 502 Carroll Avenue
Ames, IA 50010
Building Owner City of Ames
Key Contact Robb Chapman, Utility Engineer
Building Characteristics
General
Year of original construction: 1979
Building Climate Zone: 5A
Gross floor area: 4,241 sq.ft.
Total conditioned area: 4,241 sq.ft.
Total number of floors: 1
Conditioned floors above grade: 1
Conditioned floors below grade: 0
Use Type
Primary building use type: Office
Secondary building use type: N/A
Major Renovations
2009 Building updates
2016 Roof renovation
Operations
Typical weekly occupancy: Monday through Friday, 8:00 a.m. to 5:00 p.m.
Typical annual occupancy: 52 weeks per year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
The exterior of the building features wood siding and brick veneer. The walls
with wood siding utilize wood studs spaced 24” on center with batt insulation
between the studs. There are two types of walls with brick veneer: one type
that utilized wood studs spaced 24” on center with batt insulation between
the studs, and another that utilizes 6” concrete masonry units with 1.5” rigid
insulation. All wall types have gypsum board as the interior finish.
The window to wall ratio is approximately 15%. The windows are original to
the building and most of them are double-glazed aluminum-framed with an
operable circular vent. A couple of windows and exterior glazed doors are
single-glazed with aluminum frames.
The roof was renovated in 2016. The renovation includes a new tan TPO roof
membrane and 5” of rigid polyiso insulation over the existing metal deck.
Lighting System
The building is equipped with a mixture of LED and fluorescent light fixtures.
The lighting controls are all manual, with no occupancy/vacancy controls or
dimming capabilities.
HVAC Systems
HVAC systems serving this facility primarily consist of air-source heat pumps
paired with residential-style air handling units including electric resistance
heating coils. Units are equipped with zoning dampers for different zones
within spaces served by a single unit. Outdoor air is introduced to the air
handling units through direct ducted intakes to the exterior of the building.
Small, dedicated exhaust fans serve restrooms and custodial space.
Plumbing Systems
A small-volume tank-type electric resistance water heater provides domestic
hot water to the building.
East Elevation
Air Handler with Electric Coil
Air Source Heat Pumps
Corridor Lighting
Electric Water Heater
62
Electric Administration120 121City of Ames Energy Audit City of Ames Energy AuditElectric Administration
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on June 3, 2025.
Observations
Building Envelope
• Building staff have installed make-shift opaque panels out of rigid
insulation in several offices to improve thermal comfort. The insulation
has been placed behind the bottom lites of the windows.
• A couple of windows are doors are single-glazed, contributing to heat
loss and thermal discomfort.
• Several areas of brick require repointing.
• Condensation is present inside a window IGU. Recommend replacement.
Lighting Systems
• Opportunity for electrical savings and demonstration of appropriate
technology by incorporating modern lighting controls in building.
HVAC Systems
• Outdoor air intakes appear unlikely to provide code-required ventilation
to all occupied spaces.
• Concerns about comfort related to zoning/system operation.
Plumbing Systems
• Small electric hot water heater is adequate for hand-washing and similar
usage. This unit would not be adequate for showering or higher-use
fixtures.
Added Rigid Insulation at Windows
Brick Repointing Needed
Typical Zoning Bypass
HVAC Zoning Controls
Incandescent Lamp
Monthly Electric Usage
The monthly electricity consumption shows a pattern of higher usage in the winter due to electricity serving the
heating loads.
Energy Cost
Energy cost data was not available.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use from January 2023 to December 2023, the building’s annual carbon emissions
are 24.9 mt CO2e/yr. 100% of the building’s annual CO2e emissions are attributed to electricity.
Overview
Metered energy data from October 2019 through December 2024 was collected during the audit and is
documented below. The building is all electric with relatively efficient systems.
Utility Bill Analysis
35.7
kBtu/ft2/yr
Energy Use
Annual Energy Use Intensity (EUI)
Based on measured energy use
between December 2023 and
November 2024, the building has an
energy use intensity of 35.7 kBtu/sq.ft./
yr. 100% of the building’s annual energy
use is attributed to electricity.
Monthly Electric Use
Dec 2023-Nov 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Annual Energy Use Intensity
Dec 2023-Nov 2024
Electric
Electric
12/23-11/24
Electric Baseline1/20-12/20
kW
h
Dec 2023 - Nov 2024
5,000
10,000
0
20
40
0
Annual Carbon Emissions
2023
Electric
Me
t
r
i
c
T
o
n
s
C
O
2e
2023
0
10
20
30
Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 2024
63
Electric Administration122 123City of Ames Energy Audit City of Ames Energy AuditElectric Administration
The building ranks in the 73rd Percentile to 3,099 other peer Office buildings in the B3 Benchmarking tool (27%
of office buildings have better performance). This indicates that the building is a decent performer, and there are
opportunities for moderate energy reduction savings.
The B3 Benchmark Rating is an easy to understand 1 to 5 star-ranking system. For the energy benchmark, it is
based on the ratio of actual kBtu per square foot compared to the benchmark kBtu per square foot model. A rating
higher than 2 1/2 stars means the building is performing better than expected. A rating less than 2 1/2 stars
indicates greater potential for savings.
Benchmarking
B3 Benchmarking Comparison
Be
n
c
h
m
a
r
k
i
n
g
R
a
t
i
n
g
0
1
3
2
4
5
0 4 12 20 24 32 40 44 52 56 64 68 76 80 88 92 100
Peer Rating
8 16 28 36 48 60 72 84 96
Methodology
The energy use of the building and energy efficiency measures was analyzed using a benchmarking approach that
separates the metered energy use into heating, cooling, and other end uses. A simplified energy model calculates
the savings of energy conservation measures.
Energy Use Characterization
The following graph shows the benchmarked energy use of the building broken down by end use. Approximately
46% of the energy use in the building is for heating, 8% is for cooling, and 46% is for other uses including lighting,
equipment, and water heating.
Energy Analysis
Electricity Natural GasEUI(kBtu/sq.ft./yr)
Energy Use Characterization by Energy End Use
Total 35.7
Baseload 16.6
• Interior Equipment
• Interior Lighting
• Domestic Hot Water
• Pumps
• Fans
Cooling 2.7
Heating 16.4
64
Electric Administration124 125City of Ames Energy Audit City of Ames Energy AuditElectric Administration
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1 - Energy Recovery Ventilator
• Existing Condition: Outdoor air is introduced directly into return air of each air handling unit.
• Proposed Energy Efficiency Measure: Add energy recovery ventilator to provide continuous outdoor and
exhaust air while limiting energy consumption.
• Recommendation for Implementation: Depending on plans for building, wait if major improvements are planned
– if not, implement as soon as feasible.
EEM 2 - Replace Fluorescent Lighting
• Existing Condition: A portion of remaining lighting is fluorescent.
• Proposed Energy Efficiency Measure: Replace remaining fluorescent fixtures with LED fixtures.
• Recommendation for Implementation: Unless changes are planned for the building soon, replace fluorescent
fixtures as soon as feasible. It should be noted that the simple payback presented in the Estimated Savings
for EEMs table is calculated based on energy cost savings and first cost only, and does not account for
maintenance costs associated with replacing lamps in existing fluorescent fixtures. Accounting for these
maintenance costs would improve the payback associated with this strategy, but to maintain consistency
across the simple payback calculations presented in the Estimated Savings for EEMs table, the life cycle cost
savings associated with lamp replacement were not included.
EEM 3 - Lighting Occupancy and Vacancy Sensor Controls
• Existing Condition: Building does not have any automatic lighting controls.
• Proposed Energy Efficiency Measure: Add occupancy- or vacancy-based lighting controls to occupied spaces
wherever appropriate or required by code.
• Recommendation for Implementation: Consider implementation schedule to limit impact to building, but will
have benefit as soon as it is implemented (may depend on implemented technology for lighting control).
EEM 4A & 4B - Window Replacement
• Existing Condition: The double-glazed and single-glazed aluminum-framed windows are original to the building.
• Proposed Energy Efficiency Measure: Replace windows with a high-performing thermally-broken window
assembly that is better than current energy code minimums. EEM 4A evaluates the impact of a window
assembly with a U-factor of 0.29 and a Solar Heat Gain Coefficient (SHGC) of 0.32, while EEM 4B evaluates
the impact of a window assembly with a U-factor of 0.36 and a SHGC of 0.38.
• Recommendation for Implementation: Recommend implementing as soon as feasible. EEM 4A is
recommended as a higher-performance option, provided that the cost difference between the two options is
minimal. When replacing windows, also consider an option for insulated spandrel panels in the lower section of
the rough opening to further improve performance and thermal comfort.
Energy Efficiency Measures
Estimated Costs for Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate Incremental Cost
Low High
1 Energy Recovery Ventilator Do nothing $0 $0 $5,000 $10,000
2 LED Lighting Retrofit Remaining Fixtures Do nothing $0 $0 $1,000 $3,000
3 Lighting Occupancy and Vacancy Sensor
Controls
Do nothing $0 $0 $6,362 $8,482
4A Window Replacement:
U-factor 0.29, SHGC 0.32
Energy Code-Compliant Window
Replacement
$28,956 $0 $2,896 $12,451
4B Window Replacement:
U-factor 0.36, SHGC 0.38
Energy Code-Compliant Window
Replacement
$28,956 $0 $0 $5,791
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved1
($/kgCO2e)
Average
Simple
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms Energy
Cost
CO2
Emissions
(kgCO2e)
1 Energy Recovery Ventilator HVAC
System
3 676 - $126 351 $0.711 -
$1.422
N/A Implement as soon as
feasible
2 LED Lighting Retrofit Remaining Fixtures Lighting 0 1,282 - $113 667 $0.075 - $0.225 17.7 Implement as soon as feasible
3 Lighting Occupancy and
Vacancy Sensor Controls
Lighting - 2,458 - $188 1,279 $0.249 -
$0.332
N/A Implement with light-
ing fixture replace-
ments
4A Window Replacement:
U-factor 0.29, SHGC 0.32
Building
Envelope
9 7,336 - $919 3,816 $0.025 -
$0.060
8.3 Implement as soon as
feasible
4B Window Replacement: U-factor 0.36, SHGC 0.38 Building Envelope 8 6,177 - $749 3,213 $0 - $0.711 3.9
1 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to
have a life of 10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either
15 years for smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-
fired equipment.
Energy Efficiency Measures
65
Electric Administration126 127City of Ames Energy Audit City of Ames Energy AuditElectric Administration
Estimated Savings for EEM Bundles
Estimated energy savings from implementing all recommended measures are shown in the following charts. The first
chart shows the savings in annual EUI, the second chart shows the savings in annual energy cost, and the third chart
shows the savings in annual carbon emissions. The columns are described as follows:
• Existing +: implement EEMs 1-3 and 4A to improve the mechanical, lighting, and building envelope systems.
Energy Efficiency Measures
Predicted Annual EUI Savings
kB
T
U
/
f
t
2/y
r
Predicted Annual Energy Cost Savings
Predicted Annual Carbon Emissions Savings
kg
C
O
2e
Energy Efficiency Measures
66
129City of Ames Energy Audit
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Homewood Golf Course Clubhouse
67
Homewood Golf Course Clubhouse130 131City of Ames Energy Audit City of Ames Energy AuditHomewood Golf Course Clubhouse
Facility Description
Building Contact Information
Building Name Homewood Golf Course Clubhouse
Address 401 E 20th Street
Ames, IA 50010
Building Owner City of Ames
Key Contact Nate Pietz, Recreation Manager
Building Characteristics
General
Year of original construction: 2020
Building Climate Zone: 5A
Gross floor area: 5,106 sq.ft.
Total conditioned area: 3,263 sq.ft. heated and cooled (main level)
1,843 sq.ft. heated only (basement level)
Total number of floors: 2
Conditioned floors above grade: 1
Conditioned floors below grade: 1
Use Type
Primary building use type: Park/Recreation
Secondary building use type: Warehouse
Major Renovations
N/A
Operations
Typical weekly occupancy: Late Spring to Early Fall, Sunday through Saturday, 7:00 a.m to 7:00 p.m.
Typical annual occupancy: Approximately 28 to 30 weeks/year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
There are three primary types of above-grade exterior walls on the main
floor. All three wall types have similar levels of thermal performance with
2x6 metal studs at 16” on center (o.c.) with batt insulation between the
studs, as well as a vapor barrier and 5/₈” gypsum board. The exterior cladding
varies among the three wall types: one wall type uses cedar siding, another
wall type uses vinyl siding, and a third wall type uses a stone veneer with 1/2”
cement board.
The basement level uses reinforced concrete foundation walls with 1/2”
gypsum board on 2” of rigid insulation inboard of the foundation wall.
Outboard of the foundation wall on the west, south, and portion of the east
facade, there is stone veneer with ¹/₂” cement board, sheathing, and 2x3
furring at 16” o.c. with rigid insulation. Outboard of the foundation wall on the
north and majority of the east facade, there is vinyl siding, OSB sheathing,
and 2x3 furring at 16” o.c. with 1-1/2” rigid insulation. The basement
floor includes a 4” reinforced concrete floor slab over a vapor barrier and
compacted granular fill.
The window to wall ratio is approximately 24% and the windows are original
to the building. The windows are aluminum storefront systems with double-
pane insulated glazing units. Main building entrances include glazed entry
doors that enter into vestibules, and the garage is equipped with an insulated
sectional overhead garage door.
The roof system is comprised of an 8-¹/₄” structural insulated panel (SIP) with
metal shingles on the exterior and a wood shiplap ceiling on the interior.
Lighting System
Lighting systems are LED throughout the building. All areas appear to be
equipped with appropriate lighting controls to meet code requirements.
HVAC Systems
The HVAC system for the upper floor of the building generally consists of
ground-coupled (geothermal) water-source heat pumps. Local exhaust fans
serve a few spaces, and outdoor air is introduced directly to the return of the
heat pumps.
The lower floor of the building is equipped with a natural gas-fired unit heater,
with heating only.
Plumbing Systems
Domestic hot water is generated by a high-efficiency natural gas-fired tank-
type water heater.
Boiler and Water Heater
Gas-Fired Unit Heater
Ground Source Loop Pumps
Interior Lighting
Water-Source Heat Pumps
South Elevation
68
Homewood Golf Course Clubhouse132 133City of Ames Energy Audit City of Ames Energy AuditHomewood Golf Course Clubhouse
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on March 14, 2025.
Observations
Building Envelope
• The exterior walls on the main floor were not designed with continuous
insulation. Despite this omission, issues with thermal comfort were not
noted by building occupants.
• Weather seals at the bottoms of the doors are compromised and lead to
increased infiltration. Recommend installing door sweep.
• Areas of caulk around windows are in need of repair.
Lighting Systems
• Modern system uses appropriate controls.
HVAC Systems
• There may be issues with getting adequate outdoor air flow to the
building as there is less exhaust than there is required outdoor air and
outdoor air is not introduced with positive pressure.
• There may be benefit to adding an energy recovery ventilator to the
building.
• Appears that exhaust may be appropriate from concessions area.
caption
Caulk around Window
Door without Door Sweep
Monthly Electric Usage
The monthly electricity consumption pattern shows a peak in the summer months due to cooling and electric
charging loads. There is another slight peak in the winter months due to heating loads from heat pumps.
Monthly Natural Gas Usage
The monthly natural gas consumption shows a peak in the winter months which can be attributed to heating loads
in the lower level and backup heating supply in the main level.
