Characterization of Cold Climate
ASHPs in Dane County’s
Residential Housing Stock
Prepared for Dane County Office of Energy andClimate Change
JANUARY 2022

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Table of Contents
Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock ................................ 1
Executive Summary ....................................................................................................................................... 4
Figures and Table List .................................................................................................................................... 6
Introduction .................................................................................................................................................. 7
Approach and Methodology ......................................................................................................................... 8
Quantitative Analysis Methodology ......................................................................................................... 8Interview Methodology .......................................................................................................................... 10
Data Analysis Results .................................................................................................................................. 11
Dane County Housing Stock and Heating Fuels ...................................................................................... 11
Savings Analysis – Utility Bill and Carbon Savings ................................................................................... 16
Utility savings per unit ........................................................................................................................ 16
Carbon savings per unit ...................................................................................................................... 17
Total annual Carbon Savings Across Dane County.............................................................................. 19
Air Source Heat Pump Upgrade Cost Analysis ........................................................................................ 20
Upgrade cost per unit ......................................................................................................................... 20
cost to implement per ton of carbon saved ....................................................................................... 21
Interview Results......................................................................................................................................... 22
Themes From Interviews ........................................................................................................................ 22
Case Study 1: Single Family Homeowner with a Propane Heating System ............................................ 23
Case Study 2: Multi-family Owner With Electric Baseboard Heat .......................................................... 24
Recommendations ...................................................................................................................................... 26
ccASHP Electrification Opportunities in the Dane County Housing Stock .............................................. 26
Recommendations In the Electric Resistance Sector .............................................................................. 26
Recommendations and Programmatic Considerations Across All Heating Types .................................. 28
Recommendations In the Fuel-oil and Propane Sector .......................................................................... 29
References .................................................................................................................................................. 31
Appendix A: Quantitative Analysis .............................................................................................................. 32
ResStockTM Database............................................................................................................................... 32
Energy Savings Calculations .................................................................................................................... 32
ASHP Upgrade Cost Estimates ................................................................................................................ 33
Carbon Savings Scenarios ....................................................................................................................... 35©2022 Elevate Energy2Characterization of Cold Climate ASHPs in Dane County’s Residential Housing StockAppendix B: Dane County Housing Stock.................................................................................................... 37
Appendix C: Relationship between heating fuel and income in Dane County ........................................... 39
Appendix D: Recruitment outreach example ............................................................................................. 41©2022 Elevate Energy

3Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Executive Summary
The purpose of this study is to examine the potential for upgrading to cold-climate air-source heatpumps (ccASHPs) across certain housing stocks in Dane County. The scope of this analysis included
residential units (single-family and multi-family) in buildings that do not use natural gas for heating(approximately 80,000 residential units). Opportunities within specific housing stocks were identified
based on the carbon emission reduction potential, utility reduction, and implementation cost. Both theheating and cooling impacts of transitioning to ccASHPs were analyzed. The carbon savings wereconducted across two electricity grid scenarios: (1) business as usual, and (2) substantially more
renewable energy. Carbon savings were also evaluated separately for residential units already witheither central or window unit air-conditioning (approximately two-thirds of units) and units without airconditioning (one-third of units). In addition, 15 interviews were conducted with stakeholders tocontextualize the quantitative findings and identify additional barriers to ccASHP implementation
experienced by those recently pursuing ccASHPs in Dane County. Key recommendations are presented
below.
1. Expand ccASHP electrification efforts to residences with electric resistance heat. Both singlefamily and multi-family electric resistance housing stocks can be converted to ccASHPs in mostscenarios at a lower cost as compared to propane and fuel-oil heated homes, while also
resulting in higher carbon savings and targeting more lower income households.
a. To achieve the highest carbon and utility savings on a per unit basis, offer ccASHP
programs aimed at replacing electric resistance heating in the single-family housing
sector. This sector has the highest per unit carbon savings (3.1-5.2 tons carbon saved
per unit), highest utility savings ($1,100-$1,350 saved annually per unit), and lowest
average simple payback (10 years) of the housing stocks analyzed.
b. To achieve the largest scale of impact, offer ccASHP programs aimed at replacing
electric resistance heating in the multi-family housing sector. This sector has the largest
opportunity for carbon and utility savings based on the number of units (nearly 34,000),with moderate per unit carbon savings (1.0-1.8 tons carbon saved annually per unit) andutility savings ($330-$470). This housing stock also has the lowest expected upgrade
cost ($8,500 per unit).
c. Assist lower income households by prioritizing upgrades in the electric resistanceheating building stock. Lower household incomes are associated with higher prevalenceof electric heated homes in Dane County.
d. Target urban census tracts for ccASHP programs aimed at replacing electric resistanceheating. Electric heating is concentrated in urban areas across Dane County.
2. Consider the following key programmatic recommendations across all heating types.
a. Target ccASHP programs to homes without air-conditioning, as approximately one-thirdof residential units do not currently have access to air-conditioning and adding cooling
represents a significant opportunity to improve resident health and safety during
increasingly occurring extreme temperature events. The portion of households without©2022 Elevate Energy

4Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

air-conditioning is relatively consistent across Dane County geographies and heating
types.
b. Create a core program dedicated to electrifying residential buildings to scale
electrification of homes in Dane County. Because of ccASHP technology skepticism, lackof contractors, and relatively small incentives, a one-stop-shop approach that aligns
existing programs and resources available in Dane County is recommended.
c. Complete a similar study for homes heated by natural gas.
3. For ccASHP programs aimed at conversion of fuel-oil and propane heated residences, focus
initially on single-family housing stocks located in rural census tracts where this heating type isconcentrated. While fuel-oil and propane residences have higher simple paybacks and generally
lower carbon savings as compared to electric resistance homes, this housing stock is a key
segment outlined in the Dane County Climate Action Plan and important to not leave behind inelectrification efforts.

©2022 Elevate Energy

5Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Figures and Table List
FiguresFigure 1. Dane County PUMA Boundaries .................................................................................................... 8
Figure 2. Percentage Residences With Electric Heat by Census Tract ........................................................ 12
Figure 3. Percentage Residences With Propane Heat by Census Tract ...................................................... 12
Figure 4. Percentage Residences With Natural Gas Heat by Census Tract ................................................. 13
Figure 5. Distribution of Non-Natural Gas Heating Fuels for Dane County PUMAs ................................... 14
Figure 6. Census Tract Median Household Income Versus Percent of Units With Electric Heat ............... 15
Figure 7. Depiction of ducted split system heat pump with furnace.......................................................... 33
Figure 8. Depiction of a ductless mini-split heat pump system .................................................................. 33
Figure 9. Census tract median household income versus percent units with natural gas heat ................. 39
Figure 10. Census tract median household income versus percent units with propane heat ................... 40
Figure 11. Census tract median household income versus percent units with fuel-oil heat ..................... 40
TablesTable 1. Fuel Price Assumptions ................................................................................................................... 9
Table 2. Space Heating Fuels Across Dane County ..................................................................................... 11
Table 3. Top Five Most Common Housing and Heating System Pairs ........................................................ 13
Table 4. Pearson’s Correlation Test Results for Relationship Between Median Household Income andPrevalence of Space Heating Fuel Type ...................................................................................................... 15
Table 5. Utility Bill Savings for Five Most Common Housing and Heating Types (Per Unit Basis) .............. 16
Table 6. Utility Bill Savings for All Propane and Fuel-oil Systems (Per Unit Basis)...................................... 17
Table 7. Annual Carbon Savings for Five Most Common Housing and Heating Types (Per Unit Basis) ..... 18
Table 8. Annual Carbon Savings for All Propane and Fuel-oil Systems (Per Unit Basis) ............................. 19
Table 9. Aggregate Annual Carbon Savings Across Dane County By Housing Stock................................... 19
Table 10. Estimated Cost to Upgrade to ccASHP Per Unit Based On Existing Housing and Heating Type . 20
Table 11. Simple Payback Analysis .............................................................................................................. 20
Table 12. ccASHP Upgrade Cost Per Ton of Carbon Saved By Housing and Heating Type ......................... 21
Table 13. ccASHP Upgrade Cost by Housing and Heating System Type ..................................................... 34
Table 14. Emission Factor Inputs Into Carbon Analysis Models ................................................................. 36
Table 15. Full List of Housing and Heating Types in Dane County .............................................................. 37©2022 Elevate Energy