Overview
Metered energy data from May 2021 through December 2024 was collected during the audit and is documented
below. Electricity is the dominant energy use, and golf cart charging is a significant energy use in the building.
Utility Bill Analysis
44.4
kBtu/ft2/yr
Energy Use
Annual Energy Use Intensity (EUI)
Based on measured energy use between
December 2023 and November 2024, the
building has an energy use intensity of 44.4
kBtu/sq.ft./yr. 84% of the building’s annual
energy use is attributed to electricity, while
the remaining 16% is attributed to natural
gas.
Monthly Natural Gas Use
Dec 2023-Nov 2024 Compared to Jun 2021-May 2022, Weather Normalized
Monthly Electric Use
Dec 2023-Nov 2024 Compared to Jun 2021-May 2022, Weather Normalized
Annual Energy Use Intensity
Dec 2023-Nov 2024
Electric
Natural Gas
Electric
12/23-11/24
Electric Baseline6/21-5/22
kW
h
Natural Gas12/23-11/24
Natural Gas Baseline
6/21-5/22
Th
e
r
m
s
Dec 2023 - Nov 2024
4,000
6,000
0
50
100
150
0
20
60
2,000
0 Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 2024
Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 2024
40
69
Homewood Golf Course Clubhouse134 135City of Ames Energy Audit City of Ames Energy AuditHomewood Golf Course Clubhouse
Energy Cost
Annual Energy Cost
Based on the measured energy use and utility bills between December 2023 and November 2024, the building’s
annual energy cost is $6,112. The electricity cost attributes 95% of the building’s annual energy cost, while the
remaining 5% is attributed to natural gas. The Annual Energy Cost was slightly higher in 2022 than in 2023 due to
higher natural gas usage.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use from January 2023 to December 2023, the building’s annual carbon emissions
are 30.87 mt CO2e/yr. 94% of the building’s annual CO2e emissions are attributed to electricity, while the
remaining 6% can be attributed to gas.
Utility Bill Analysis
$6,112/yr
Annual Energy Cost Comparison
2021-2023
Annual Carbon Emissions
2023
Annual Energy Costs
Dec 2023-Nov 2024
Electric
Natural Gas
Electric
Natural Gas
Electric
Natural Gas
Me
t
r
i
c
T
o
n
s
C
O
2e
Co
s
t
2023
0
10
30
40
2021 2022 2023
0
$2,000
$6,000
$8,000
20
$4,000
The building ranks in the 60th percentile to 1,041 other peer Park/Recreation buildings in the B3 Benchmarking
tool (40% of Park/Recreation buildings have better performance). This indicates that the building is a good
candidate for energy reduction strategies through retrofits; however, the benchmark results may be skewed due to
high electric golf cart charging loads.
The B3 Benchmark Rating is an easy to understand 1 to 5 star-ranking system. For the energy benchmark, it is
based on the ratio of actual kBtu per square foot compared to the benchmark kBtu per square foot model. A rating
higher than 2 1/2 stars means the building is performing better than expected. A rating less than 2 1/2 stars
indicates greater potential for savings.
Benchmarking
B3 Benchmarking Comparison
Be
n
c
h
m
a
r
k
i
n
g
R
a
t
i
n
g
0
1
3
2
4
5
0 4 12 20 24 32 40 44 52 56 64 68 76 80 88 92 100
Peer Rating
8 16 28 36 48 60 72 84 96
70
Homewood Golf Course Clubhouse136 137City of Ames Energy Audit City of Ames Energy AuditHomewood Golf Course Clubhouse
Methodology
The energy use of the building and energy efficiency measures were analyzed using a benchmarking approach that
separates the metered energy use into heating, cooling, and other end uses. A simplified energy model calculates
the savings of energy conservation measures.
Energy Use Characterization
The following graph shows the benchmarked energy use of the building broken down by end use. Approximately
13% of the energy use in the building is for heating, 14% is for cooling, and 73% is for other uses including lighting,
equipment, and water heating. It is estimated that about half of the energy use in the building is for golf cart
charging and other equipment.
Energy Analysis
Electricity Natural GasEUI(kBtu/sq.ft./yr)
Energy Use Characterization by Energy End Use
Total 44.4
Baseload 32.4
• Interior Equipment
• Interior Lighting
• Domestic Hot Water
• Pumps
• Fans
Cooling 6.2
Heating 5.8
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1 - Mechanical System Replacement with Geothermal Heat Pump (Lower Level)
• Existing Condition: Natural gas-fired unit heater serves cart storage area.
• Proposed Energy Efficiency Measure: Add either air-source or water-source heat pump to replace natural gas-
fired unit heater.
• Recommendation for Implementation: Consider replacing when unit heater reaches end of useful life. At
time of implementation, consider the potential federal government incentive for ground-coupled (geothermal)
systems, which is currently a 30% incentive under Section 48 of the tax code. This incentive is available to
public entities in the form of direct payment and is scheduled for phase out between 2033-2035.
EEM 2 - Hybrid Heat Pump Water Heater
• Existing Condition: Natural gas-fired water heater.
• Proposed Energy Efficiency Measure: Replace with hybrid heat pump water heater.
• Recommendation for Implementation: Consider installing heat pump water heater when current unit requires
replacement.
EEM 3 - Energy Recovery Ventilator
• Existing Condition: Unconditioned outdoor air is introduced directly to heat pump return ducts.
• Proposed Energy Efficiency Measure: Add energy recovery ventilator to pre-condition outdoor air and to
recover energy from exhaust air.
• Recommendation for Implementation: Add whenever feasible if determined to be appropriate – particularly if
any indoor air quality or humidity issues are identified with the building.
Estimated Costs for Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate Incremental Cost
Low High
1 Mechanical System Replacement with
Geothermal Heat Pump (Lower Level)
Replace with natural gas-fired unit heater.$3,000 $1,000 $6,000 $26,000
2 Hybrid Heat Pump Water Heater Replace with natural gas-fired water
heater.
$3,000 $400 $5,350 $6,100
3 Energy
Recovery Ventilator
Do nothing.$0 $0 $5,000 $10,000
Energy Efficiency Measures
71
Homewood Golf Course Clubhouse138 139City of Ames Energy Audit City of Ames Energy AuditHomewood Golf Course Clubhouse
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved1
($/kgCO2e)
Average
Simple
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms Energy
Cost
CO2
Emissions
(kgCO2e)
1 Mechanical
System
Replacement with
Geothermal Heat Pump (Low-
er Level)
HVAC
System
- - 297 $351 2,881 $0.139 -
$0.602
N/A Consider when unit
heater replacement is
required
2 Hybrid Heat Pump Water
Heater
Plumbing
System
(0) (326) 297 $35 2,712 $0.197 -
$0.225
N/A Consider when re-
placement required
3 Energy
Recovery Ventilator
HVAC
System
- 486 14 $44 389 $0.858 -
$1.715
N/A Implement as soon as
feasible
1 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to
have a life of 10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either
15 years for smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-
fired equipment.
Estimated Savings for EEM Bundles
Estimated energy savings from implementing all recommended measures are shown in the following charts. The first
chart shows the savings in annual EUI, the second chart shows the savings in annual energy cost, and the third chart
shows the savings in annual carbon emissions. The columns are described as follows:
• Existing +: Implement EEMs 2 and 3 by adding a hybrid heat pump water heater and energy recovery ventilator.
• GSHP (Warehouse): Implement EEM 1 by replacing natural gas-fired unit heater with ground-coupled water-
source heat pump.
• GSHP (Warehouse) +: Implement EEMs 1-3 to improve mechanical and domestic hot water systems.
Energy Efficiency Measures
Predicted Annual EUI Savings
kB
T
U
/
f
t
2/y
r
Energy Efficiency Measures
Predicted Annual Energy Cost Savings
Predicted Annual Carbon Emissions Savings
kg
C
O
2e
72
141City of Ames Energy Audit
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Parks and Recreation Administration
73
Parks and Recreation Administration142 143City of Ames Energy Audit City of Ames Energy AuditParks and Recreation Administration
Facility Description
Building Contact Information
Building Name Parks and Recreation Administration
Address 1500 Gateway Hills Park Drive
Ames, IA 50014
Building Owner City of Ames
Key Contact Joshua Thompson, Parks and Facilities Superintendent
Building Characteristics
General
Year of original construction: 1930s
Building Climate Zone: 5A
Gross floor area: 9,850 sq.ft.
Total conditioned area: 9,850 sq.ft.
Total number of floors: 2
Conditioned floors above grade: 1
Conditioned floors below grade: 1
Use Type
Primary building use type: Office
Secondary building use type: Assembly/Activity
Major Renovations
Operations
Typical weekly occupancy: Monday through Friday, 7:00 a.m. to 3:30 p.m.
Typical annual occupancy: 52 weeks/year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
The main level exterior walls have batt or blown insulation between wood
studs, 1” to 2” of rigid insulation, and a gypsum board interior finish. The
exterior features new vinyl siding and a new vapor barrier from around 2023.
The basement walls are a mix of uninsulated block and brick, with a stucco
exterior finish.
The window to wall ratio is around 8% and has decreased over time as
windows have been boarded up and enclosed. The windows on the main level
were replaced in 2009 with double-glazed wood-framed operable windows.
The basement has fixed single-glazed wood-framed windows, with storm
windows on 3 of the 4 south facing windows.
The majority of the roof is a pitched roof with asphalt shingles, assumed to
have insulation between ceiling joists based on information shared by staff. A
major renovation in 1982 replaced areas of roof shingles, and additional roof
repairs were conducted around 2005-2006. An addition to the building has
a flat black membrane roof, with two 1” insulation boards and batt insulation
between 2x10 wood joists.
Lighting System
LED replacement lamps have been installed for fluorescent fixtures
throughout most of the space. Lighting controls are typically manual.
HVAC Systems
Building HVAC primarily consists of residential-style natural gas-fired
furnaces with associated air-cooled condensers (air conditioners) providing
cooling. Furnaces do not appear to be provided with outdoor air. Small,
dedicated exhaust fans are provided for restrooms and custodial space.
Plumbing Systems
Domestic hot water is generated by a standard efficiency tank-type natural
gas-fired water heater.
South Elevation
Typical Window on Main Level
Condensing Unit and Gas Service
Multi-Purpose Room Lighting
Typical Furnace
74
Parks and Recreation Administration144 145City of Ames Energy Audit City of Ames Energy AuditParks and Recreation Administration
Water Heater
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on June 3, 2025.
Observations
Building Envelope
• One basement window was missing a storm window. Basement windows
appear to be in poor condition.
• The wood fascia board on the south side is detaching from the building.
Recommend securing the board.
• Stucco finish on basement walls has deteriorated. Recommend repair.
• Roof appears to be approaching or at the end of useful life, though roof
was not accessible during the walk through for further review. Occupant
also noted prior leaks at flat roof location. Recommend further review
of membrane and shingle condition and potential replacement in near
future.
Lighting Systems
• Lighting controls should be updated to more modern types.
HVAC Systems
• No ventilation is apparent in the facility, and there have been moisture
issues in the lower level – when on site, the air quality in the lower level
appeared to be of concern.
Plumbing Systems
• Better efficiency for water heater can be achieved with different
technology.
Basement Missing Storm Window
Detached Wood Fascia Board
Deteriorating Stucco
Basement Moisture Remediation
Monthly Electric Usage
The monthly electricity consumption shows a pattern of higher usage in the summer due to cooling loads.
Monthly Natural Gas Usage
The monthly natural gas consumption shows a pattern of higher usage in the winter due to heating loads. The
relatively small natural gas consumption in the summer is attributed to domestic water heating.
Overview
Metered energy data from May 2020 through December 2024 was collected during the audit and is documented
below. The building uses both electricity and natural gas, and natural gas is the dominant energy source. Due to
the age of the building and issues identified during the walk-through, the building is a good candidate for energy
efficiency retrofits.
Utility Bill Analysis
30.4
kBtu/ft2/yr
Energy Use
Annual Energy Use Intensity (EUI)
Based on measured energy use between
December 2023 and November 2024, the
building has an energy use intensity of 30.4
kBtu/sq.ft./yr. 73% of the building’s annual
energy use is attributed to natural gas, while
the remaining 27% is attributed to electricity.
Monthly Natural Gas Use
Dec 2023-Nov 2024 Compared to Jan 2021-Dec 2021, Weather Normalized
Monthly Electric Use
Dec 2023-Nov 2024 Compared to Jan 2021-Dec 2021, Weather Normalized
Annual Energy Use Intensity
Dec 2023-Nov 2024
Electric
Natural Gas
Electric12/23-11/24
Electric Baseline1/21-12/21
kW
h
Natural Gas12/23-11/24
Natural Gas Baseline1/21-12/21
Th
e
r
m
s
Dec 2023 - Nov 2024
2,000
3,000
0
200
600
800
0
40
1,000
0 Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 2024
Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 2024
20
400
75
Parks and Recreation Administration146 147City of Ames Energy Audit City of Ames Energy AuditParks and Recreation Administration
Energy Cost
Annual Energy Cost
Based on the measured energy use and utility bills between December 2023 and November 2024, the building’s
annual energy cost is $4,338. The electricity cost attributes 56% of the building’s annual energy cost, while the
remaining 44% is attributed to natural gas. The annual energy cost in 2022 exceeded $5,500 which is higher than
in 2021 or 2023.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use from January 2023 to December 2023, the building’s annual carbon emissions
are 23.09 mt CO2e/yr. 62% of the building’s annual CO2e emissions are attributed to electricity and 38% are
attributed to natural gas.
Utility Bill Analysis
$4,338/yr
Annual Energy Cost Comparison
2021-2023
Annual Carbon Emissions
2023
Annual Energy Costs
Dec 2023-Nov 2024
Electric
Natural Gas
Electric
Natural Gas
Electric
Natural Gas
Me
t
r
i
c
T
o
n
s
C
O
2e
Co
s
t
2023
0
20
30
2021 2022 2023
0
$2,000
$4,000
$6,000
10
The building ranks in the 77th percentile to 1,041 other peer Park/Recreation buildings in the B3 Benchmarking
tool (23% of Park/Recreation buildings have better performance). This indicates that the building is a good
performer, and there is opportunity for moderate energy reduction through retrofits.
The B3 Benchmark Rating is an easy to understand 1 to 5 star-ranking system. For the energy benchmark, it is
based on the ratio of actual kBtu per square foot compared to the benchmark kBtu per square foot model. A rating
higher than 2 1/2 stars means the building is performing better than expected. A rating less than 2 1/2 stars
indicates greater potential for savings. While building energy performance is good in comparison to similar facilities,
there are several deficiencies that should be addressed that will negatively impact building energy consumption
(particularly the addition of outdoor air ventilation). This should be considered when prioritizing facility needs.
Benchmarking
B3 Benchmarking Comparison
Be
n
c
h
m
a
r
k
i
n
g
R
a
t
i
n
g
0
1
3
2
4
5
0 4 12 20 24 32 40 44 52 56 64 68 76 80 88 92 100
Peer Rating
8 16 28 36 48 60 72 84 96
76
Parks and Recreation Administration148 149City of Ames Energy Audit City of Ames Energy AuditParks and Recreation Administration
Methodology
The energy use of the building and energy efficiency measures were analyzed using a benchmarking approach that
separates the metered energy use into heating, cooling, and other end uses. A simplified energy model calculates
the savings of energy conservation measures.
Energy Use Characterization
The following graph shows the benchmarked energy use of the building broken down by end use. Approximately
74% of the energy use in the building is for heating, 5% is for cooling, and 21% is for other uses including lighting,
equipment, and water heating.
Energy Analysis
Electricity Natural GasEUI(kBtu/sq.ft./yr)
Energy Use Characterization by Energy End Use
Total 30.4
Baseload 6.2
• Interior Equipment
• Interior Lighting
• Domestic Hot Water
• Pumps
• Fans
Cooling 1.6
Heating 22.6
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1A - Mechanical System Replacement with Air Source Heat Pump
• Existing Condition: Natural gas-fired furnaces and air-cooled condensing units (air conditioners).
• Proposed Energy Efficiency Measure: Air-source heat pumps paired with high-efficiency natural gas-fired
furnaces.
• Recommendation for Implementation: Consider implementation when existing furnaces or condensing units
require replacement.
EEM 1B - Mechanical System Replacement with Ground Source Heat Pump
• Existing Condition: Natural gas-fired furnaces and air-cooled condensing units (air conditioners).
• Proposed Energy Efficiency Measure: Provide ground-coupled (geothermal) heat pumps to replace existing
furnaces and condensing units (preliminary site review appears feasible).
• Recommendation for Implementation: Consider implementation when existing furnaces or condensing
units require replacement. At time of implementation, consider the potential federal government incentive
for ground-coupled (geothermal) systems, which is currently a 30% incentive under Section 48 of the tax
code. This incentive is available to public entities in the form of direct payment and is scheduled for phase out
between 2033-2035.
EEM 2 - Energy Recovery Ventilator
• Existing Condition: Building is not provided with outdoor air.
• Proposed Energy Efficiency Measure: Add energy recovery ventilator to provide outdoor air and exhaust air,
while limiting energy consumption.
• Recommendation for Implementation: As soon as possible (may increase energy consumption, but will help to
address indoor air quality concerns in space).
EEM 3 - Dimming Daylighting
• Existing Condition: Building odes not have any automatic lighting controls.
• Proposed Energy Efficiency Measure: Add daylight dimming lighting controls wherever appropriate or required
by code.
• Recommendation for Implementation: Coordinate with lighting replacement. Will have immediate benefit, but
will be appropriate to coordinate replacement of lighting and controls together.
EEM 4 - Lighting Occupancy and Vacancy Sensor Controls
• Existing Condition: Building does not have any automatic lighting controls.
• Proposed Energy Efficiency Measure: Add occupancy- or vacancy-based lighting controls wherever appropriate
or required by code.
• Recommendation for Implementation: Coordinate with lighting replacement. Will have immediate benefit, but
will be appropriate to coordinate replacement of lighting and controls together.
Energy Efficiency Measures
77
Parks and Recreation Administration150 151City of Ames Energy Audit City of Ames Energy AuditParks and Recreation Administration
Energy Efficiency Measures
EEM 5 - Heat Pump Water Heater
• Existing Condition: Hot water generated by tank-type standard efficiency water heater.
• Proposed Energy Efficiency Measure: Heat pump water heater (expected to meet building demands).
• Recommendation for Implementation: When current water heater replacement is necessary, utilize heat pump
water heater as appropriate (may work well in current space due to higher summer temperatures in area – need
to verify there won’t be issues during heating season with reducing space temperature).
EEM 6 - Increase Roof Insulation
• Existing Condition: The existing pitched roofs have insulation between ceiling joists that is expected to be below
the current energy code minimum requirements for thermal performance.
• Proposed Energy Efficiency Measure: In areas with pitched roofs, add additional insulation to increase the
overall thermal performance to R-30.
• Recommendation for Implementation: Recommend implementing at time of future roof renovations. Note
that drawings of the pitched roof insulation were not available and the attic was inaccessible during the site
walkthroughs, so further verification of the existing conditions should be conducted to determine the amount
of additional insulation required to achieve R-30. For the purposes of costing, the existing pitched roofs are
assumed to perform at R-14.
EEM 7 - Basement Window Replacement
• Existing Condition: The single-glazed wood-framed windows with storm windows in the basement are in poor
condition. One storm window is missing.
• Proposed Energy Efficiency Measure: Replace windows with a high-performing thermally-broken window
assembly that is better than current energy code minimums. This EEM evaluates the impact of a window
assembly with a U-factor of 0.36 and a SHGC of 0.38.
• Recommendation for Implementation: Recommend implementing as soon as possible and simultaneously with
other basement renovations. If window replacement is not feasible in the near future, recommend replacing the
missing storm window as soon as possible and recaulking the basement windows.
Estimated Costs for Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate Incremental Cost
Low High
1A Mechanical System
Replacement with Air Source Heat Pump
Direct replacement of existing system $75,000 $5,000 $7,500 $20,000
1B Mechanical System
Replacement with Ground Source Heat
Pump
Direct replacement of existing system $75,000 $6,000 $44,000 $94,000
2 Energy Recovery Ventilator Do nothing $0 $0 $5,000 $10,000
3 Dimming Daylighting Do nothing $0 $0 $3,734 $9,850
4 Lighting Occupancy and Vacancy Sensor
Controls
Do nothing $0 $0 $6,343 $19,700
5 Heat Pump Water Heater Direct replacement of existing water
heater
$3,000 $400 $3,100 $3,850
6 Increase Roof Insulation Do nothing $0 $0 $8,891 $15,332
7 Basement Window Replacement Energy Code-Compliant Window
Replacement
$3,766 $0 $0 $753
Energy Efficiency Measures
78
Parks and Recreation Administration152 153City of Ames Energy Audit City of Ames Energy AuditParks and Recreation Administration
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved1
($/kgCO2e)
Simple
Average
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms Energy
Cost
CO2
Emissions
(kgCO2e)
1A Mechanical System
Replacement with Air Source
Heat Pump
Mechan-
ical
(51) (17,007) 2,644 $526 16,805 $0.030 -
$0.079
N/A Implement at end of
system life
1B Mechanical System
Replacement with Ground
Source Heat Pump
Mechan-
ical
(3) (12,988) 2,644 $942 18,896 $0116 -
$0.249
N/A
2 Energy
Recovery Ventilator
Mechan-
ical
- (389) 335 $249 3,048 $0.082 -
$0.164
N/A Implement as soon as
feasible
3 Dimming Daylighting Lighting 1 1,124 (19) $100 400 $0.466 -
$1.230
N/A Implement as soon as
feasible
4 Lighting Occupancy and
Vacancy Sensor Controls
Lighting 2 1,520 (28) $133 519 $0.611 -
$0.1.898
N/A
5 Heat Pump Water Heater Service
Water
Heating
(1) (230) 79 $44 647 $0.479-
$0.595
N/A Implement at end of
system life
6 Increase Roof Insulation Building
Envelope
1 249 288 $275 2,924 $0.101 -
$0.175
N/A Implement with other
major roof improve-
ments
7 Basement Window
Replacement
Building
Envelope
- 486 23 $70 476 $0 - $0.053 5.4 Implement as soon as
feasible
1 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the carbon
emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the purposes
of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to have a life of
10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either 15 years for
smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-fired equipment.
Estimated Savings for EEM Bundles
Estimated energy savings from implementing all recommended measures are shown in the following charts. The first
chart shows the savings in annual EUI, the second chart shows the savings in annual energy cost, and the third chart
shows the savings in annual carbon emissions. The columns are described as follows:
• Existing +: Implement EEMs 2-7 to improve ventilation, lighting, building envelope, and domestic hot water
systems.
• Air Source Heat Pumps: Implement EEM 1A to improve mechanical systems.
• Air Source Heat Pumps +: Implement EEM 1A, and EEMs 2-7 to improve mechanical, ventilation, lighting, building
envelope and domestic hot water systems.
• Water Source Heat Pumps: Implement EEM 1B to improve mechanical systems.
• Water Source Heat Pumps +: Implement EEM 1B, and EEMs 2-7 to improve mechanical, ventilation, lighting,
building envelope and domestic hot water systems.
Energy Efficiency Measures
Predicted Annual EUI Savings
kB
T
U
/
f
t
2/y
r
Predicted Annual Energy Cost Savings
Predicted Annual Carbon Emissions Savings
kg
C
O
2e
Energy Efficiency Measures
79
155City of Ames Energy Audit
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Airport Terminal
80
Airport Terminal156 157City of Ames Energy Audit City of Ames Energy AuditAirport Terminal
Facility Description
Building Contact Information
Building Name Airport Terminal
Address 2520 Airport Drive
Building Owner City of Ames
Key Contact Nikki Kyle, Fixed Base Operator Manager, Central Iowa Air
Building Characteristics
General
Year of original construction: 2017
Building Climate Zone: 5A
Gross floor area: 6,973 sq.ft.
Total conditioned area: 6,973 sq.ft.
Total number of floors: 1
Conditioned floors above grade: 1
Conditioned floors below grade: 0
Use Type
Primary building use type: Airport terminal
Secondary building use type: Office
Major Renovations
N/A
Operations
Typical weekly occupancy: Weekdays from 6:00 a.m. to 7:00 p.m.
Weekends from 7:00 a.m. to 7:00 p.m.
Typical annual occupancy: 52 weeks/year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
The exterior walls have metal panel cladding with 3” of rigid insulation. The
primary wall assembly uses 6” metal studs, with sheathing outboard and
gypsum walls inboard of the studs. The secondary wall assembly, located
below windows, uses 6” of concrete with a gypsum board interior finish.
The window to wall ratio is approximately 35%. The windows are double-
glazed aluminum-framed assemblies. Building entrances include glazed
entry doors with vestibules.
The roof is a flat white TPO membrane roof with 5” of rigid insulation above
the roof deck.
Lighting System
Lighting systems throughout the building utilize LED fixtures. Lighting
controls are provided for daylight dimming and occupancy/vacancy as
required by code.
HVAC Systems
Occupied areas of the building are served by residential-style natural
gas-fired furnaces and air-cooled condensing units. An energy recovery
ventilator provides outdoor air and exhaust to the furnaces. Dedicated
exhaust fans serve select areas of the building.
Plumbing Systems
Domestic hot water is generated by a standard efficiency natural gas-fired
water heater.
Condensing Units
Typical Furnaces
Typical Lighting
South Elevation
Pendant Lighting
81
Airport Terminal158 159City of Ames Energy Audit City of Ames Energy AuditAirport Terminal
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on March 14, 2025.
Observations
Building Envelope
• Weatherstripping on vestibule doors can be improved to reduce
infiltration.
• Multiple areas of the exterior metal trim are detaching from the building.
Recommend resecuring these elements.
• The south facing roof overhang provides useful exterior shading to the
south-facing windows. Even with the exterior shading, the passenger
lounge receives strong southern light and interior shades are often
deployed halfway. Occupants noted that shades cannot be deployed fully
due to visibility and safety requirements.
Lighting Systems
• Lighting system is modern and does not have meaningful opportunity for
efficiency improvement – consideration of replacement scheduling may
be appropriate.
HVAC Systems
• Issues were identified with zoning and comfort throughout the building.
When equipment replacement or improvements are implemented,
consider changes to zoning to improve occupant comfort.
Plumbing Systems
• Better efficiency for water heater can be achieved with different
technology.
Passenger Lounge
Loose Screw and Panel
Monthly Electric Usage
The monthly electricity consumption pattern shows a peak in the summer and fall months due to cooling loads and
an increase in occupancy and operation.
Monthly Natural Gas Usage
The monthly natural gas consumption shows a peak in the winter months which can be attributed to heating loads.
Overview
Metered energy data from February 2023 through January 2025 was collected during the audit and is
documented below. The building uses both electricity and natural gas and shows moderate opportunities for
energy efficiency improvements.
Utility Bill Analysis
40.5
kBtu/ft2/yr
Energy Use
Annual Energy Use Intensity (EUI)
Based on measured energy use between
January 2024 and December 2024, the
building has an energy use intensity of 40.5
kBtu/sq.ft./yr. 57% of the building’s annual
energy use is attributed to natural gas, while
the remaining 43% is attributed to electricity.
Monthly Natural Gas Use
Jan 2024-Dec 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Monthly Electric Use
Jan 2024-Dec 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Annual Energy Use Intensity
Jan 2024-Dec 2024
Electric
Natural Gas
Electric
1/24 -12/24
Electric Baseline1/20-12/20
kW
h
Natural Gas1/24-12/24
Natural Gas Baseline
1/20-12/20
Th
e
r
m
s
Jan 2024 - Dec 2024
4,000
6,000
0
200
400
600
0
20
60
2,000
0 Dec 2024Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 2024
40
Dec 2024Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024 Nov 2024
82
Airport Terminal160 161City of Ames Energy Audit City of Ames Energy AuditAirport Terminal
Energy Cost
Energy cost data was not available for the project.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use from January 2023 to December 2023, the building’s annual carbon emissions
are 18.38 mt CO2e/yr. 78% of the building’s annual CO2e emissions are attributed to electricity, while the
remaining 22% can be attributed to gas.
Utility Bill Analysis
Annual Carbon Emissions
2023
Electric
Natural GasMe
t
r
i
c
T
o
n
s
C
O
2e
2023
0
5
15
20
10
The building ranks in the 78th percentile to 3,099 other peer Office buildings in the B3 Benchmarking tool (22%
of Office buildings have better performance). This indicates that the building is a good performer, and there are
opportunities for moderate energy savings through retrofits.
The B3 Benchmark Rating is an easy to understand 1 to 5 star-ranking system. For the energy benchmark, it is
based on the ratio of actual kBtu per square foot compared to the benchmark kBtu per square foot model. A rating
higher than 2 1/2 stars means the building is performing better than expected. A rating less than 2 1/2 stars
indicates greater potential for savings.
Benchmarking
B3 Benchmarking Comparison
Be
n
c
h
m
a
r
k
i
n
g
R
a
t
i
n
g
0
1
3
2
4
5
0 4 12 20 24 32 40 44 52 56 64 68 76 80 88 92 100
Peer Rating
8 16 28 36 48 60 72 84 96
83
Airport Terminal162 163City of Ames Energy Audit City of Ames Energy AuditAirport Terminal
Methodology
The energy use of the building and energy efficiency measures were analyzed using a benchmarking approach that
separates the metered energy use into heating, cooling, and other end uses. A simplified energy model calculates
the savings of energy conservation measures.
Energy Use Characterization
The following graph shows the benchmarked energy use of the building broken down by end use. Approximately
56% of the energy use in the building is for heating, 23% is for cooling, and 21% is for other uses including
lighting, equipment, and water heating.
Energy Analysis
Electricity Natural GasEUI(kBtu/sq.ft./yr)
Energy Use Characterization by Energy End Use
Total 40.5
Baseload 8.5
• Interior Equipment
• Interior Lighting
• Domestic Hot Water
• Pumps
• Fans
Cooling 9.3
Heating 22.7
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1: Air Source Heat Pumps
• Existing Condition: Air-cooled condensing units paired with natural gas-fired furnaces.
• Proposed Energy Efficiency Measure: Air-source heat pumps paired with air handling units with supplemental
electric heating coil – may consider natural gas-fired furnace depending on replacement timing and expected
emissions rate from electric utility.
• Recommendation for Implementation: Consider when equipment replacement is necessary.
EEM 2: Heat Pump Water Heater
• Existing Condition: Standard efficiency natural gas-fired water heater.