6Characterization of Cold Climate ASHPs in Dane County’s Residential Housing StockIntroduction
Decarbonization is a becoming a key strategy for many governments in combatting today’s climate crisis.
ASHPs (ASHPs) provide an efficient, all-electric way to both heat and cool homes using one system.
ASHPs are becoming a common recommended approach for many decarbonization strategies.
Previously ASHP technology had been limited to moderate climates 1; however, improvements in heatpump technology over recent years have enabled the development of ccASHPs (cold-climate ASHPs),
which can produce adequate heat even in extreme sub-zero temperatures. The purpose of this report isto quantify the potential for upgrading certain housing stocks in Dane County to ccASHPs and develop
strategies for accelerating ccASHP adoption in Dane County in existing homes that do not use natural
gas for heating.
Dane County has a broader 2020 Climate Action Plan (CAP), of which decarbonization is a key strategy tomeet the countywide goals of reducing greenhouse gas (GHG) emissions by 50% by 2030 in order tocarve a path toward carbon neutrality by 2050. The CAP is a living document with six guiding principles
that inform the recommendations to meet Dane County’s GHG emission goals, including: (1)equity/justice, (2) local economic benefit, (3) health benefits, (4) resiliency/security, (5) bridging theurban and rural divide, and (6) ecosystem benefits.
For Dane County to meet the 50% GHG reduction benchmark and eventual carbon neutrality laid out intheir CAP, significant changes must be made in energy consumption county-wide. Across Wisconsin, theresidential sector accounts for 24% of the state’s total energy consumption (EIA, 2019) and therefore
represents a significant opportunity for GHG reduction. This report focuses on the carbon savings
opportunity in electrifying the residential housing stock with ccASHPs.
In charting a path for 50% GHG reductions, Dane County identified about a dozen outcomes that, whencombined, reduce emissions in half. Several of those outcomes are about ASHPs; one outcome
identified in Dane County’s CAP is to transition half of the fuel-oil and propane heated homes to heatpumps by 2030, and all of homes with these heating fuels to heat pumps by 2045. Converting fuel-oil
and propane heated homes to ccASHPs can lower primary fuel use and is especially beneficial whencombined with on-site renewable energy sources such a solar. Furthermore, electrification can reinforce
the vision of equity, economic savings, wellness, and climate resiliency underscored in the CAP byimproving home comfort through cooling and removing potentially harmful toxics from the indoor air byeliminating the use of fossil fuel within the home. Despite ccASHPs’ ability to provide adequate heat incold climates, reduce carbon emissions, and increase access to cooling, uptake of ccASHPs in Wisconsin
has been low.
This report quantifies existing heating sources, evaluates the potential of ccASHP technology, gathers
stakeholder perspectives toward ccASHPs, and recommends best practices to accelerate installation ofccASHPs across Dane County. Our quantitative analysis examines ccASHP economic viability and how to

1

ASHPs are air conditioners that can run in reverse. In cooling mode, the ASHP cools the inside of the home andmoves the heat to the outside, just as a standard air conditioner does. In heating mode, the inside heat exchanger
and outside heat exchanger effectively change roles; the ASHP cools the outside and moves the heat to the insideof the home. ccASHPs are specially designed to operate at colder outside temperatures than standard ASHPs.

©2022 Elevate Energy

7Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stockprioritize varying housing stocks. The qualitative analysis identifies obstacles and motivators in
implementation, as well as gathered perceptions to inform messaging.

Approach and Methodology
The scope of this analysis includes space heating in residences that do not use natural gas across DaneCounty. The building stock across Dane County is diverse and requires varied approaches for ccASHP
retrofits; our goal is to identify niches within the scope in order to target ccASHP implementation
programs that can best help Dane County reach its carbon savings goals. Our approach is two-fold: (1)quantify the Dane County building stock to identify target segments and quantify the carbon, utility, andcost impact of ccASHPs used for space heating in such segments, and (2) collect qualitative data on theexperiences of homeowners and building owners with or considering ccASHP technologies. This section
includes a description of our methodology, assumptions, and limitations for each approach is described.
A more detailed description of the methodologies used in this report is included in Appendix A.

Quantitative Analysis Methodology
The primary data source for the analysis is the National Renewable Energy Laboratory’s (NREL)
ResStockTM data tool. ResStockTM has representative residential building stock information throughout
the United States and uses the American Community Survey (ACS) and American Housing Survey (AHS)
data at the Public Use Microdata Area (PUMA) level, along with other datasets, to create a database ofrepresentative buildings. PUMA geographies represent statistical geography areas defined by the U.S.
Census, which are non-overlapping areas with a population of at least 100,000 people. Dane County
consists of three PUMA boundary areas (Figure 1): City of Madison (PUMA 101), East Dane County(PUMA 102), and West Dane County (PUMA 103). From a housing development perspective, PUMAs 102
and 103 are more rural compared to the PUMA 101, which is located within the city limits of Madison.
Figure 1. Dane County PUMA Boundaries

The ResStockTM database used for this analysis contains approximately 20,000 residential units
statistically sampled to be representative of the Dane County building stock. Data points include
detailed building characteristics for each residential unit (e.g., square footage, heating system type,©2022 Elevate Energy

8Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stockheating system efficiency) and annual baseline energy use by end-use and fuel (e.g., heating fanelectricity consumption, heating propane energy consumption). These data points are used in our
analysis to characterize the Dane County housing stock and estimate energy savings from
implementation of ccASHPs. Additional information on the ResStockTM database and assumptions about
the database used for this analysis can be found in Appendix A.
Energy savings estimates are calculated by applying engineering calculations to the baseline energy use
obtained through the ResStockTM database. The lifetime of the ccASHP was assumed to be 20 years.
Utility bill savings are calculated using average fuel rates (Table 1). Each rate is multiplied by theestimated energy use by fuel type before and after the ccASHP retrofit. Details on the methodology forthese calculations can be referred to in Appendix A.
Table 1. Fuel Price Assumptions
Fuel