• Proposed Energy Efficiency Measure: Heat pump water heater.
• Recommendation for Implementation: Consider when equipment replacement is necessary.
EEM 3: Graphic Solar Film
• Existing Condition: The south-facing windows of the passenger lounge and vestibule are large contributors to
solar heat gain within the building. The passenger lounge also experiences high illuminance levels and direct
sunlight.
• Proposed Energy Efficiency Measure: Apply a graphic solar film on the south-facing windows of the passenger
lounge and vestibule to reduce solar heat gain by 50% and reduce high illuminance levels that may contribute
to thermal and visual discomfort.
• Recommendation for Implementation: Recommend implementing only if thermal comfort issues due to
overheating are a frequent issue in the passenger lounge. The graphic solar film does not have a payback
period and also contributes to increased carbon emissions due to higher heating loads that aren’t offset by
lower cooling loads. If applied, the film must maintain sufficient visibility to the outside for airport security and
operations. The film could also function as a graphic image that welcomes arriving passengers to the airport.
Estimated Costs for Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate Incremental Cost
Low High
1 Air Source Heat Pumps Direct replacement of existing furnace
and condensing unit
$15,000 $1,000 $4,000 $9,000
2 Heat Pump Water Heater Direct replacement of gas-fired water
heater
$3,000 $400 $3,100 $3,850
3 Graphic Solar Film Do nothing $0 $0 $10,499 $15,749
Energy Efficiency Measures
84
Airport Terminal164 165City of Ames Energy Audit City of Ames Energy AuditAirport Terminal
Energy Efficiency Measures
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved1
($/kgCO2e)
Average
Simple
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms Energy
Cost
CO2
Emissions
(kgCO2e)
1 Air Source Heat Pumps HVAC
System
(8,401) 1,652 $559 11,658 $0.023 -
$0.051
11.6 Implement at end of
system life
2 Heat Pump Water Heater Plumbing
System
(0)(558) 120 $46 874 $0.355 -
$0.440
N/A Implement at end of
system life
3 Graphic Solar Film Building
Envelope
1 782 (84) $8 (410) $(0.853) -
$(1.279)
N/A Not recommended
unless needed to
improve thermal
comfort
1 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to
have a life of 10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either
15 years for smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-
fired equipment.
Estimated Savings for EEM Bundles
Estimated energy savings from implementing all recommended measures are shown in the following charts. The first
chart shows the savings in annual EUI, the second chart shows the savings in annual energy cost, and the third chart
shows the savings in annual carbon emissions. The columns are described as follows:
• Non-Mechanical Strategies: Implement EEMs 2 and 3 to improve the domestic hot water systems and building
envelope.
• Mechanical Strategy 1: Implement EEM 1 to improve mechanical systems.
• Mechanical Strategy 1 Plus Non-Mechanical Strategies: Implement EEMs 1-3 to improve the mechanical,
domestic hot water, and building envelope systems.
Predicted Annual EUI Savings
kB
T
U
/
f
t
2/y
r
Non-Mechanical Strategies Mechanical Strategy 1 Mechanical Strategy 1 Plus
Non-Mechanical Strategies
Energy Efficiency Measures
Predicted Annual Energy Cost Savings
Non-Mechanical Strategies Mechanical Strategy 1 Mechanical Strategy 1 Plus
Non-Mechanical Strategies
Predicted Annual Carbon Emissions Savings
kg
C
O
2e
Non-Mechanical Strategies Mechanical Strategy 1 Mechanical Strategy 1 Plus
Non-Mechanical Strategies
85
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CyRide Transit
86
CyRide Transit168 169City of Ames Energy Audit City of Ames Energy AuditCyRide Transit
Facility Description
Building Contact Information
Building Name CyRide Transit
Address 601 North University Boulevard
Ames, IA 50011
Building Owner City of Ames
Key Contact James Rendall, Assistant Director, CyRide
Building Characteristics
General
Year of original construction: 1995
Building Climate Zone: 5A
Gross floor area: 80,021 sq.ft.
Total conditioned area: 80,021 sq.ft.
Total number of floors: 2
Conditioned floors above grade: 2
Conditioned floors below grade: 0
Use Type
Primary building use type: Vehicle storage and service
Secondary building use type: Office
Major Renovations
2005 Addition
2008 Addition
2014 Addition
Operations
Typical weekly occupancy: Weekdays from 8:00 a.m. to 6:00 p.m.
Saturday from 12:00 p.m. to 5:00 p.m.
Typical annual occupancy: 52 weeks/year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
The exterior walls of the garage are concrete masonry units. A variety of
overhead sectional doors types of multiple vintages are located throughout
the garage, ranging from fully to partially glazed. The garage also features
skylights to bring in natural daylight. The 2008 office addition includes
precast concrete panels and metal panel cladding, with aluminum-framed
double-pane window assemblies. Multiple strategies are present for
reducing solar radiation: the lobby glazing has a film applied for solar control,
south-facing second-floor windows have horizontal exterior shades, and
east-facing second-floor windows have vertical exterior shades. One set
of double-glazed operable windows original to the 1980’s facility remains,
located in a storage room. The roof is metal deck, with insulation assumed
to meet or exceed energy code prescriptive requirements at the time of
construction, and a white membrane roof. The 2008 and 2012 roofs are
original, while the remaining roof membranes were replaced in 2017. No
additional insulation was added to the roofs during the 2017 roofing project.
Lighting System
Lighting systems throughout the CyRide Transit facility include a
combination of fluorescent and LED fixtures. Approximately two-thirds of
the office area has LED or converted fixtures, while approximately one-
third remains fluorescent. Approximately two-thirds of the bus storage and
maintenance area remains fluorescent, while approximately one-third has
been upgraded to LED. The bus storage and maintenance areas have manual
controls, with lighting generally on for all but about four hours per day. The
office areas typically have appropriate automatic controls.
HVAC Systems
The CyRide Transit facility includes several areas with different functions,
served by different HVAC systems. Heating for the building is provided by
a few sources, including a heat pump loop tied to the Iowa State University
Power Plant cooling tower system that serves as a heat sink/source for both
water-to-air (water-source) and a heat recovery chiller, two (2) natural gas-
fired boilers, and natural gas-fired unit heaters. Cooling is also provided by
multiple systems, with the heat pump loop tied to the cooling tower system
serving air-source heat pumps for office areas and packaged and split-
system refrigerant units providing cooling to individual zones.
The newer office areas in the building are served by water-source heat
pumps (each typically serving two offices) with perimeter and/or in-floor
hot water heat. Hot water heat is generated by the heat recovery chiller
connected to the power plant cooling towers. Outdoor air is introduced
through an energy recovery ventilator and the area uses a plenum return.
Vehicle Bay Lighting and Skylights
Typical Office Window and Lighting
Roof and Exterior View
Destratification and Capture Exhaust
Hydronic Pumps
Tower Water Heat Exchanger
87
CyRide Transit170 171City of Ames Energy Audit City of Ames Energy AuditCyRide Transit
Facility Description
The original office area in the building is served by a packaged rooftop unit,
which is approximately three to four years old. There is also an exhaust fan
serving this area.
The maintenance office and shop are served by a combination of packaged
rooftop units and split-system air conditioners. There is also an energy
recovery ventilator serving this area. Destratification fans are used in the
maintenance shop to keep heat supplied to the floor area and to prevent the
mezzanine space from overheating.
The bus storage areas are served by a combination of makeup air units and
unit heaters, with devices being a mix of hot water and natural gas-fired. This
portion of the building is equipped with gas detection and alarm systems
that will enable dedicated exhaust fans and makeup air units to remove
exhaust generated contaminants.
Controls in the building are Solidyne Controls. There are some compatibility
and reliability issues with these controls, but they generally appear
functional.
A paint booth is provided with dedicated exhaust and makeup air and is used
less than two hours per day.
Plumbing Systems
The largest load in the building for water heating and consumption is the bus
wash. The system reclaims water to the extent possible.
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on March 19, 2025.
Observations
Building Envelope
• Weatherstripping on several overhead sectional doors should be
repaired to minimize infiltration.
• Issues with freezing pipes were reported in the women’s restroom, and
rust on the bottom of the door frame was observed. Consider opening
the wall with freezing pipes if this continues to be an issue and insulating
pipes if space allows or investigating other options for repair.
Lighting Systems
• Upgrades to LED lighting throughout should be considered as there are
several areas still utilizing fluorescent fixtures/lamps.
• Automatic daylighting controls may be appropriate for the bus storage
and maintenance areas due to skylights, but occupancy-based control is
not appropriate given space functions and potential safety concerns.
HVAC Systems
• Consideration should be given to high-temperature heat pumps to
replace the boilers providing heating to the bus storage areas.
Plumbing Systems
• The largest energy saving opportunity for plumbing is likely at the bus
wash.
Door with Gap at Floor
88
CyRide Transit172 173City of Ames Energy Audit City of Ames Energy AuditCyRide Transit
Monthly Electric Usage
The monthly electric consumption profile shows a slight increase in usage during the winter, likely attributable to
increased operation of the bus wash as well as operation of the heat recovery chiller that produces heating water
for in-floor heat. A certain portion of electrical usage, related to lighting, equipment, and continuous maintenance
sets the baseline energy usage for the building. Most of the portion of the building with cooling, which is the
minority, is served by water-source heat pumps that utilize electricity for both heating and cooling.
Monthly Natural Gas Usage
The monthly natural gas consumption profile shows a typical pattern of higher usage in the winter due to natural
gas serving heating loads, including boilers, gas-fired unit heaters, and packaged rooftop equipment.
Overview
Metered energy data from January 2020 through December 2024 was collected during the audit and is
documented below. While energy use is split fairly evenly between electricity and natural gas, the energy cost and
carbon emissions are dominated by electricity.
Utility Bill Analysis
58.0
kBtu/ft2/yr
Energy Use
Annual Energy Use Intensity (EUI)
Based on measured energy use between
January 2024 and December 2024, the
building has an energy use intensity of 58.0
kBtu/sq.ft./yr. 53% of the building's annual
energy use is attributed to electricity, while
the remaining 47% is attributed to natural
gas.
Monthly Natural Gas Use
Jan 2024-Dec 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Monthly Electric Use
Dec 2023-Nov 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Annual Energy Use Intensity
Dec 2023 - Nov 2024
Electric
Natural Gas
Electric12/23 -11/24
Electric Baseline
1/20-12/20
kW
h
Natural Gas1/24-12/24
Natural Gas Baseline1/20-12/20
Th
e
r
m
s
Dec 2023 - Nov 2024
50,000
100,000
0
2,000
4,000
6,000
0
20
60
0 Nov 2024Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024
40
Nov 2024Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024
Energy Cost
Annual Energy Cost
Based on the measured energy use and utility bills between December 2023 and November 2024, the building’s
annual energy cost is $93,476. 80% of the building’s annual energy cost is attributed to electricity, while the
remaining 20% is attributed to natural gas. Annual energy costs have been consistent throughout the period.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use between January 2023 and December 2023, the building’s annual carbon
emissions is 457 mt-CO2e/year. About 70% of the building’s annual carbon emissions is attributed to electricity
and 30% is attributed to natural gas.
Utility Bill Analysis
$93,476yr
Annual Energy Cost Comparison
2021-2023
Annual Carbon Emissions
2023
Annual Energy Costs
Dec 2023-Nov 2024
Electric
Natural Gas
Electric
Natural Gas
Electric
Natural Gas
Me
t
r
i
c
T
o
n
s
C
O
2e
Co
s
t
2023
0
400
600
2021 2022 20230
$50,000
$100,000
$150,000
200
89
CyRide Transit174 175City of Ames Energy Audit City of Ames Energy AuditCyRide Transit
The building ranks in the 30th percentile to 299 other peer transportation buildings in the B3 Benchmarking tool
(70% of transportation buildings have better performance). This indicates that the building is a good candidate for
energy efficiency improvements.
The B3 Benchmark Rating is an easy to understand 1 to 5 star-ranking system. For the energy benchmark, it is
based on the ratio of actual kBtu per square foot compared to the benchmark kBtu per square foot model. A rating
higher than 2 1/2 stars means the building is performing better than expected. A rating less than 2 1/2 stars
indicates greater potential for savings.
Benchmarking
B3 Benchmarking Comparison
Be
n
c
h
m
a
r
k
i
n
g
R
a
t
i
n
g
0
1
3
2
4
5
0 4 12 20 24 32 40 44 52 56 64 68 76 80 88 92 100
Peer Rating
8 16 28 36 48 60 72 84 96
Methodology
Energy efficiency measures for this facility were analyzed using manual calculations. This approach was selected
due to significant process loads (bus wash, paint booth, vehicle exhaust ventilation systems) that are present in
the building. Normal building energy modeling software is not designed to model process loads, and benchmarking
data is likely unreliable for this type of facility. Manual calculations were performed for specifically identified energy
efficiency measures to determine the potential benefit of each EEM.
Energy Analysis
90
CyRide Transit176 177City of Ames Energy Audit City of Ames Energy AuditCyRide Transit
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1: Water-to-Water Heat Pump Replaces Boilers
• Existing Condition: Two (2) natural gas-fired boilers provide hydronic heating for make-up air units and unit
heaters.
• Proposed Energy Efficiency Measure: Replace boilers with high-temperature water-to-water heat pumps.
• Recommendation for Implementation: Consider when equipment replacement is necessary.
EEM 2: LED Lighting Upgrades
• Existing Condition: Fluorescent lighting remains throughout portion of both the office and bus storage/service
areas.
• Proposed Energy Efficiency Measure: Replace fluorescent lighting with LED.
• Recommendation for Implementation: Consider maintenance costs for lamp replacements and implement
if feasible. It should be noted that the simple payback presented in the Estimated Savings for EEMs table
is calculated based on energy cost savings and first cost only, and does not account for maintenance costs
associated with replacing lamps in existing fluorescent fixtures. Accounting for these maintenance costs
would improve the payback associated with this strategy, but to maintain consistency across the simple
payback calculations presented in the Estimated Savings for EEMs table, the life cycle cost savings associated
with lamp replacement were not included.
EEM 3: Daylight Dimming
• Existing Condition: Lighting throughout bus storage and maintenance areas is manually controlled, with no
dimming.
• Proposed Energy Efficiency Measure: Provide daylight dimming for areas with skylights.
• Recommendation for Implementation: Consider implementation as soon as feasible.
Estimated Costs for Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate Incremental Cost
Low High
1 Water-to-Water Heat Pump Replaces
Boilers
Replace with natural gas-fired boilers.$150,000 $0 $300,000 $600,000
2 LED Lighting Upgrades Do nothing.$0 $0 $201,060 $201,060
3 Daylight Dimming Do nothing.$0 $0 $37,500 $50,000
Energy Efficiency Measures Energy Efficiency Measures
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved1
($/kgCO2e)
Average
Simple
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms Energy
Cost
CO2
Emissions
(kgCO2e)
1 Water-to-Water Heat Pump
to Replace Boilers
Service
Water
Heating
(83,788) 7,862 $(1,873) 35,477 $0.282 -
$0.564
N/A Consider when
replacement is
required
2 LED Lighting Upgrades Lighting - 101,470 - $10,500 52,785 $0.190 -
$0.317
N/A Implement when
feasible
3 Daylight Dimming Lighting - 31,938 - $3,305 16,614 $0.113 -
$0.150
13.2 Implement as soon as
feasible
1 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to
have a life of 10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either
15 years for smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-
fired equipment.
Predicted Annual EUI Savings
kB
T
U
/
f
t
2/y
r
Estimated energy savings from implementing the recommended measures are shown in the following charts. The
first chart shows the savings in annual EUI, the second chart shows the savings in annual energy cost, and the third
chart shows the savings in annual carbon emissions.
91
179City of Ames Energy AuditCyRide Transit178City of Ames Energy Audit
Energy Efficiency Measures
Predicted Annual Energy Cost Savings
Predicted Annual Carbon Emissions Savings
kg
C
O
2e
Ames Intermodal Facility
92
Ames Intermodal Facility180 181City of Ames Energy Audit City of Ames Energy AuditAmes Intermodal Facility
Facility Description
Building Contact Information
Building Name Ames Intermodal Facility
Address 129 Hayward Ave #103
Ames, IA 50014
Building Owner City of Ames
Key Contact James Rendall, Assistant Director, CyRide
Building Characteristics
General
Year of original construction: 2012
Building Climate Zone: 5A
Gross floor area: 111,629 sq.ft. (includes parking garage)
Total conditioned area: 9,603 sq.ft.
Total number of floors: 4
Conditioned floors above grade: 1
Conditioned floors below grade: 0
Use Type
Primary building use type: Parking garage
Secondary building use type: Office
Major Renovations
N/A
Operations
Typical weekly occupancy: Garage: Sunday to Saturday, 24 hours per day
Office: Monday to Friday, from 8:00 a.m. to 5:00 p.m.
Typical annual occupancy: 52 weeks/year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
The conditioned area of the building has CMU exterior walls and aluminum-
framed double-glazed IGU storefront systems. The glazed areas are in the
publicly accessible waiting area and are shaded by a deep overhang above.
The regularly occupied office areas do not have exterior glazing. A heated
detached garage also uses CMU-wall construction and has overhead
sectional doors with translucent polycarbonate panels.
Lighting System
Lighting systems typically consist of Fluorescent-type fixtures, though it
appears transition is underway to LED replacement lamps. Tenant spaces
utilize LED fixtures with line voltage switching and occupancy sensors.
Lighting controls appear to be provided as appropriate for the remainder of
the facility.
HVAC Systems
Several small HVAC systems serve the facility. A ground-coupled
(geothermal) system serves water-source heat pumps for occupied areas.
Two hydronic pumps circulate the ground-source loop fluid. Electric heaters
serve select spaces, such as stairs and storage spaces. A split-system air
conditioner serves the mechanical room. Ventilation for occupied spaces is
provided by a packaged energy recovery ventilator.
Plumbing Systems
Domestic hot water is provided by a small electric resistance tank-type hot
water heater.
Energy Recovery Ventilator
Hydronic Pumps
Office Lighting
Windows and Entrance Lighting
Typical Parking Lighting
Electric Heater
93
Ames Intermodal Facility182 183City of Ames Energy Audit City of Ames Energy AuditAmes Intermodal Facility
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on May 22, 2025.
Observations
Building Envelope
• The doors of the detached garage have noticeable gaps that increase
infiltration and let in debris. Recommend fixing weatherstripping on the
garage doors.
Lighting Systems
• Continued replacement of fluorescent lamps with LED is recommended.
System lighting controls appear to be appropriate.
HVAC Systems
• HVAC systems serve limited portions of the building, and generally
appear to be in good condition.
Plumbing Systems
• The facility has limited domestic water supply (hot or cold) and does
not appear to be a good candidate for investments to reduce energy
consumption.
Other
• For safety, recommend diagnosing and addressing the leak in the
electrical room. The room smelled musty and the electrical cabinet had
visible rust.
• The office space was unoccupied during the walkthrough.
Gap Under Garage Door
Lighting Controls and Electrical Gear
Monthly Electric Usage
The monthly electrical consumption profile shows slightly higher usage in the winter, demonstrating electric
heating in use.
Overview
Metered energy data from January 2020 through November 2024 was collected during the audit and is
documented below. The building is all electric.
Utility Bill Analysis
Energy Use
Annual Energy Use Intensity (EUI)
EUI may not be a relevant metric for this facility, given the small square footage of enclosed building area and large
square footage of open-air parking garage. 100% of the building’s annual energy use is attributed to electricity.
Monthly Electric Use
Dec 2023-Nov 2024 Compared to Feb 2020-Jan 2021, Weather Normalized
Electric
12/23 -11/24
Electric Baseline2/20-1/21
kW
h
30,000
40,000
10,000
0 Nov 2024Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024
20,000
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Ames Intermodal Facility184 185City of Ames Energy Audit City of Ames Energy AuditAmes Intermodal Facility
Energy Cost
Annual Energy Cost
Based on the measured energy use and utility bills between December 2023 and November 2024, the building’s
annual energy cost is $22,646. 100% of the building’s annual energy cost is attributed to electricity. Annual
energy costs have been consistent throughout the period.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use between January 2023 and December 2023, the building’s annual carbon
emissions are 111.09 mt-CO2e/year. 100% of the building’s annual carbon emissions are attributed to electricity.
Utility Bill Analysis
$22,646/yr
Annual Energy Cost Comparison
2021-2023
Annual Carbon Emissions
2023
Annual Energy Costs
Dec 2023-Nov 2024
Electric
Electric
Electric
Me
t
r
i
c
T
o
n
s
C
O
2e
Co
s
t
2023
0
100
150
2021 2022 20230
$10,000
$20,000
$30,000
50
Benchmarking data is unavailable for comparable project types.
Benchmarking
As no energy efficiency measures were identified for this facility, no energy analysis or manual calculations were
completed.
Energy Analysis
No energy efficiency measures (EEMs) are recommended at this time.
Energy Efficiency Measures
95
187City of Ames Energy Audit
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Furman Aquatic Center
96
Furman Aquatic Center188 189City of Ames Energy Audit City of Ames Energy AuditFurman Aquatic Center
Facility Description
Building Contact Information
Building Name Furman Aquatic Center
Address 1635 13th Street
Ames, IA 50010
Building Owner City of Ames
Key Contact Hugo Swanepoel, Parks and Facilities Supervisor
Building Characteristics
General
Year of original construction: 2009
Building Climate Zone: 5A
Gross floor area: 6,485 sq.ft.
Total conditioned area: 6,485 sq.ft.
Total number of floors: 1
Conditioned floors above grade: 1
Conditioned floors below grade: 0
Use Type
Primary building use type: Outdoor swimming pool
Secondary building use type: N/A
Major Renovations
N/A
Operations
Typical weekly occupancy: Sunday through Saturday, 11:00 a.m. - 8:00 p.m.
Typical annual occupancy: ~14 weeks/year (Memorial Day through Labor Day)
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
The above-grade exterior walls are 8” concrete masonry units, with
manufactured stone veneer included on the south facing exterior walls.
Exterior walls located above the south-facing windows of the concession
area are insulated with polyicynene insulation between 2x6 treated studs at
16” on center, with aluminum louvers on “blank-off” sheet metal. Below-grade
exterior walls are concrete foundation walls with a waterproofing membrane.
The floor is a 4” concrete floor slab on 6” compacted gravel drainage course.
The window to wall ratio is 0% for the bathhouse and approximately 7% for
the concessions/mechanical building. The windows are aluminum storefront
systems with double-pane insulated glazing units for the office and lifeguard
area and single-pane glazing units for the concession area. A variety of
exterior doors are used on the project, including hollow metal doors, glazed
doors as part of the storefront system, and uninsulated overhead metal
coiling doors.
The roof system includes asphalt shingles, roofing paper, and 5/8” OSB
attached to pre-engineered wood I-rafters 16” on center. In occupied areas,
there is also an insulated ceiling panel on suspended metal grid.
Lighting System
Lighting fixtures are a combination of fluorescent (interior and building
scale) and metal halide (exterior pole-mount) types. Lighting controls for
occupancy/vacancy control were observed in normally occupied areas.
Exterior lighting is controlled to operate from dusk to dawn.
HVAC Systems
Occupied areas are served by a combination of residential-style furnaces
and condensing units along with separate split-system cooling units (units
are cooling only as building is winterized and does not require heating).
Dedicated exhaust fans serve locker rooms and pool equipment areas.
Plumbing Systems
Domestic hot water is generated by an on-demand, high efficiency
natural gas-fired water heater. The system was originally equipped with a
thermostatic mixing valve, which has been removed.
Pool heating is provided by eighteen (18) water heaters. These water
heaters are high efficiency natural gas-fired units.
Split System Cooling Unit
Electric Furnaces
Exterior Lighting
South Elevation
Pool Equipment
Pool Heaters
97
Furman Aquatic Center190 191City of Ames Energy Audit City of Ames Energy AuditFurman Aquatic Center
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on June 3, 2025.
Observations
Building Envelope
• The building envelope was designed with minimal insulation given the
seasonal use of the building.
• When windows reach the end of their useful life, recommend replacing
with double-pane assemblies with a low Solar Heat Gain Coefficient
throughout.
Lighting Systems
• Given the age and type of fixtures observed, replacement with LED
may be appropriate to both improve energy efficiency and to reduce
maintenance requirements.
HVAC Systems
• Because the building is winterized, air-source heat pumps may not be
appropriate for conditioning interior building spaces.
Plumbing Systems
• Given the number of members of the public using the locker rooms,
including small children, it may be appropriate to reinstall the
thermostatic mixing valve (or to provide a similar device of a different
type).
• While representing an increase in energy consumption, it is
recommended that the supply domestic water temperature be adjusted
to 140 degrees Fahrenheit to reduce potential for legionella growth –
this is more important for the facility due to showering and the potential
that immunocompromised individuals may be using this system.
• Due to potentially high peak domestic hot water demand, particularly
during events such as swim meets, a heat pump water heater for
domestic hot water may not be able to provide adequate capacity for
shower loads.
• Because of the low required outlet temperature for the pool heating
water, there may be opportunity to utilize air-to-water heat pumps to
heat the pools.
Single-Glazed Concession Windows
Overview
Metered energy data from January 2020 through December 2024 was collected during the audit. Due to the
facility not operating in 2020 and some apparent anomalies with natural gas consumption in 2024, data from
2021 through 2023 was considered.
Energy Use
Annual Energy Use Intensity (EUI)
Electricity consumption represents 56% of total building energy consumption, with gas representing 44%. EUI
may not be a relevant metric for this facility, given the small square footage of building area and the fact that
process loads drive the vast majority of energy consumption.
Monthly Electric Usage
The baseline electrical consumption throughout the year reflects the site lighting that remains operational
throughout the year, with more operation during the winter months due to the shorter periods of daylight.
Increased loads in the summer are associated with pumping energy for pool systems and cooling for conditioned
spaces.
Monthly Natural Gas Usage
Natural gas usage exists only during the summer months, associated with pool and domestic water heating. The
facility is winterized, so no heating is provided outside of operating periods.
Utility Bill Analysis
Monthly Natural Gas Use
Jan 2023-Dec 2023 Compared to Jan 2021-Dec 2021, Weather Normalized
Monthly Electric Use
Jan 2023-Dec 2023 Compared to Jan 2021-Dec 2021, Weather Normalized
Electric
1/23 -12/23
Electric Baseline1/21-12/21
kW
h
Natural Gas
1/23-12/23
Natural Gas Baseline1/21-12/21
Th
e
r
m
s
50,000
100,000
0
1,000
3,000
4,000
0 Dec 2023Jan 2023 Feb 2023 Mar 2023 Apr 2023 May 2023 Jun 2023 Jul 2023 Aug 2023 Sep 2023 Oct 2023 Nov 2023
Dec 2023Jan 2023 Feb 2023 Mar 2023 Apr 2023 May 2023 Jun 2023 Jul 2023 Aug 2023 Sep 2023 Oct 2023 Nov 2023
2,000
98
Furman Aquatic Center192 193City of Ames Energy Audit City of Ames Energy AuditFurman Aquatic Center
Energy Cost
Annual Energy Cost
Based on the measured energy use and utility bills between January 2023 and December 2023, the building’s
annual energy cost is $38,165. 84% of the building’s annual energy cost is attributed to electricity, while the
remaining 16% is attributed to natural gas. Annual energy costs have been consistent throughout the period.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use between January 2023 and December 2023, the building’s annual carbon
emissions are 167.68 mt-CO2e/year. About 78% of the building’s annual carbon emissions are attributed to
electricity and 22% are attributed to natural gas.
Utility Bill Analysis
$38,165/yr
Annual Energy Cost Comparison
2021-2023
Annual Carbon Emissions
2023
Annual Energy Costs
Jan 2023-Dec 2023
Electric
Natural Gas
Electric
Natural Gas
Electric
Natural Gas
Me
t
r
i
c
T
o
n
s
C
O
2e
Co
s
t
2023
0
150
200
2021 2022 2023
0
$20,000
$40,000
$60,000
50
100
Benchmarking data is unavailable.
Benchmarking
Methodology
Energy efficiency measures for this facility were analyzed using manual calculations. This approach was selected
due to significant process loads (pumping, water treatment, and heating systems for outdoor pool) that are present
in the facility. Normal building energy modeling software is not designed to model process loads, and benchmarking
data is likely unreliable for this type of facility. Manual calculations were performed for specifically identified energy
efficiency measures to determine the potential benefit of each EEM.
Energy Analysis
99
Furman Aquatic Center194 195City of Ames Energy Audit City of Ames Energy AuditFurman Aquatic Center
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1: Air-to-Water Heat Pumps for Pool Heating
• Existing Condition: Pool heating is accomplished by natural gas-fired heaters.
• Proposed Energy Efficiency Measure: Use air-to-water heat pumps and a heat exchanger to heat pool water.
• Recommendation for Implementation: Consider when pool heating system replacement is required.
EEM 2: LED Lighting Upgrade
• Existing Condition: Fluorescent and metal halide fixtures are utilized.
• Proposed Energy Efficiency Measure: Provide LED fixtures to replace fluorescent and metal halide fixtures.
• Recommendation for Implementation: Consider in near future given the age of existing fixtures and the
potential to reduce maintenance for difficult-to-access fixtures. It should be noted that the simple payback
presented in the Estimated Savings for EEMs table is calculated based on energy cost savings and first cost
only, and does not account for maintenance costs associated with replacing lamps in existing fluorescent or
metal halide fixtures. Accounting for these maintenance costs would improve the payback associated with
this strategy, but to maintain consistency across the simple payback calculations presented in the Estimated
Savings for EEMs table, the life cycle cost savings associated with lamp replacement were not included.
Estimated Costs for Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate Incremental Cost
Low High
1 Air-to-Water Heat Pump Pool Heat Replace with gas-fired water heaters to match existing.$225,000 $0 $390,000 $922,500
2 LED Lighting Upgrade Do nothing.$0 $0 $182,573 $243,430
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved1
($/kgCO2e)
Average
Simple
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms Energy
Cost
CO2
Emissions
(kgCO2e)
1 Air-to-Water Heat Pump Pool
Heat
Service
Water
Heating
(193)(50,785) 7,898 $1,573 50,208 $0.259 -
$0.612
N/A Consider when re-
placement required
2 LED Lighting Upgrade Lighting 36 29,853 - $3,089 15,530 $0.392 -
$0.522
N/A Implement when
feasible
1 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to
have a life of 10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either
15 years for smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-
fired equipment.