Price

SourceElectricity$0.12 per kWhMadison Gas & Electric,
Wisconsin Power & Light 2

Propane$1.55 per gallon

EIA – Wisconsin 5-year average

Fuel-oil$2.33 per gallon

EIA – Wisconsin 5-year average

For our upgrade cost estimates, if a unit’s existing heating system already has ducts (e.g., a central
furnace), a ducted heat pump air handler with electric resistance supplemental heat is proposed. The
existing duct system is assumed to be adequate. If a unit’s existing heating system does not haveductwork (e.g., electric baseboard heat), a ductless mini-split heat pump system is proposed withmultiple heads. The primary source for cost information is RSMeans with a location of Madison, WI.
However, we did compare costs obtained through RSMeans with other data sources such as contractor
quotes obtained by Elevate for similar install work ongoing in Wisconsin and a recently publishedWisconsin-specific report on ccASHP costs (Center for Energy and Environment, 2021). Details of the
proposed ccASHP system based on the existing heating system and items included in the cost estimates
can be found in Appendix A.
Energy savings are converted to carbon savings under two different future grid scenarios using NREL’s
Cambium tool. The two scenarios are as follows:••2

Business-As-Usual: Also referred to as Mid-Case by NREL, this scenario uses current policies anddefault or mid-level assumptions to generate a reference case. This scenario reflects changes in
the grid over time, but only changes that flow from the current business-as-usual factors andpolicies.
Low Renewable Cost: This scenario is modeled using low costs for renewable energy, therefore
increasing the share of renewables on the grid compared to other sources. Unlike business-asusual, this scenario reflects shifts in the factors that influence the fuel mix of the grid. Both
Madison Gas & Electric and Alliant Energy have clean electricity goals to substantially reduce

The average electric rate was calculated for the major electric utilities in Dane County©2022 Elevate Energy

9Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stockcarbon emissions in the coming decades. 3 Given the likely policy and subsidy changes on thehorizon, we feel this low-renewables cost scenario is a very likely and reasonable future model
to use.
A detailed description of the rationale behind these two scenarios can be found in Appendix A.

Interview Methodology
Interviews were conducted with various stakeholders who have considered or already installed ASHPs in
Dane County to gather feedback on their experience with this in Wisconsin and help contextualize ourquantitative findings as part of the data analysis. Municipalities were also engaged in interviews tounderstand their perspectives and outlook on ASHP programs.
Sustain Dane led recruitment of interviewees. Sustain Dane has a wide breadth and depth of individuals
and organizations that they work with on sustainability issues across Dane County. Emails were sent
individually to 40 people, asking if they or someone in an organization that they are a part of would beinterested in being interviewed. The recipients of outreach emails included local business leaders, nonprofit and religious organizations, municipal staff and leaders, vendors of ASHPs, energy sector
representatives, and building owners in the multi-family sector working with the Sustain Dane andElevate Efficiency Navigator program. Many of the contacts further expanded our outreach throughtheir networks as well. For example, we asked a Green Team church representative to share interview
information with their entire congregation. An example of the recruitment outreach flyer can be foundin Appendix D.
Sustain Dane also promoted the project and request for interviewees in their June 2021 electronic
newsletter and on social media platforms. The notification about interviewer recruitment highlighted
that we were seeking candidates that aligned with a research focus of either: (1) single-family(detached) housing with propane fuel, electric baseboard, or electric furnace heat; or (2) multi-family(5+ units) housing with electric baseboards, electric shared heating, or electric furnace heat. Interviews
were estimated to take 30 minutes and all participants were entered to win a $200 visa gift certificate.
Interviewees reached out from all three approaches (i.e., emails, the newsletter, and social media).
Ultimately, we conducted 14 interviews.
We acknowledge that there are limitations with the use of the interview information. The feedback
collected is a small sample and cannot be considered representative across an entire sector.
Interviewees were self-nominated/self-selected, and already had an interest in or connection with
ASHPs prior to the interview. The interviewees also represented a wide variety of sectors, including
homeowners, building managers, ASHP representatives, and municipalities. Interviews were conducted
for 30 minutes via Zoom, which is a short amount of time to gather the full extent of the interviewee’s
perspective on ASHPs. That being said, the interviews were highly informative as case studies. They
brought to the forefront lived experiences, perceptions of opportunities and challenges, andconsiderations for future education and/or incentive program implementation.

https://www.mge.com/net-zero-carbon-electricity;
https://www.alliantenergy.com/cleanenergy/ourenergyvision/responsibilityreport/cleanenergyvisiongoals?utm_s
ource=WS&utm_campaign=Legacy&utm_medium=AboutAlliantEnergy/ResponsibilityReport/CleanEnergyVisionGoals
3©2022 Elevate Energy

10Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Data Analysis Results
Dane County Housing Stock and Heating Fuels
According to the ResStockTM database, Dane County has 239,800 residential units as of 2018. 4 As
mentioned, the focus of this report is housing in Dane County not heated with natural gas. Roughly twothirds of those units are heated with natural gas (Table 2). Non-natural gas units are predominantly
heated with electricity (25% of units) or propane (5% of units).
Table 2. Space Heating Fuels Across Dane County
Space Heating Fuel

Total Residential
Units

Percent of Housing
Stock

Natural Gas

158,844

66%

Electricity

59,75825%

12,769

5%

4,868

2%

Fuel-oil

2,074

1%

None

1,487

1%

Dane County Total

239,800

100%

PropaneOther Fuel

5

In Figures 2-4, the percentage of electric, propane, and natural gas heat for each census tract is mapped
across Dane County. Census tracts with darker colors indicate a higher portion of the residences in that
census tract use the specified type of heat. For context, municipalities in Dane County are outlined inblack and labeled. As expected, census tracts in more rural areas tend to have propane space heating(Figure 3). Census tracts in more urban areas tended to have electric space heating (Figure 2). Of note,the data used in these maps is from the ACS 6 and is not used in the energy or carbon savings analysis.
This is because while ACS offers high spatial granularity, ResStockTM offers higher granularity withregards to the housing characteristics, systems, and energy use.

Residential unit refers to a single-family home, a multi-family unit, or a mobile home.
Other Fuel includes the following heating types: wood, coal, solar, and other.
6
ACS 2019 5-year estimates
45©2022 Elevate Energy

11Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Figure 2. Percentage Residences With Electric Heat by Census Tract

Figure 3. Percentage Residences With Propane Heat by Census Tract©2022 Elevate Energy

12Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Figure 4. Percentage Residences With Natural Gas Heat by Census Tract

The attributes of housing stock were also assessed using the ResStockTM database, as the housing
characteristics impact the ccASHP implementation approach. Of the 80,944 residential units not heatedwith natural gas (34% of the total housing stock in the ResStock dataset), the top five most frequent
housing type and heating system pairs in Dane County were identified in order to focus the analysis on
the most common building stock. These top five most common housing/heating pairs are in Table 3; acomplete list of housing types and heating systems can be found in the Appendix B. Notably, four of the
top five most common systems within the dominant housing types have electric heat.
Table 3. Top Five Most Common Housing and Heating System Pairs
Percent of NonNatural Gas
Housing Stock

Housing TypeSpace Heating System

Total Residential
Units

Multi-family (5+ Units)

Electricity Baseboard

24,24430%

Multi-family (5+ Units)