Energy Efficiency Measures
Estimated Savings for EEM Bundles
Estimated energy savings from implementing all recommended measures are shown in the following charts. The first
chart shows the savings in annual energy cost and the second chart shows the savings in annual carbon emissions.
The columns are described as follows:
• Air-to-Water Heat Pump (HP): Implement EEM 1 by installing air-to-water heat pumps and a heat exchanger to
heat pool water.
• LED Lighting: Implement EEM 2 by upgrading to LED lighting.
• Air-to-Water Heat Pump (AWHP) and LED Lighting: Implement EEMs 1 and 2 to improve service water heating
and lighting systems.
Energy Efficiency Measures
Predicted Annual Energy Cost Savings
Predicted Annual Carbon Emissions Savings
kg
C
O
2e
100
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Ames/ISU Ice Arena
101
Ames/ISU Ice Arena198 199City of Ames Energy Audit City of Ames Energy AuditAmes/ISU Ice Arena
Facility Description
Building Contact Information
Building Name Ames/ISU Ice Arena
Address 1507 Gateway Hills Park Drive
Ames, IA 50014
Building Owner City of Ames and Iowa State University
Key Contact Michael Lady, Ice Arena Manager
Building Characteristics
General
Year of original construction: 2001
Building Climate Zone: 5A
Gross floor area: 44,632 sq.ft.
Total conditioned area: 44,632 sq.ft.
Total number of floors: 2
Conditioned floors above grade: 2
Conditioned floors below grade: 0
Use Type
Primary building use type: Ice rink/arena
Secondary building use type: Support areas (locker rooms, meeting rooms)
Major Renovations
N/A
Operations
Typical weekly occupancy: Weekdays from 5:30 a.m. to 10:30 p.m.
Weekends from 7:00 a.m. to 10:30 p.m.
Typical annual occupancy: 52 weeks/year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
There are two primary types of above-grade exterior walls: an insulated
metal building wall panel system with batt insulation and a concrete masonry
unit (CMU) wall with insulation-filled cores. The window to wall ratio is 2%.
The windows are fixed aluminum-framed double-pane insulated glazing unit
assemblies. The main entry doors are part of a glazed storefront system. The
primary roof is a standing seam metal panel room system with batt insulation
and no continuous insulation. The lower roof is an EPDM roof system with
2” of continuous rigid insulation over a metal deck. The floor is a 5” concrete
slab on a vapor barrier and 4” of porous fill.
Lighting System
Lighting fixture types and ages vary throughout the building. Fixtures above
the ice sheet were replaced approximately four to five years ago, with new
LED fixtures. Some down lights utilize compact fluorescent lamps. Existing
fluorescent fixtures have had LED tube replacements (single lamp at a time)
as lamp replacements are necessary. Exterior signage was upgraded from
neon to LED. Lighting controls throughout the building are typically line-
voltage type, with no automatic controls.
HVAC Systems
There are several unique HVAC systems serving the Ice Arena facility. The
main arena area, including the ice sheet, is served by a dedicated air handling
system with desiccant dehumidification capabilities. There are also natural
gas-fired infrared radiant heaters that provide heating for spectator and
circulation areas and wall mounted exhaust fans that operate as needed.
The air handling system and exhaust fans are original to the building, but the
radiant heaters were replaced recently.
Meeting spaces, locker rooms, and office areas are served by packaged
rooftop units, providing all heating, cooling and ventilation to these zones.
Dedicated exhaust fans serve the locker room areas, along with the
refrigeration machine room for the ice making system. Packaged rooftop
units and exhaust fans generally appear to be original to the building.
The refrigeration system for the ice sheet currently utilizes refrigerant R-22,
and consists of compressors, an evaporative condenser, heat exchanger,
evaporator, pumps, and associated accessories. The evaporative condenser
was replaced in 2016, but other components are typically original, though
some have been upgraded. There are no centralized controls optimizing
system interaction or performance between different building systems and
components.
Plumbing Systems
The building is served by three standard efficiency natural gas-fired water
heaters. These water heaters provide water for locker room usage along
with other normal plumbing loads.
Evaporative Condenser Sump & Pump
Ice System Compressors
East Elevation
Ice Rink Lighting
Ice System Heat Exchanger
Glycol System Pumps
102
Ames/ISU Ice Arena200 201City of Ames Energy Audit City of Ames Energy AuditAmes/ISU Ice Arena
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on June 3, 2025.
Observations
Building Envelope
• The main entrance does not include a vestibule. Condensation was
present on the interior side of the entrance doors.
• Building staff noted that direct sun hits the ice from the east window
at the stairwell, contributing to localized ice melt and visual discomfort.
Recommend installing a motorized automatic interior shade, with manual
override controls.
• Building staff noted area of previous leak in office.
• Concrete spalling on exterior CMU wall. Recommend monitoring and
repair as needed.
• Recommend replacing overhead doors with insulated sectional doors at
end of life.
Lighting Systems
• Daylighting is likely not a good solution for most of this building, but there
may be opportunities at the main entrance and stair area.
• Occupancy/vacancy controls would likely be beneficial for several areas
in the building.
• Updating fixtures with native-LED devices may be a better long-term
solution than installing retrofit-style LED bulbs.
HVAC Systems
• Several HVAC systems appear to be at or near their expected useful
lives. Specifically packaged rooftop units are over twenty years old
and would be expected to last fifteen to twenty years. The air handling
Main Entrance
East Window at Stairs
Spalling CMU
system serving the arena area is also original to the building and is located outdoors. It is likely that this
unit should be expected to last twenty-five to thirty years at most, so it is likely near the end of its useful
life. Equipment replacement has not been included as an energy efficiency measure, as there aren't clear
improvements available for the current components, other than small efficiency improvements from newer
equipment or systems (the largest unit is desiccant system requiring high-temperature regeneration that can
only currently be achieved by either natural gas or electric heat.
• The lack of coordinated controls between systems likely limits the potential for improving energy efficiency,
though there are likely opportunities to shift loads between systems. Control upgrades are likely beneficial for
this facility, however there likely aren't significant opportunities for energy savings without integrating process
systems and HVAC systems to move energy back and forth between systems. This approach will require
detailed analysis and coordination between system components that is beyond the scope of this audit.
Plumbing Systems
• Efficiency and capacity of the system may be appropriate for review when replacement is required.
• Current heat pump water heater technology is likely not cost effective for the loads required for large-scale
showering needed for multiple hockey teams or similar larger groups.
Monthly Electric Usage
Monthly electric usage varies somewhat depending on season, but due to the significant portion of energy usage
attributable to the ice-making system, and the relatively constant interior temperature, there is a significant
baseline of electric energy utilization throughout the year.
Monthly Natural Gas Usage
Natural gas usage varies throughout the year, with peaks during the heating season. Similar to electric usage, the
difference between summer and winter is not as great as might be expected due to the lower heating requirements
in large portions of the building and the natural gas consumption during the summer associated with regenerating
desiccant in the dehumidification unit used to control space relative humidity.
Overview
Metered energy data from January 2020 through December 2024 was collected during the audit and is
documented below. While energy use is split fairly evenly between electricity and natural gas, the energy cost and
carbon emissions are dominated by electricity.
Utility Bill Analysis
128.7
kBtu/ft2/yr
Energy Use
Annual Energy Use Intensity (EUI)
Based on measured energy use between
December 2023 and November 2024,
the building has an energy use intensity of
128.7 kBtu/sq.ft./yr. Electricity consumption
represents 58% of total building energy
consumption, with gas representing 42%.
Monthly Natural Gas Use
Dec 2023-Nov 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Monthly Electric Use
Dec 2023-Nov2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Annual Energy Use Intensity
Dec 2023-Nov 2024
Electric
Natural Gas
Electric
12/23 -11/24
Electric Baseline1/20-12/20
kW
h
Natural Gas12/23-11/24
Natural Gas Baseline1/20-12/20
Th
e
r
m
s
Dec 2023 - Nov 2024
50,000
100,000
0
1,000
3,000
4,000
0
20
60
0 Nov 2024Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024
40
Nov 2024Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024 Jun 2024 Jul 2024 Aug 2024 Sep 2024 Oct 2024
2,000
103
Ames/ISU Ice Arena202 203City of Ames Energy Audit City of Ames Energy AuditAmes/ISU Ice Arena
Energy Cost
Annual Energy Cost
Based on the measured energy use and utility bills between January 2023 and December 2023, the building’s
annual energy cost is $122,244. 83% of the building’s annual energy cost is attributed to electricity while the
remaining 17% is attributed to natural gas. Annual energy costs have been consistent throughout the period.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use between January 2023 and December 2023, the building’s annual carbon
emissions are 550.95 mt-CO2e/year. 72% of the building’s annual carbon emissions are attributed to electricity
while the remaining 28% are attributed to natural gas.
Utility Bill Analysis
$122,244yr
Annual Energy Cost Comparison
2021-2023
Annual Carbon Emissions
2023
Annual Energy Costs
Dec 2023-Nov 2024
Electric
Natural Gas
Electric
Natural Gas
Electric
Natural Gas
Me
t
r
i
c
T
o
n
s
C
O
2e
Co
s
t
2023
0
400
600
2021 2022 2023
0
$50,000
$100,000
$150,000
200
The building ranks in the 28th percentile to 113 other peer Ice Arena buildings in the B3 Benchmarking tool (72%
of Ice Arena buildings have better performance). This indicates that the building is a great candidate for energy
efficiency improvements.
The B3 Benchmark Rating is an easy to understand 1 to 5 star-ranking system. For the energy benchmark, it is
based on the ratio of actual kBtu per square foot compared to the benchmark kBtu per square foot model. A rating
higher than 2 1/2 stars means the building is performing better than expected. A rating less than 2 1/2 stars
indicates greater potential for savings.
Benchmarking
B3 Benchmarking Comparison
Be
n
c
h
m
a
r
k
i
n
g
R
a
t
i
n
g
0
1
3
2
4
5
0 4 12 20 24 32 40 44 52 56 64 68 76 80 88 92 100
Peer Rating
8 16 28 36 48 60 72 84 96
104
Ames/ISU Ice Arena204 205City of Ames Energy Audit City of Ames Energy AuditAmes/ISU Ice Arena
Methodology
Energy efficiency measures for this facility were analyzed using manual calculations. This approach was selected
due to significant process loads (refrigeration system for ice sheet) that are present in the building. Normal building
energy modeling software is not designed to model process loads, and benchmarking data is likely unreliable for
this type of facility. Manual calculations were performed for specifically identified energy efficiency measures to
determine the potential benefit of each EEM.
Energy Analysis
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1: Entry Vestibule Addition
• Existing Condition: The main entrance does not include a vestibule and entry doors have condensation on the
inside surface. The lack of a vestibule contributes to undesirable heat and humidity gain during the summer,
undesirable heat loss during the winter, and reduced thermal comfort.
• Proposed Energy Efficiency Measure: Install an interior glazed storefront system with double doors at the
entrance to create a vestibule.
• Recommendation for Implementation: Recommend implementing as soon as feasible. There is sufficient
space in the current entry to fit a vestibule up to 22’ long. Although this measure does not have a payback, it
will help improve thermal comfort and reduce infiltration.
EEM 2: Increase Roof Insulation
• Existing Condition: The primary roof is a sloped standing seam metal panel room system with batt insulation
and no continuous insulation. The lower roof is a flat ballasted membrane roof system with 2” of continuous rigid
insulation.
• Proposed Energy Efficiency Measure: Increase the roof thermal performance to R-30.
• Recommendation for Implementation: Recommend further analysis of this efficiency measure as the roof
approaches its end of life. Increased roof insulation is recommended for improved energy efficiency and cost
savings, but a full structural analysis of the engineered metal building system would be required to confirm
additional roof loads are acceptable.
Estimated Costs for Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate Incremental Cost
Low High
1 Entry Vestibule Addition Do nothing $0 $0 $16,059 $19,969
2 Increase Roof Insulation Sloped roof: replace with energy
code-compliant metal building roof
system
Flat roof: replace roof membrane without
adding insulation
$598,524 $0 $32,424 $90,511
Energy Efficiency Measures
105
Ames/ISU Ice Arena206 207City of Ames Energy Audit City of Ames Energy AuditAmes/ISU Ice Arena
Energy Efficiency Measures
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved1
($/kgCO2e)
Average
Simple
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms Energy
Cost
CO2
Emissions
(kgCO2e)
1 Entry Vestibule Addition Envelope - - 297 $23 95 $5.635 -
$7.007
N/A Recommend imple-
menting as soon as
feasible.
2 Increase Roof Insulation Envelope (0) 10,080 3,006 $4,049 20,276 $.053 -
$0.149
15.2 Recommend
implementing at
end of roof system
life, pending further
analysis
1 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to
have a life of 10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either
15 years for smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-
fired equipment.
Estimated Savings for EEM Bundles
Estimated energy savings from implementing all recommended measures are shown in the following charts. The first
chart shows the savings in annual EUI, the second chart shows the savings in annual energy cost, and the third chart
shows the savings in annual carbon emissions. The columns are described as follows:
• Vestibule: Implement EEM 1 to improve the building envelope by adding an entry vestibule.
• Roof Insulation: Implement EEM 2 to improve building envelope by increasing the roof's thermal performance.
• Combined Envelope: Implement EEMs 1 and 2 to improve the building envelope.
Energy Efficiency Measures
Predicted Annual EUI Savings
kB
T
U
/
f
t
2/y
r
Predicted Annual Energy Cost Savings
Predicted Annual Carbon Emissions Savings
kg
C
O
2e
106
209City of Ames Energy Audit
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Water Treatment Plant
107
Water Treatment Plant210 211City of Ames Energy Audit City of Ames Energy AuditWater Treatment Plant
Facility Description
Building Contact Information
Building Name Water Treatment Plant
Address 1800 E 13th Street
Ames, IA 50010
Building Owner City of Ames
Key Contact Calvin Forte, Water Plant Superintendent
Building Characteristics
General
Year of original construction: 2017
Building Climate Zone: 5A
Gross floor area: 103,233 sq.ft.
Total conditioned area: 103,233 sq.ft.
Total number of floors: 4
Conditioned floors above grade: 3
Conditioned floors below grade: 1
Use Type
Primary building use type: Water treatment plant
Secondary building use type: Office
Major Renovations
N/A
Operations
Typical weekly occupancy: 24 hours/day, 7 days/week.
Typical annual occupancy: 52 weeks/year
% of building owned: 100%
% of building leased: 0%
Facility Description
System Descriptions
Building Envelope
The majority of above-grade exterior walls are 12” insulated precast
concrete panels. A few wall types in administration and operations areas
include an additional 4” of sprayed insulation inboard of the precast concrete
panel, in between metal studs and finished with gypsum board. Below-grade
walls are cast-in-place concrete.
The window to wall ratio is approximately 10%. The windows are primarily
fixed aluminum-framed double-pane insulated glazing unit assemblies, with
some operable windows. Exterior shading devices are located on select
south-, west-, and east-facing windows. Overhead sectional doors range
from fully glazed to partially glazed. The roof assembly includes a white
roof membrane and 4” of continuous rigid insulation over a concrete roof
structure.
Lighting System
Interior lighting fixtures throughout the Water Treatment Facility typically
utilize fluorescent lamps. Lighting controls for occupancy/vacancy appear to
be installed throughout the building.
HVAC Systems
Several systems serve different areas of the Water Treatment facility. A
modular central plant system generates heating and chilled water to serve
the building. This central plant includes a heat recovery chiller, boilers,
pumps, heat exchangers, and a closed-circuit cooling tower. The system
can use raw water as a heat sink or source, as well as a cooling tower as
a heat sink. Natural gas-fired boilers provide heat when adequate heat is
not available from raw water. Multiple air handling units of different types
and configurations serve different areas of the building. A desiccant
dehumidification unit with a direct-fired natural gas burner regeneration
section provides dehumidification during the cooling season. Terminal
heating and cooling units provide conditioning for many spaces throughout
the facility.
Plumbing Systems
Domestic hot water is generated by two large-capacity natural gas-
fired water heaters and one water-to-water heat exchanger fed from the
heating hot water system. Recirculation pumps are provided to maintain
temperature in domestic hot water loops.
Hydronic System Controls
Water Treatment Area Lighting
Heat Recovery Chiller
East Elevation
Energy Recovery Ventilator
Entrance Stair Lighting
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Water Treatment Plant212 213City of Ames Energy Audit City of Ames Energy AuditWater Treatment Plant
Notable Conditions Observed
Assessment Date
The building walkthrough was conducted on June 3, 2025.
Observations
Lighting Systems
• The use of fluorescent lighting throughout the facility provides the most
likely opportunity for energy savings.
HVAC Systems
• The packaged central plant system includes control capabilities for
optimizing pumping and system energy usage.
Plumbing Systems
• Because of significant loads required for emergency fixtures (showers
and eyewashes), it is likely not feasible to replace natural gas-fired water
heaters with heat pump units with currently available technology.
Monthly Electric Usage
Monthly electric usage varies somewhat depending on season, but due to the significant portion of energy usage
attributable to the water treatment process loads there is a significant baseline of electric energy utilization
throughout the year. There are increases during the summer months due to cooling load for the facility.
Monthly Natural Gas Usage
Natural gas usage varies somewhat throughout the year, with peaks during the heating season. Similar to electric
usage, the difference between summer and winter is not as great as might be expected due to the natural gas
consumption during the summer associated with regenerating desiccant in the dehumidification unit used to
control space relative humidity.
Overview
Metered energy data from January 2020 through December 2024 was collected during the audit and is
documented below. Electricity dominates the overall energy usage and energy cost for the building. Due to some
gaps in information, the information below is based on the most recent complete year of data.
Utility Bill Analysis
104.0
kBtu/ft2/yr
Energy Use
Annual Energy Use Intensity (EUI)
Based on measured energy use between July
2023 and June 2024, the building has an
energy use intensity of 104.0 kBtu/sq.ft./yr.
Electricity consumption represents 60% of
total building energy consumption, with gas
representing 40%.
Monthly Natural Gas Use
Jul 2023-Jun 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Monthly Electric Use
Jul 2023-Aug 2024 Compared to Jan 2020-Dec 2020, Weather Normalized
Annual Energy Use Intensity
Jul 2023-Jun 2024
Electric
Natural Gas
Electric
7/23 -6/24
Electric Baseline1/20-12/20
kW
h
Natural Gas7/23-6/24
Natural Gas Baseline1/20-12/20
Th
e
r
m
s
Jul 2023 - Jun 2024
150,000
200,000
0
5,000
10,000
15,000
0
50
150
50,000
0
100
Jun 2024Jul 2023 Aug 2023 Sep 2023 Oct 2023 Nov 2023 Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024
100,000
Jun 2024Jul 2023 Aug 2023 Sep 2023 Oct 2023 Nov 2023 Dec 2023 Jan 2024 Feb 2024 Mar 2024 Apr 2024 May 2024
109
Water Treatment Plant214 215City of Ames Energy Audit City of Ames Energy AuditWater Treatment Plant
Energy Cost
Annual Energy Cost
Based on the measured energy use and utility bills between July 2023 and June 2024, the building’s annual energy
cost is $233,562. 84% of the building’s annual energy cost is attributed to electricity while the remaining 16% is
attributed to natural gas. Annual energy costs have been consistent throughout the period.
Carbon Emissions
Annual Carbon Emissions
Based on the measured energy use between January 2023 and December 2023, the building’s annual carbon
emissions are 1,268.86 mt-CO2e/year. 81% of the building’s annual carbon emissions are attributed to electricity
while the remaining 19% are attributed to natural gas.
Utility Bill Analysis
$233,562/yr
Annual Energy Cost Comparison
2021-2023
Annual Carbon Emissions
2023
Annual Energy Costs
Jul 2023-Jun 2024
Electric
Natural Gas
Electric
Natural Gas
Electric
Natural Gas
Me
t
r
i
c
T
o
n
s
C
O
2e
Co
s
t
2023
0
1,000
1,500
2021 2022 2023
0
$100,000
$200,000
$300,000
500
Benchmarking data is unavailable for this building type.
Benchmarking
Methodology
Energy efficiency measures for this facility were analyzed using manual calculations. This approach was selected
due to significant process loads (pumping and water treatment system components) that are present in the facility.
Normal building energy modeling software is not designed to model process loads, and benchmarking data is likely
unreliable for this type of facility. Manual calculations were performed for specifically identified energy efficiency
measures to determine the potential benefit of each EEM.
Energy Analysis
110
Water Treatment Plant216 217City of Ames Energy Audit City of Ames Energy AuditWater Treatment Plant
The following energy efficiency measures (EEMs) offer opportunities to reduce the building’s energy use, operating
energy cost, and carbon emissions.
EEM 1: LED Lighting Retrofit
• Existing Condition: The building is served by mostly fluorescent fixtures for interior lighting.
• Proposed Energy Efficiency Measure: Fluorescent fixtures are replaced by LED fixtures.
• Recommendation for Implementation: Consider implementation as soon as feasible to reduce demand loads
along with electrical consumption. This strategy may be phased to align with normal lamp replacement or
other maintenance processes to avoid interruptions to operations. It should be noted that the simple payback
presented in the Estimated Savings for EEMs table is calculated based on energy cost savings and first cost
only, and does not account for maintenance costs associated with replacing lamps in existing fluorescent
fixtures. Accounting for these maintenance costs would improve the payback associated with this strategy,
but to maintain consistency across the simple payback calculations presented in the Estimated Savings for
EEMs table, the life cycle cost savings associated with lamp replacement were not included.
Estimated Costs for Individual EEMs
Incremental costs for individual EEMs were determined by comparing each proposed EEM’s estimated cost to a
baseline scenario’s estimated cost. Incremental costs listed below account for utility rebates currently available.
Actual costs will vary based on the specific design, selected equipment and manufacturers, installers, and year of
implementation.
EEM
#
EEM Description Baseline Scenario Description Baseline
Scenario
Cost
EEM Rebate Incremental Cost
Low High
1 LED Lighting Retrofit Do nothing $0 $0 $345,405 $575,675
Estimated Savings For Individual EEMs
Estimated savings and recommendations for EEMs are summarized in the table below. Calculations reflect savings
from individual measures only and assume that other measures have not been implemented. For an assessment on
the cumulative savings for bundles of EEMs, please refer to the next section.
EEM
#
EEM Description Type Annual Savings Incremental
Cost / CO2
Emissions
Saved1
($/kgCO2e)
Average
Simple
Payback
(yrs)
Recommendation for
ImplementationPeak
kW
kWh Therms Energy
Cost
CO2
Emissions
(kgCO2e)
1 LED Lighting Retrofit Lighting 14 100,858 - $10,436 43,147 $0.267 -
$0.445
N/A Implement when
determined to be
feasible.
1 Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified in the Appendix. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, building envelope measures are assumed to have a life of 30 years, plumbing (water heaters) are assumed to
have a life of 10 years, lighting systems are assumed to have a life of 20 years, and mechanical equipment is assumed to have a life of either
15 years for smaller air-cooled/air-source equipment or 20 years for larger air-cooled/air-source equipment, air handling equipment, or gas-
fired equipment.
Estimated Savings for EEM Bundles
Estimated energy savings from implementing all recommended measures are shown in the following charts. The first
chart shows the savings in annual EUI, the second chart shows the savings in annual energy cost, and the third chart
shows the savings in annual carbon emissions. The columns are described as follows:
• LED Lighting: Implement EEM 1 for an LED lighting retrofit.
Energy Efficiency Measures Energy Efficiency Measures
Predicted Annual EUI Savings
kB
T
U
/
f
t
2/y
r
Predicted Annual Energy Cost Savings
Predicted Annual Carbon Emissions Savings
kg
C
O
2e
111
219City of Ames Energy Audit
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Solar Photovoltaic Array Assessment
112
Solar Photovoltaic Array Assessment220 221City of Ames Energy Audit City of Ames Energy AuditSolar Photovoltaic Array Assessment
Overview
Scope of the Study
The feasibility of installing a solar photovoltaic (PV) array was reviewed for the following buildings:
• City Hall
• Water Treatment Plant
• Public Works and Fleet
• Electrical Distribution
• Animal Shelter
Financial Feasibility
Installing solar PV at these facilities would have a simple payback of between 12.7 and 14.2 years with an expected
lifespan of at 20-25 years. The primary contributors to this relatively long payback period are the relatively low
electrical utility rates and inability to take advantage of renewable energy tax incentives. Other factors, such as a
hedge against energy cost inflation and reductions in carbon emissions, could be considered to justify the projects.
Another factor negatively affecting the viability of rooftop Solar PV is the age of the roof at each building. The roofs
at these buildings are between nine and ten years old, which means the PV array would only be halfway through its
expected lifespan before needing to be removed (and reinstalled) to accommodate a new roof. This additional cost
is not included in the simple payback calculations below but would add two to three years or more to the payback
period.
This financial analysis includes the rebate available from Ames Municipal Electric and excludes federal financial
incentives. Federal incentives for solar renewable energy projects are currently available under the Section 48E
tax credit, but given recent legislative changes, these credits will be phased out earlier than initially planned. To be
eligible for a 30% federal tax credit, a solar project must begin construction before July 5, 2026 or be placed into
service by December 31, 2027, and meet restrictions related to prohibited foreign entities. Given the accelerated
phase out schedule of the tax credit, these federal incentives have not been accounted for in this solar PV financial
analysis. If the City determines that solar projects can be completed before the tax credit is phased out, then a tax
consultant should be engaged to help navigate the complexities of claiming these incentives for public entities.
Analysis Methodology
1. Two years of owner-provided utility billing data were reviewed for each building to determine maximum available
energy use to offset with PV arrays. All five buildings have energy use that can be offset by installing a PV
array.
2. Ames Municipal Electric supplies power to all buildings in this study and rates are consistent across all
buildings. The electrical usage rate of $0.0653 per kWh and demand charges of $8.01 per KW ($10.71 per Kw
for summer months) combine to yield an average net rate of between $0.08 and $0.11 per kWh depending on a
particular facility’s peak demand. There are no time-of-day charges. These rates are near the average for Iowa
and significantly lower than the national average.
3. To simplify the analysis, this report excludes service charges, variable fuel cost charges, future rate increases,
costs to remove array for roof repair/replacement, and uses a simple payback calculation.
4. U.S. Department of Energy NRAL’s PVWatts Calculator was used to estimate the solar PV array’s annual
energy production. Leveraging the latest solar resource data from NREL’s National Solar Radiation Database,
the calculator uses inputs such as location, system size, module type, array configuration, tilt, azimuth, and
system losses to provide monthly and annual energy output estimates, based on 30 years of historical weather
data to account for interannual variability.
5. A cost of $2,300 per installed DC kilowatt was used for each building regardless of building, array size, or
configuration. This cost includes a $500 per kW (DC) rebate from Ames Municipal Utilities. Installation factors
for each building are similar enough that there shouldn’t be significant variations in the cost of installing each
system. Other factors such as procuring the systems individually or part of a larger project could influence the
cost and can be taken into account when a procurement strategy is developed.
6. To determine how much solar PV capacity could be installed on each building, two key factors were assessed.
First, the area suitable for an array was determined by reviewing shading from adjacent structures, trees, etc.
Second, a module layout factor was applied to account for the racking layout, clearance for maintenance,
setbacks for fire access, and obstructions like HVAC units, vents, skylights, etc. After applying these two
factors, the available roof area was divided by a typical module size (~27 square feet) to determine the quantity
of modules that could be installed.
7. General assumptions for roof mounted systems:
• Premium, monofacial PV modules
• System loss of 14.08% and inverter efficiency of 96%
• Fixed, open rack mounting at 180° azimuth and 10° tilt (typical for a ballasted roof mounting system to
minimize wind load)
• Roof mounted arrays will be a ballasted, low angle system not physically attached to the building structure.
This type of system uses the weight of brick pavers in metal pans to secure the array mounting structure.
113
Solar Photovoltaic Array Assessment222 223City of Ames Energy Audit City of Ames Energy AuditSolar Photovoltaic Array Assessment
Solar PV Analysis
General Conditions
1. All buildings and sites are easily accessible to PV array installation crews and equipment. All have pavement
directly adjacent to building suitable for staging areas, delivery trucks and lifting equipment.
2. Roofs at the buildings studied are generally 9 or 10 years old and in good condition. Refer to analysis and
comment later in this report for applicability to a roof mounted array.
3. Roofs at all sites appear to be adequate for adding 5 pounds per square foot load of PV array. However, a
detailed structural analysis should be performed prior to proceeding with procurement of a new roof mounted
array.
Average Annual Energy Use
Building
Annual Electricity Usage
Consumption (kWh)Cost ($)Carbon Emissions (kgCO2e)
City Hall 1,628,640 $150,676 847,219
Water Treatment Plant 1,898,400 $158,520 987,548
Public Works and Fleet 134,250 $13,607 69,837
Electric Distribution 325,728 $33,713 169,444
Animal Shelter *n/a n/a n/a
* Data not collected due to extensive planned remodel/addition
Potential Array Size Analysis
Building
PV Array Area Proposed PV Array Size**
Gross Roof
Area (sq.ft.)
Area Suitable for Array(sq.ft.)
Module Layout
Factor
Net Area for Modules(sq.ft.)
Max Quantity
of Modules
Quantity of PV
Modules
Array Size
(kW DC)
City Hall 38,116 34,304 50% 17,152 635 635 342.9
Water Treatment Plant 63,700 47,500 55% 26,125 968 968 522.7
Public Works and Fleet 34,560 29,376 50% 14,688 544 192 103.7
Electric Distribution 24,156 21,740 55% 11,957 443 443 239.2
Animal Shelter * n/a 30,000 60% 18,000 667 200 108.0
* Ground mounted array proposed for this facility.
**Array sized to maximize energy usage offset without exceeding average annual electrical usage.
Potential Array Details
Building
PV Array Financials Emissions
Array
Size
(kW DC)
Annual
System
Output
(kWh/yr)
% of
Electric
Usage
Offset
Installed
Cost
($)
Annual
Energy
Cost
Savings
($)
% of
Electric
Cost
Offset
Simple
Payback
(years)
Annual
CO2
Savings
(kgCO2e/
yr)
% of
Electri-
cal CO2 Emis-
sions
Cost
per CO2
Emissions
Saved
($/kgCO2e)*
City Hall 343 443,652 27% $788,670 $55,613 37% 14.2 230,788 27.2%$0.142
Water Treatment Plant 523 676,307 36% $1,202,256 $84,541 53% 14.2 351,815 35.6%$0.142
Public Works and Fleet 104 134,250 100% $238,652 $17,259 127% 14.2 69,837 100.0%$0.142
Electric Distribution 239 309,508 95% $550,206 $38,798 95% 14.2 161,006 95.0%$0.142
Animal Shelter 108 151,185 n/a $248,400 $19,495 n/a 12.7 78,646 n/a $0.132
* Incremental cost per CO2 emissions saved is calculated using a fixed carbon emissions rate as identified earlier in this report. Note that the
carbon emissions rate is expected to decrease over time, so actual costs per CO2 emissions saved will be higher than what is shown. For the
purposes of this calculation, the solar PV array is assumed to have a life of 25 years.