Electricity Electric Furnace

9,688

12%

Single-family (Detached)

Propane Fuel Furnace

7,482

9%

Single-family (Detached)Electricity Baseboard

5,324

7%

Single-family (Detached)Electricity Electric Furnace

4,053

5%

50,79063%

Total

Electric resistance-based heating represents a sizable portion of the space heating market and therefore
potential opportunity for large carbon savings. Across the three PUMAs in Dane County (refer to Figure1), electric resistance heat is the most common non-natural gas heating source in all three PUMAs(Figure 5). Electric resistance heating makes up 85%, 65%, and 75% of the non-natural gas building stock©2022 Elevate Energy

13Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stockheating in Madison, East Dane County, and West Dane County, respectively. Propane heating is morecommon in the East and West Dane County PUMAs compared to Madison, while the frequency of fueloil heating is consistent across all three PUMAs (~3% of non-natural gas heating).
Figure 5. Distribution of Non-Natural Gas Heating Fuels for Dane County PUMAs

Madison PUMA (101)East Dane County PUMA (102)3%

Propane7% 6%

Fuel Oil

Fuel OilElectric

Electric

Other Fuel

8%

16%

2%

PropaneFuel OilElectric

Electric
74%

65%

Dane County, WI

Fuel Oil
Other Fuel

23%
3%

Other Fuel85%

West Dane County PUMA (103)Propane9%

PropaneOther Fuel

8%

16%

3%

74%

A brief socioeconomic analysis was conducted to evaluate the relationship between prevalence ofelectric space heating and income level in Dane County. A 2021 statewide study across Wisconsin
documented multi-family housing as having a higher proportion of electric heat and residents who are
low-income (Center for Energy and Environment, 2021). A Minnesota study also found that householdswith lower incomes were more likely to have electric resistance heating (CARD, 2018). Across DaneCounty, Figure 6 shows the median household income versus the percentage of units with electric spaceheat by Census Tract. The Pearson’s correlation test was used to examine the linear correlation between©2022 Elevate Energy

14Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stockincome and prevalence of space heating fuel types. The correlation coefficient and significance for thePearson’s correlation tests are shown in Table 4. Lower median incomes were significantly associatedwith a higher prevalence of electric space heating at the census tract level (p-value <0.001). A significant
positive relationship between natural gas and higher incomes was also noted (p-value < 0.001). The
correlation between propane and income was not evaluated as their relationship is visibly non-linear
and therefore testing the linear relationship is not appropriate (see propane graph in Appendix C). Fueloil did not have a significant relationship with income. The association found between lower incomesand electric resistance space heating indicates that implementing ccASHPs in units with electric heat
may help target communities with lower incomes that could benefit the most from cost savings fromhigh efficiency heat pump heating.

Percent Units within a Census Tractwith Electric Heat

Figure 6. Census Tract Median Household Income Versus Percent of Units With Electric Heat
60%
50%
40%
30%
20%
10%
0%

$0

$40,000$80,000$120,000$160,000$200,000Median Household Income (2019)

Table 4. Pearson’s Correlation Test Results for Relationship Between Median Household Income andPrevalence of Space Heating Fuel TypeSpace Heating Fuel

Correlation
Coefficient 7

P-valueElectric-0.58

5.834e-11***Natural Gas

0.37

0.0001218***

Fuel-oil

0.07

0.4544

Interpretation
Significant negative association
between prevalence of electric heatand income
Significant positive association
between prevalence of natural gas
heat and income
No significant association*p-value < 0.05, **p-value < 0.01, ***p-value < 0.001
We caution against using the magnitude of the reported coefficient in the interpretation of the results since
additional variables are not accounted for; instead, the application of this significance test in our study is primarily
to examine the directionality of the relationship (i.e., positive or negative).

7©2022 Elevate Energy

15

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Because of the prominence of electric resistance heating, and the focus of the Dane County Climate
Action Plan on propane and fuel-oil heating, the savings analysis includes an examination of propane,fuel-oil, and electric resistance space heating.

Savings Analysis – Utility Bill and Carbon Savings
The following sections detail the utility and carbon savings associated with implementation of ccASHPs
in Dane County.
UTILITY SAVINGS PER UNIT
In Table 5, the average heating, cooling, total, and percent utility savings are shown on an average perunit basis. Results are broken down by units with an existing air conditioning system (including both
central and window air-condition) and units with no previous air-conditioning. The average annual
heating bill savings for multi-family buildings with electric baseboard heat and existing air conditioning is$449 per unit. These savings represent averages across the Dane County building stock and will vary
based on specific housing conditions. Overall, residences with electric resistance heat are expected tosave about half on their combined utilities spent on heating and cooling (see “Percent Heating/CoolingUtility Bill Savings”). Utility savings are slightly lower for homes that are paying for air conditioning with
a ccASHP when they previously did not have access to air conditioning. Added cooling costs range on
average from $40 to $108 per year, however, the overall average annual cost savings is still net positive
across all housing types (see “Average Annual Cost Savings”). The larger savings realized by single-family
homes is due to the high heating energy consumption of single-family homes with high thermal loss
through the building envelope (as compared to multi-family units).
Table 5. Utility Bill Savings for Five Most Common Housing and Heating Types (Per Unit Basis)

Total
Units

AverageAnnualHeating Bill
Savings

AverageAnnualCoolingBill
Savings

AverageAnnualCost
Savings

Percent
Heating/Cooling Utility
Bill Savings

MF 5+: Electric Baseboards

15,875

$449

$22

$471

50%

MF 5+: Electric Furnace

5,084

$378

$14

$392

51%

SF Detached: Electric Baseboards

3,225$1,145$30$1,17550%

SF Detached: Electric Furnace
SF Detached: Propane Fuel
Furnaces
Units without air conditioning

3,585$1,302$36$1,338

52%

6,199

$359

$36

$395

22%

MF 5+: Electric Baseboards

8,369

$450

-$58

$392

46%

MF 5+: Electric Furnace

4,604

$376

-$40

$336

48%

SF Detached: Electric Baseboards

2,074$1,130-$81$1,04948%

SF Detached: Electric Furnace
SF Detached: Propane Fuel
Furnaces468$1,364-$108$1,256

49%

1,259

$359

-$107

$251

15%

Heating Fuel

Units with existing air conditioning©2022 Elevate Energy

16Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Homes with propane or fuel-oil are expected to save 18-24% on their heating and cooling costs (Table
6). Average annual utility bill savings are slightly more for fuel-oil ($342-$476 per year) than propane($310-$413 per year). These utility savings estimates represent averages across the building stock andare sensitive to price fluctuations in the propane and fuel-oil markets. Actual savings will vary based on
individual building characteristics and fuel prices. Absolute cost savings are slightly higher in homes
presently using fuel-oil for heat, primarily driven by the higher baseline heating energy for fuel-oil
homes.
Table 6 summarizes the average utility savings across all propane and fuel-oil systems, including both
single-family and multi-family housing stocks. These results were not disaggregated by housing type as
the vast majority of residences heated with fuel-oil and propane are in the single-family housing stock.
Table 6. Utility Bill Savings for All Propane and Fuel-oil Systems (Per Unit Basis)
AverageAnnualHeatingBill
Savings