City Hall
Existing Conditions
• The flat white membrane roof is approximately 10
years old and in good condition. It was replaced in
2015.
• The roof is largely open with a limited roof top
equipment to work around.
• Several portions of the roof are not suitable for
installing solar modules due to shading caused by
varying building heights.
• There is limited roof top equipment to work around.
Solar PV Array Feasibility
• Description: roof mounted array with a ten-degree tilt,
non-penetrating ballasted mounting system.
• The roof will accommodate an array that would
reduce electrical usage by approximately 27% with a
financial payback of just over 17 years.
Water Treatment Plant
Existing Conditions
• The flat white membrane roof is approximately 9
years old and in good condition. It is original to the
building (2016).
• Several portions of the roof are not suitable for
installing solar modules due to roof top equipment
and shading caused by varying building heights.
• The is some roof top equipment to work around.
Solar PV Array Feasibility
• Description: roof mounted array with a ten-degree tilt,
non-penetrating ballasted mounting system.
• The roof will accommodate an array that would
reduce electrical usage by approximately 36%. With
a simple payback of about 17 years.
Individual Building Information
Battery Energy Storage System (BESS)
• The feasibility of adding a BESS to this facility was reviewed by request of city staff. A BESS collects energy
during the day to operate plant systems overnight and/or periods without significant daylight. Such a system is
typically used to offset demand or time-of-day utility charges. It can also improve resiliency by supplementing
existing diesel engine backup generators.
• A BESS is typically viable for facilities with high electricity cost or time of use rates, high demand charges, and/
or frequent utility outages. A battery system can cost between $300 and $600 per kilowatt hour.
• Adding a BESS is not recommended for this facility due to relatively low electrical consumption, low demand
rates, and a reliable utility connection.
City Hall Roof Area Suitable for PV Array
Water Treatment Plant Roof Area Suitable for PV Array
N Roof Area Suitable for PV
Roof Area
Roof Area Unsuitable for PV
N Roof Area Suitable for PV
Roof Area
Roof Area Unsuitable for PV
114
Solar Photovoltaic Array Assessment224 225City of Ames Energy Audit City of Ames Energy AuditSolar Photovoltaic Array Assessment
Public Works and Fleet
Existing Conditions
• The flat black membrane roof is approximately 9
years old and in good condition. It was replaced in
2016.
• The roof is largely open with some roof top equipment
and skylights to work around.
Solar PV Array Feasibility
• Description: roof mounted array with a ten-degree tilt,
non-penetrating ballasted mounting system.
• This building uses less electricity than a typical
commercial building of similar size due to the lack of
air conditioning and low power needs of the garage
and maintenance areas. As such, a 293.8 kW rooftop
solar PV array covering the maximum possible roof
area would yield 283% more energy than the facility
typically consumes on a yearly basis.
• Due to net-metering regulations, it generally not
advisable to install an array that produces more
than 100% of a building’s electrical consumption.
Reducing the rooftop array to 108 kW would match
the yearly array output with the average yearly
electrical consumption. In both cases the simple
payback is approximately 17 years.
Electrical Distribution
Existing Conditions
• The flat white membrane roof is approximately 9
years old and in good condition. It was replaced in
2016.
• The roof is largely open with a limited roof top
equipment to work around.
Solar PV Array Feasibility
• This building is operated by Ames Municipal Electric
and does not pay for electricity. Given that net-
metering is not a concern for the utility, the maximum
sized roof-top array was used for this study.
Individual Building Information
Public Works and Fleet Roof Area Suitable for PV Array
Electrical Distribution Roof Area Suitable for PV Array
N Roof Area Suitable for PV
Roof Area
Roof Area Unsuitable for PV
N Roof Area Suitable for PV
Roof Area
Roof Area Unsuitable for PV
Coordinating Installation of Solar PV with Existing Roofs
Consideration should be given to the condition and future replacement of existing roofs at each of the buildings.
Aligning the ages of a roof and a solar PV system is critical. Membrane roofs more than 5 years old are generally
poor candidates for rooftop solar installations, as their lifespan is likely to expire well before the 25-year lifespan
of the solar system, necessitating costly removal and reinstallation during roof replacement. Incorporating these
additional costs into the life-cycle analysis of a solar PV system often makes the overall investment financially
unviable. Conversely, roofs nearing or over 20 years old are ideal candidates for re-roofing prior to solar installation,
ensuring a synchronized lifespan and avoiding future disruption and expense.
• Roof Lifespan: Most commercial flat roofs (e.g., TPO, EPDM, or PVC membranes) have a lifespan of 20–30
years, depending on material, maintenance, and climate. At 10 years, the roof is roughly at the midpoint in its life
cycle, increasing the risk of major repairs.
• Cost of Removal and Reinstallation: the panels must be removed and reinstalled during major repairs roof
replacement, costing up to $200 per panel in today's dollars. Removing and reinstalling panels during the
system’s 25-year expected lifespan significantly alters the economics of the solar array and can extend the
payback period by two to three years or more.
• Warranty Conflicts: Solar installation warranties often require a roof with a remaining life matching the system’s
duration (20-25 years). Installing on a 10-year-old roof may void the roofing warranty or significantly complicate
claims.
It is not typically recommended to install a new rooftop solar array on a 10-year-old commercial flat roof. If the
building owner chooses to accept the financial costs and the roof is in excellent condition with proper maintenance
history, installation can still proceed with a non-penetrating ballasted system, coordinated with the roofing
warranty. Otherwise, replacing the roof first is the safer, more cost-effective approach, ensuring the solar system’s
25-year lifespan aligns with the roof’s lifespan.
Individual Building Information
Animal Shelter
Existing Conditions
• Due to extensive planned renovations and additions,
a ground mounted array was studied at this location
in lieu of a roof-top array per City’s request.
• Planned building addition and change of use will
dramatically increase energy consumption at this
facility.
Solar PV Array Feasibility
• Description: a 200-module ground mounted array
was studied to demonstrate feasibility at this site.
This size array would take up to 10,000 square feet
of ground area and would likely have a simple payback
of about 15.5 years.Animal Shelter Potential Site Area for PV Array
N Potential Site Area for PV
115
227City of Ames Energy Audit
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Electric Vehicle Charging
Assessment
116
Electric Vehicle Charging Assessment228 229City of Ames Energy Audit City of Ames Energy AuditElectric Vehicle Charging Assessment
Electric Vehicle Charging Assessment
Overview
This study reviews the feasibility and potential costs of installing electric vehicle (EV) charging stations at select
municipal buildings to support the city's sustainability goals and growing EV adoption. While there are publicly
accessible charging stations (i.e. ChargePoint) at several city buildings, this review was limited to non-public
charging applications for city-owned vehicles.
A general analysis indicates ample electrical capacity for installing level 1 and level 2 EV charging at most city
buildings. An example case of new EV chargers at various buildings is included in Table EV2. Quantities and types
of chargers indicated in this table were developed from information provided by the utility department and general
assumptions about adding EVs to the fleet within the next few years.
Existing Public Charging Stations
For reference, the following city buildings have EV chargers available for paid public use. Reviewing potential
locations and consumer demand for additional public charging stations was outside the scope of this study.
• City Hall: 2-vehicle Level 2 charger in west parking lot (ChargePoint)
• Ames Intermodal Facility: 2-vehicle Level 2 charger lower level of structure (ChargePoint)
• Electric Power Plant: 2-vehicle Level 2 charger on E. 5th Street (ChargePoint)
• Ames Public Library: 2-vehicle Level 2 charger in north parking lot (ChargePoint)
Summary of Charging Options
Level 1 EV charging operates at 120 volts and 12–16 amps, delivering 1.4–1.9 kW and adds 3–5 miles of range per
hour. Level 1 is best suited for EVs driven less than 50 miles per day, aren’t used for long distance travel, and are
only in use 10 hours or less per day.
Level 1 key points:
• 20A circuit breaker
• Install cost of $700-1000
• Can take several days to fully charge a typical EV battery.
• Example vehicles: compact cars, light duty trucks and vans, golf carts and other low speed vehicles
Level 2 EV charging operates at 208 or 240 volts single phase and 30–40 amps, delivering 7.2–9.6 kilowatts (kW)
and adds 20–30 miles of range per hour. Level 2 is best suited for moderate to high-mileage applications, making
it ideal for vehicles with daily usage exceeding 50 miles and ability to charge for 8-10 hours between uses (e.g.
overnight).
Level 2 key points:
• 40-60A circuit breaker
• Install cost of $2,500 to $5,000.
• Can fully charge a typical EV sedan or light truck battery in about 8 hours.
• Example vehicles: light to medium-duty trucks, light duty transit vehicles, delivery vehicles, operations support
Level 3 EV charging, also known as “DC Fast Charging” (DCFC), operates at power levels from 175 kW to 500 kW,
delivering 100–250 miles of range in 20–45 minutes. It is ideal for high-mileage or rapid-turnaround applications,
where quick recharges are critical.
Level 3 key points:
• Typically requires a separate utility service and transformer to provide high capacity, 480V three-phase power
• Install cost of $40,000–$60,000 to install, plus new utility service costs
Electric Vehicle Charging Assessment
• Can fully charge a typical EV in less than 45 minutes
• Example vehicles: Heavy-duty trucks, transit vehicles, medium to heavy duty delivery vehicles, emergency
response vehicles
EV Charging at City Buildings
Feasibility Factors
• Quantity and type of charging stations
• Duration and time of day when charger will be used
• Location of charging stations
• Capacity of electrical infrastructure
Cost Factors
• Quantity and type of charging stations
• Sophistication of charging stations (i.e. networking, load management, access control)
• Distance from electrical infrastructure
• Extent of electrical infrastructure modifications, including new utility service for level 3 fast chargers
The capacity of each building to accommodate EV charging is highly dependent on the quantity of EVs and the
time of day when charging will take place. For simplicity, this study has calculated the available excess electrical
capacity at each building regardless of time of day. However, if charging can be limited to off-peak hours (i.e.
overnight, when a building is not occupied and has limited air conditioning load) the electrical infrastructure can
accommodate more charging.
For level 3 DC fast chargers, the charging station location and complexity of a new utility connection are major
cost factors. General cost and feasibility factors are discussed above. Due to the complexity of installation, further
study must be tailored to specific vehicles under consideration, the quantity and location, and their daily usage.
117
231City of Ames Energy AuditElectric Vehicle Charging Assessment230City of Ames Energy Audit
Electric Vehicle Charging Assessment
Table EV1: Building Electrical Characteristics
Building Electric Service Size Total Elec. Ca-
pacity (kW)
Peak Demand
(kW)Available Capacity (kW)Potential Charging Station
Locations for Fleet EVs
Airport Terminal*800A, 120/208V-3ph 230.4 n/a n/a parking lot
Animal Shelter^tbd tbd tbd tbd parking lot
City Hall 1600A, 277/480V-3ph 1063.7 623.0 440.7 west parking lot
Ames Intermodal Facility*600A, 277/480V-3ph 398.9 n/a n/a n/a
CyRide Transit 2000A, 277/480V-3ph 1329.6 294.0 1,035.6 garage
Electrical Admin 400A, 120/208V-1ph 66.6 37.0 29.6 adjacent parking
Electric Distribution 600A, 277/480V-3ph 398.9 239.0 159.9 truck bay, East parking lot
Fire Station 1 400A, 120/208V-3ph 115.2 33.0 82.2 apparatus bay, parking lot
Fire Station 3 400A, 120/208V-3ph 115.2 20.8 94.4 apparatus bay, parking lot
Homewood Clubhouse 400A, 120/208V-1ph 66.6 19.2 47.4 maintenance garage
Ice Arena 1200A-277/480V-3ph 797.8 281.6 516.2 Zamboni
Ames Public Library 1200A-277/480V-3ph 797.8 395.2 402.6 bookmobile garage
Parks & Rec Admin 200A, 120/208V-3ph 57.6 17.1 40.5 parking lot
Public Works & Fleet 800A, 120/208V-3ph 230.4 55.5 174.9 South or North parking
Technical Services Complex 600A, 277/480V-3ph 398.9 98.4 300.5 East parking lot, garage
Water Treatment Plant 2000A, 277/480V-3ph 1329.6 380.8 948.8 South Parking lot
* Peak demand info is not available.
^ Building will be renovated and expanded in 2026.
Table EV2: Adding EV Charging at City Buildings (example case)
Building Available Capacity
(kW)
Quantity of Charging Stations for City
Power Required*
(kW)
Approximate Cost for
Level 1 & 2 Only*
($)
Level 1 Level 2 Level 3*
Airport Terminal n/a 0 0 -0 $-
Animal Shelter tbd 0 1 -8.32 $3,750
City Hall 440.68 8 8 2 79.36 $36,800
Ames Intermodal Facility n/a 0 0 -0 $-
CyRide Transit 1035.6 0 4 2 33.28 $15,000
Electrical Admin 29.56 2 0 -3.2 $1,700
Electric Distribution 159.88 4 4 -39.68 $18,400
Fire Station 1 82.2 2 2 -19.84 $9,200
Fire Station 3 94.4 0 2 -16.64 $7,500
Homewood Clubhouse 47.36 1 0 -1.6 $850
Ice Arena 516.16 0 1 -8.32 $3,750
Ames Public Library 402.56 0 1 -8.32 $3,750
Parks & Rec Admin 40.46 2 0 -3.2 $1,700
Public Works & Fleet 174.89 4 8 4 72.96 $33,400
Technical Services Complex 300.48 2 2 -19.84 $9,200
Water Treatment Plant 948.8 2 2 -19.84 $9,200
*Level 3 fast charging excluded for cost and capacity analysis. Refer to report for more info.
B3 Benchmarking
Facility Comparison
118
B3 Benchmarking Facility Comparison232City of Ames Energy Audit
Facilities that are eligible for a B3 Benchmark Rating are compared below. The B3 Benchmark Rating is an easy to
understand 1 to 5 star-ranking system. For the energy benchmark, it is based on the ratio of actual kBtu per square
foot compared to the benchmark kBtu per square foot model. A rating higher than 2 1/2 stars means the building is
performing better than expected. A rating less than 2 1/2 stars indicates greater potential for savings.
The B3 Peer Rating is another metric for comparing a building's energy performance to peer buildings. For example,
a building that ranks in the 85th percentile performs better than 85% of peer buildings in the B3 database by using
less energy per square foot.
The B3 Benchmarking database did not have sufficient data on certain types of peer facilities, such as parking
facilities, outdoor aquatic centers, and water treatment plants. Therefore the Ames Intermodal Facility, the Furman
Aquatic Center, and the Water Treatment Plant were excluded from the comparison below.
B3 Benchmarking Facility Comparison
B3
P
e
e
r
R
a
t
i
n
g
B3
B
e
n
c
h
m
a
r
k
R
a
t
i
n
g
B3 Benchmark Rating Comparison
B3 Percentile Rating Comparison
2.5
119