AverageAnnualCooling Bill
Savings

AverageAnnualCost
Savings

Percent
Heating/CoolingUtility Bill
Savings

Units with existing air conditioning (all housing types)
Propane
9,256
$380

$32

$413

24%

Fuel-oil

$442

$34

$476

24%

Heating Fuel

Total
Units

1,499

Units without air conditioning (all housing types)
Propane

3,489

$395

-$84

$310

20%

Fuel-oil

576

$434

-$93

$342

18%

If all homes in this analysis were converted to ccASHPs, Dane County residents, in aggregate, would saveover $31 million dollars in utility costs annually.
CARBON SAVINGS PER UNIT
In an analysis of the five most common housing and heating system types in Dane County, the highest
carbon savings on a per unit basis are single-family homes with electric baseboard or furnace heating
systems (Table 7). Under the business-as-usual case, an average of 4.6 tons of carbon is expected to be
saved annually for single-family homes with electric baseboard, and 5.2 tons of carbon for single-family
homes with electric furnaces. The per unit carbon savings decrease to 4.1 and 4.9 tons, respectively, if ahome did not already have air conditioning, because of the additional carbon emissions from adding air
conditioning. Overall, for electric heating systems, heating and cooling carbon emissions is expected tobe reduced by about 50%. This corresponds to a total home energy reduction between 26-36%.
Under the business-as-usual scenario, single-family propane furnaces have the lowest absolute andpercentage carbon savings; however, the carbon savings almost double under the low renewable cost
scenario. This is due to the electricity grid having a higher percentage of renewable energy supply in the
low renewable energy cost scenario; thus, for conversion of fuel heating systems, the carbon savings will
increase under the low renewable energy cost scenario. For residences heated with electric heat,absolute carbon savings are reduced under the low renewable energy cost scenario because the heating©2022 Elevate Energy

17Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stockfuel before ccASHP implementation is also electric and will have the same carbon savings under acleaner grid. Across all residences, carbon savings in homes that originally did not have air conditioning
is lower than residences that already had air conditioning. On average, the carbon savings for homes
without air conditioning is on average 6-17% lower than homes already with air conditioning.
Table 7. Annual Carbon Savings for Five Most Common Housing and Heating Types (Per Unit Basis)
Annual Carbon
Savings (Tons/Unit)

Percent
Heating/Cooling
Carbon Savings

Percent Total Unit
Carbon Savings

Businessas-usual 8

Low RE
cost 9Businessas-usual

Low RE
cost

Businessas-usual

Low RE
cost

MF 5+: Electric Baseboards

1.8

1.4

50%

50%

29%

29%

MF 5+: Electric Furnace

1.5

1.2

51%

51%

26%

26%

SF Detached: Electric Baseboards

4.6

3.5

50%

50%

34%

34%

SF Detached: Electric Furnace
SF Detached: Propane Fuel
Furnaces
Units without air conditioning

5.2

4.0

52%

52%

36%

36%

1.3

2.4

19%

36%

11%

24%

MF 5+: Electric Baseboards

1.5

1.2

46%

46%

26%

26%

MF 5+: Electric Furnace

1.3

1.0

48%

48%

26%

26%

SF Detached: Electric Baseboards

4.1

3.1

48%

48%

31%

30%

SF Detached: Electric Furnace
SF Detached: Propane Fuel
Furnaces

4.9

3.7

49%

49%

33%

32%

0.7

2.0

11%

32%

6%

19%

Housing/Heating System Type

Units with existing air conditioning

A similar analysis was conducted for all propane and fuel-oil homes across Dane County. A key objectiveof the Dane County Climate Action Plan is transitioning half of the fuel-oil and propane homes to heatpumps by 2030, and all of homes using these heating fuels to heat pumps by 2045. According to the
ResStockTM housing totals, this would involve converting 6,385 propane homes and 1,037 fuel-oil homesby 2030, and the same number of homes by 2045. Under the business-as-usual scenario, converting
propane heated homes to ccASHPs is projected to save between 1.0-1.4 tons of carbon per unit annuallydepending on if the homes already have air conditioning (Table 8). This represents a 17-21% heating andcooling carbon savings, and 10-13% on total home carbon emissions. Absolute and percent carbon
savings increase under the low renewable energy scenario because of the added carbon savings post-

Also referred to as Mid-Case by NREL, this scenario uses current policies and default or mid-level assumptions togenerate a reference case. This scenario reflects changes in the grid over time, but only changes that flow from thecurrent business-as-usual factors and policies.
9This scenario is modeled using low prices for renewable energy, therefore increasing the share of renewables on
the grid compared to other sources. Unlike business-as-usual, this scenario reflects shifts in the factors that
influence the fuel mix of the grid. Given the likely policy and subsidy changes on the horizon, we feel this lowrenewables cost scenario is a very likely and reasonable future model to use.
8©2022 Elevate Energy

18Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stockelectrification due to an electric grid with more renewable energy. Trends are similar for fuel-oil homes;
however, fuel-oil has a higher absolute carbon savings compared to propane.
Table 8. Annual Carbon Savings for All Propane and Fuel-oil Systems (Per Unit Basis)
Housing/Heating System Type

Annual Carbon
Savings (Tons/Unit)

Percent
Heating/Cooling
Carbon Savings

Percent Total Unit
Carbon Savings

Businessas-usual

Businessas-usual

Low RE
cost

Businessas-usual

Low RE
cost

Low RE
cost

Units with existing air conditioning (all housing types)
Propane

1.4

2.4

21%

38%

13%

24%

Fuel-oil

2.7

3.9

31%

46%

21%

34%

Units without air conditioning (all housing types)
Propane

1.0

2.1

19%

38%

12%

25%

Fuel-oil

2.2

3.5

28%

45%

19%

32%

TOTAL ANNUAL CARBON SAVINGS ACROSS DANE COUNTY
The following analyses aggregate the per unit results to estimate the potential for carbon savings if allresidential units under a specific housing type are upgraded with ccASHPs. Summing up across DaneCounty, Table 9 shows the annual carbon impact of retrofitting select building stocks across DaneCounty to ccASHPs. Depending on the carbon scenario modeled, tons of carbon saved range from 115120 thousand tons annually. This corresponds to an average heating/cooling carbon savings ranging
from 11-52% and an average total housing carbon savings from 6-36%, depending on the specifichousing stock.
Table 9. Aggregate Annual Carbon Savings Across Dane County By Housing Stock 10
Scenario

Total
Units

Total Annual Carbon Savings (Tons CO2)
Business-as-usual

Low RE cost

Multi-family 5+: electric resistance

33,93255,00040,000Single-family (detached): electric resistance

9,352

45,00035,000All housing types: propane

12,76915,00030,000All housing types: fuel-oil

2,074

5,000

10,000

Total

58,127

120,000

115,000

10

Results are rounded to the nearest 5,000©2022 Elevate Energy

19Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Air Source Heat Pump Upgrade Cost Analysis
This section details the estimated cost to upgrade a residential unit to a ccASHP in Dane County. Per unit
costs are discussed first followed by aggregated costs across Dane County.
UPGRADE COST PER UNIT
Of the top five most common systems, we estimate the least expensive heating systems to upgrade areelectric baseboard systems in multi-family buildings, at a cost of $8,500 per unit (Table 10). Cost
assumptions for housing type and heating system pairs can be found in the Appendix A. Generally, thelower cost of the multi-family baseboard system is driven by the assumption that this retrofit will
involve two mini-split heads, versus three assumed in the single-family home. Also, we assume furnace
upgrades will require removal of the existing furnace while electric baseboards are left in place. Propane
system replacements are the highest to replace, totaling to $16,500 per unit, and this cost includes both
existing furnace removal and the added electrical capacity. All ccASHP retrofit cost estimates include thecost of backup electric resistance heating.
Table 10. Estimated Cost to Upgrade to ccASHP Per Unit Based On Existing Housing and Heating Type
Housing and Heating Type

Average Cost to Upgrade
to ccASHP Per Unit

MF 5+: Electric Baseboards$8,500

MF 5+: Electric Furnace$11,500

SF Detached: Electric Baseboards$13,000

SF Detached: Electric Furnace$11,500

SF Detached: Propane Fuel Furnaces$16,500

COST TO IMPLEMENT VERSUS UTILITY SAVINGS
The per unit cost to implement ccASHPs and per unit utility savings were aggregated across all buildings
within specific housing stocks. The lowest simple payback across housing stocks considered is the singlefamily electric resistance housing stock, with an average simple payback of 10 years (Table 11). Propane
and fuel residences have the highest simple payback, at 41 and 37 years, respectively. Multi-family
electric resistance falls in the middle, with a payback of 23 years. These paybacks, particularly in homes
using fuel-oil or propane, are a significant barrier to most residents interested in ccASHPs. In the shortterm, financial incentives or rebates will be necessary to encourage owners to adopt higher efficiency
heating alternatives, such as ccASHPs.
Table 11. Simple Payback Analysis$321,980,000

Total Annual
Utility
Savings$14,300,000

SimplePayback(Years)23

9,352$115,620,000$11,350,000

10

12,769$202,770,000$4,900,000

41

2,074

$33,330,000$910,000

37

Total
Units

Total Upgrade
Cost

Multi-family 5+: electric resistanceSingle-family (detached): electric
resistance
All housing types: propane

33,932All housing types: fuel-oil

Housing Stock©2022 Elevate Energy

20Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

COST TO IMPLEMENT PER TON OF CARBON SAVED
Comparing the total upgrade cost per ton of carbon saved over the lifetime of the ASHP can be a usefulway to compare the economics of different building segment scenarios and help prioritize cost effective
housing segments for ccASHP programs. The upgrade cost per lifetime ton of carbon saved is presented
for both the business-as-usual and low renewable energy cost grid scenarios in Table 12. Under thebusiness-as-usual carbon scenario, single-family homes with electric resistance heat are the mosteconomical (in terms of upgrade cost per ton of carbon saved) to upgrade to ccASHPs ($131/ton saved).
Multi-family units with electric resistance ($290/ton saved) and fuel-oil homes ($312/ton saved) are thenext most economical. Under the low renewable energy cost scenario (i.e., a grid with a higher
proportion of renewables) single-family homes with electric resistance heat still have the lowest cost($172/ton saved), followed by fuel-oil homes ($211/ton saved). From this lens, single-family electric
resistance systems are the most cost efficient across all the target housing segments to convert to
ccASHPs.
Table 12. ccASHP Upgrade Cost Per Ton of Carbon Saved By Housing and Heating Type
Housing and Heating Type Scenario

Total Units

Carbon Scenario($/Lifetime Tons Carbon
Saved) 11
Business-as-usual

Low RE cost

Multi-family 5+: electric resistance

33,932$290$381

Single-family (detached): electric resistance

9,352

$131

$172

All housing types: propane

12,769$640$348

All housing types: fuel-oil

2,074

$312

$211

The data analysis results quantify the potential benefits and costs associated with implementing
ccASHPs across specific housing stocks in Dane County. The following section details the interview
results on key housing segments identified and adds greater context to homeowner decisions around
ccASHPs in Dane County.

11

The lifetime of the ccASHP is assumed to be 20 years©2022 Elevate Energy

21Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Interview Results
Elevate and Sustain Dane held 14 interviews over the course of June, July, and August 2021. Eachinterview lasted 30 minutes on average. Five single-family homeowners, four municipality contacts in
Dane County, three multi-family property owners/managers, and two utility sector contacts wereinterviewed. Of the eight homeowners and multi-family property owners, three had electric resistanceheating, two had natural gas alone and were considering an ASHP, and one had a combined propane
and natural gas system. There were also two interviewees whose homes already ran on ASHPs. One
ASHP’s backup heating system was natural gas and the other backup system used fuel-oil.
The following section contains overall themes from the interviews and is followed by two case studies
focusing on propane heating in single-family homes and electric resistance heating in multi-family
homes. Both case studies present situations where the owner opted to not to install ASHPs, thus
highlighting challenges ASHP implementation programs may face in Dane County. We also selected
these case studies as they contain major themes noted throughout many interviews and represent
opportune housing stocks identified in the data analysis.

Themes From Interviews
Lower energy costs and carbon emissions are top of mind.
Reducing energy costs and carbon emissions were at the forefront of motivating factors for all
interviews. Secondary motivating factors were comfort, extending the life of an existing heating system,and the ease of heating and cooling combined in one system. Comfort was especially pertinent tointerviewees who did not already have air conditioning or those whose electric resistance heating did
not keep them warm in the winter.
Interviewees who installed an ASHP have a positive opinion.
We interviewed two single-family homeowners who already had ASHPs running in their houses. Bothwere extraordinarily pleased with their ASHPs, especially the homeowner who had hers the longest. As
an extremely energy-conscious homeowner, she had completely upgraded all appliances to the highest
efficiency possible with the assistance of a Green Mortgage refinance. She had her ASHP installed in2008 by a contractor from out-of-state because there was no one in Wisconsin at the time who wasfamiliar with the technology. The house previously only had an old gas furnace that needed to be
replaced. The homeowner kept it as a back-up heating system and was amazed that the ASHP extended
the life of the furnace tremendously. Because the ASHP was doing the bulk of the heating, the gas
furnace barely had to run at all. As a result, it lasted years beyond what was anticipated when it was the
only heating system. The homeowner considered not having to buy a new gas furnace as additional costsavings. She was impressed that the ASHP had reduced energy use and costs by around 20%, according
to her estimations. She shared her positive experience with other friends and acquaintances, who she
said also ended up installing ASHPs in their homes at her recommendation. When she moved in 2018,
she went on to buy the house of someone who had an ASHP installed in it because of her.
A condo manager initially thought she had no background knowledge of ASHPs, but later recalled that
one resident had gotten approval from the condo board to convert to an ASHP. The condo ownerdemonstrated impressive initiative and left an overall positive impression of ASHPs on the managementcompany.

©2022 Elevate Energy

22Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Interviewees who opted to not install an ASHP are uncertain without additional information.
Early adopter questions were a common theme, which was reflective of our interview sample. The costfeasibility, accessibility, and reliability of the technology were all discussed. A single-family homeownerfelt like she could not move forward without hearing someone’s firsthand account of the reality of
having an ASHP. Through her research online, she found the information available on ASHPs was sparse,
often hypothetical, and not specific to Wisconsin, so there was a degree of doubt amongst interviewees
about real-world application. Beyond the need for a general public information campaign, questions
about utility bill costs when fuel-switching lingered. Interviewees reported difficulty with finding a
breakdown of prospective operating costs for homeowners while researching ASHPs, and ASHP
incentives were not high enough to overcome the questions of upfront costs. Naturally, even those who
are willing to pay a price premium for decarbonization are hesitant. “Everyone wants to know if theyshould wait a few years until it’s standardized,” concluded a municipal contact.
A couple interviewees, both single-family and multi-family owners, expressed long-term concerns
influencing their outlook on ASHPs. They would be more eager to invest in the upfront cost if they could
be assured it could increase property value. The single-family homeowner had ultimately not sprung for
the ASHP yet, partly because of the inconvenience and inaccessibility in the process, as well as the factthat “This isn’t our forever home. I’m not sure a buyer will see the value.”
Opportunities for environmental justice should be considered.
From a municipality perspective, one municipal contact reminded us that environmental justice will beat the forefront of electrification. “Right now [incentives] are probably not high enough to push the
majority of consumers over the edge. The people who could benefit the most from the cost savings are
the ones who couldn’t afford the upgrade at all.” Their conclusion was that 50-100% of costs should becovered for low-income housing. Municipalities also saw natural disasters as an avenue of opportunity
for electrification. When Dane County was subjected to record-breaking flooding in 2018, many home
appliances were damaged beyond repair and there was a widespread surge of upgrades needed indamaged buildings. Their thinking was these needed upgrades presented an opportunity to fund more
efficient replacements as part of the recovery effort. There is the added benefit of not creating waste
when providing ASHPs in this scenario since the replacements would be necessary.

Case Study 1: Single Family Homeowner with a Propane Heating System
We spoke with a single-family homeowner who, much like the rest of his township, used a propane
heating system. Occasionally the homeowner also heated with wood. The homeowner had concerns
both about utility bill costs and reducing his carbon footprint. While the homeowner believed that
propane would be less expensive than other heating sources, he also observed that his energy bills werehigher than he anticipated. The homeowner was also environmentally conscious and had taken steps tomitigate energy consumption through conscious energy use. Saving energy was as important, if not
more, as cutting costs to him. Although his home had a central air conditioning system, he estimated heonly used it about five days a year. To reduce energy consumption, he set his thermostat low in thewinter and high in the summer.
Due to high energy bills and a desire to reduce his carbon footprint, this interviewee conducted researchon more efficient heating systems. He focused at first on geothermal energy as he had already heard
this form of heating was more efficient. Through this research, he discovered the additional option ofheating his home with an ASHP. The homeowner became interested in electrifying space heating with a©2022 Elevate Energy

23

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stockheat pump upon the realization that it would be a more affordable option than a geothermal heatpump. The idea of streamlining his HVAC system with an ASHP was something that also greatly appealed
to the homeowner. He was attracted by the idea of having heating and cooling all in one system. The
homeowner stated that he would likely consider paying more for an all-in-one system.
In the end, however, he decided not to pursue an ASHP for space heating for several reasons. One of thehomeowners most significant hang-ups when evaluating an ASHP system was the need to continue
maintaining the propane system since both would be required in the dual-fuel propane system thehomeowner was considering. Although most interviewees found comfort in having a back-up heater for
the winter, this homeowner worried that if he was using the heat pump almost exclusively, he would
forget to have enough propane on hand on the coldest days of the year. “I don’t want to forget tomaintain my [propane] furnace until when I need it the most,” he stated. He also spoke about hearingthat ASHPs produce a "gentle heat" that would not keep him as warm. Regarding maintenance, hespoke about not feeling comfortable that there were such limited options for contractors who could
service an ASHP after installation. A previous negative experience with a contractor further raised hisconcern since a negative interaction with the only ASHP contractor available could leave him without
any contractor to maintain his system. Maintenance with the propane system was minimal; he had only
needed one repair on the propane heater in the past.
The convenience of using propane, the system he was already familiar with, was also a reoccurring
theme in our discussion. He had a favorable view of his propane supplier, which predicts when and how
much propane he'll need annually based on historic use, and then delivers it to his door. It took theguesswork out of the equation for the homeowner, and he was fond of having a prepaid winter heatingbill. Having a system he was already familiar with gave him peace of mind.
Without a full cost parity to inform his decision, the homeowner fell back on his belief that switchingfrom propane to an ASHP would not save on his energy bills. Given the priority he placed on savings,
rebates and incentives could have motivated him to switch. Additional warranties and options forassistance with installation or repairs from multiple contractors were other resources that would
significantly alleviate the homeowner's hesitancy. He was well informed on the reality of ASHPs despite
not knowing anyone who had firsthand experience with one. Nonetheless, he still had questions ofpracticality and when would be the right time to make the switch.

Case Study 2: Multi-family Owner With Electric Baseboard Heat
We spoke with a multi-family property owner who managed a substantial number of apartmentbuildings. The complexes our discussions focused on were between 7-26 units and used electric
resistance heating. The electric baseboards were all recently updated and controlled digitally through aremote thermostat on an app. The property owner did his best to educate residents on saving energy,
even though it the tenants pay for their electric utilities. He stated that electric resistance heating"deserves a little bit of its bad reputation" but costs were manageable with proper resident education
and usage. He commented that other property owners who cover utilities for tenants tended to increase
rent by approximately $50 to cover the utility costs for studio and one-bedroom apartments.
The property owner wanted to minimize his and his residents' carbon footprint so long as it was
economically feasible. He initially explored solar energy but decided against it due to the payback period
being double what he expected at 12 years, instead of 6 years (his preference). Moreover, when he had©2022 Elevate Energy

24Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

his properties assessed, his larger buildings did not have preferable orientation for solar and the solar
company discouraged him from installing solar on his smaller buildings. This interview was the only one
where the property owner questioned the effect energy efficiency upgrades would have on curb appealof his property, which was important to him.
The property owner was somewhat familiar with ASHPs. He wasn't aware of cold-climate heat pumps
and doubted the capability of ASHPs to perform well in low temperatures. Consequently, the property
owner was under the impression that ASHPs "didn't have a good application in Wisconsin." Nonetheless,he acknowledged that the technology may have improved in the years since he first looked into ASHPs.
A deciding factor in the property owner's inaction to acquire a heat pump was the availability and easeof installation. The property owner did not want to struggle to find a contractor who would be able tomaintain the ASHP and do repairs. “I wouldn’t know who to call. It can’t be too complicated.” was his
worry. Typically, any work with contractors – heat pump or otherwise – also was complicated by theturn around period for him. The property owner felt it was often a challenge to complete upgrades
during the short timeframe of vacancies without significant upfront research and planning.
Yet another hurdle for the property owner was incentives, which he frequently referred to as a "way too
much of a hassle." He relied solely on his contractors to find incentives for him, and even to assist him
with the application. The property owner had received some incentives in the past, but claimed he had"discouraging" experiences and had "given up" since then – unless the contractor intervened to apply
themselves or made it exceptionally easy for him to apply.

©2022 Elevate Energy

25

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Recommendations
ccASHP Electrification Opportunities in the Dane County Housing Stock
Implementing ccASHPs in Dane County has the potential to reduce total residential housing carbon
emissions by 6-36% across the electric, propane, and fuel-oil heated housing stock. Carbon savings andupgrade costs will vary based on existing conditions, and the quantity of a particular housing stock
across Dane County will impact its overall opportunity for carbon savings from electrification. With thisin mind, we present the following recommendations that focus on specific niches most opportune for
initial ccASHP implementation programs in Dane County.

Recommendations In the Electric Resistance Sector
We recommend expanding ccASHP electrification efforts to residences with electric resistance heat.
Both single-family and multi-family electric resistance housing stocks can be converted to ccASHPs in
most scenarios at a lower cost as compared to propane and fuel-oil heated homes, while also resulting
in higher carbon savings and targeting more lower income households.
a. To achieve the highest carbon and utility savings on a per unit basis, offer ccASHP programs aimed
at replacing electric resistance heating in the single-family housing sector. This sector has the highest
per unit carbon savings (3.1-5.2 tons carbon saved per unit), highest utility savings ($1,100-$1,350
saved annually per unit), and lowest average simple payback (10 years) of the housing stocks
analyzed.
Single-family detached homes heated with electric resistance heat represent a sizable portion of theelectric resistance heating sector (9,352 units). Single-family homes also have the highest per unit
carbon savings across all building types considered. This is due to their higher baseline heating energy
consumption (largely due to a single-family home having greater thermal loss through the building
envelope). Converting the single-family electric heat sector to ccASHPs is projected to save 3.1-5.2 tonsof carbon per unit. This equates to 48-52% savings on heating and cooling emissions, and 30-36% on
total home carbon emissions. This amounts to utility savings of $1,100-$1,350 per year. The simple
payback based on the estimated upgrade cost and utility savings is 10 years. Aggregated, these per unit
savings across the county are expected to be between 35,000-45,000 tons of carbon saved annually if all
single-family homes with electric resistance heat are converted to ccASHPs.
b. To achieve the largest scale of impact, offer ccASHP programs aimed at replacing electric resistanceheating in the multi-family housing sector. This sector has the largest opportunity for carbon andutility savings based on the number of units (nearly 34,000), with moderate per unit carbon savings(1.0-1.8 tons carbon saved annually per unit) and utility savings ($330-$470). This housing stock also
has the lowest expected upgrade cost ($8,500 per unit).
Multi-family units make up the largest portion of the electric heat market in Dane County (33,932 units).
These units are expected to save 1.0-1.8 tons of carbon per unit annually. This equates to 46-51%
savings on cooling and heating carbon emissions, and 26-29% on total home emissions on a per unit
basis. This amounts to utility savings of $330-$470 per year per unit. The simple payback for electrifying
this housing sector is 23 years, which is higher than the single-family electric resistance sector but
significantly lower than the fuel-oil and propane sectors. Converting all multi-family electric resistance©2022 Elevate Energy

26

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stockunits to ccASHPs across Dane County is expected to save 40,000-55,000 tons of carbon annually. The
multi-family electric resistance sector also has the lowest upgrade cost across the housing types weanalyzed, with an estimated cost of $8,500 per unit.
Initial ccASHP programs may benefit from focusing on this segment due to its lower upfront cost andlarger number of units. However, there are specific barriers within multi-family markets that programs
should consider, such as the split incentive between building owners and residents. Residents often pay
the heating bill when the heating systems are electric, and thus building owners investing in heat pumps
will not receive the utility savings benefits; therefore, programs should be designed in a way thatbuilding owners who don’t pay for the electric heat are still incentivized to adopt heat pumps.
c. Assist lower income households by prioritizing upgrades in the electric resistance heating building
stock. Lower household incomes are associated with higher prevalence of electric heated homes in
Dane County.
Electric heating is associated with lower median household incomes in Dane County, indicating that
ccASHP programs focused on electric baseboard systems will be likely supporting lower-income
residents. Over the long term, as natural gas customer bases shrink, research suggests that homes
remaining reliant on fossil fuels risk paying a higher proportion of pipeline and other fixed infrastructure
costs in their utility bills (Davis and Hausman, 2022). Prioritization of low-income residents inelectrification efforts is important to ensure they do not bear the brunt of legacy infrastructure systems.
In addition, residences who convert from electric resistance to ccASHPs can expect substantial utility billsavings. Expected utility savings vary from single-family to multi-family. The average annual heating billsavings is about $400 per unit for a multi-family electric resistance unit, and $1,200 per home for singlefamily. These utility savings estimates are averages across a range of buildings within the single or multifamily housing stock, and actual savings will depend on the individual characteristics and variations
between buildings. Single-family utility bill savings are higher due to single-family home’s higher
baseline energy use.
d. Target urban census tracts for ccASHP programs aimed at replacing electric resistance heating.
Electric heating is concentrated in urban areas across Dane County.
Geographically, electric resistance systems are concentrated in urban census tracts (Figure 2). We
recommend concentrating conversion of electric resistance heating systems to ccASHPs in these areas,
including areas within the City of Madison on the Northside, Southwest side, and Isthmus, as well as
areas within the cities of Sun Prairie, Middleton, Verona, Mount Horeb, and Stoughton. That being said,
electric resistance systems are located in many areas in Dane County, regardless of urban/rural status.
An interactive map exploring the frequency of heating fuels by census tract may be useful for targeting
programs and can be found here.
In terms of existing heating system type, both electric baseboards and electric furnaces comprise theelectric resistance heating sector. Therefore, electrification of these systems will involve both ductlessand ducted ccASHP retrofits, and implementation programs should be able to support either of theseapproaches. One of the benefits of upgrading from electric resistance heat to heat pumps is it is likelythat this conversation will not require increasing the electrical capacity of the residence or building. This
makes the retrofit more straightforward while reducing the cost as compared to retrofits where theexisting heating fuel is not electric.

©2022 Elevate Energy

27

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Recommendations and Programmatic Considerations Across All Heating
Types
We recommend the following key programmatic recommendations across all heating types.
a. Target ccASHP programs to homes without air-conditioning, as approximately one-third ofresidential units do not currently have access to air-conditioning and adding cooling represents asignificant opportunity to improve housing infrastructure health and resiliency to residents during
increasingly occurring extreme temperature events. The portion of households without airconditioning is relatively consistent across Dane County geographies and heating types.
In the U.S., extreme heat is one of the leading causes of death for weather-related events. According toDane County’s Climate Action Plan, daily high temperatures exceed 90 degrees for 10-15 days per year
in Southern Wisconsin currently. This number is expected to increase to 30-40 days per year by 2050. As
extreme temperature events increase in Southern Wisconsin, comfort offered by air conditioning will
become a health and safety necessity. ccASHPs offer a less carbon-intensive way to provide heat, while
also providing access to air conditioning that is integrated into the same system. While adding coolingwill increase cooling carbon emission in a portion of the housing stock, overall carbon is still reduced
from the heating efficiency gains, while also providing health and resiliency benefits aligned with DaneCounty’s Climate Action Plan.
Importantly, carbon savings vary based on the existing cooling system prior to ccASHP conversion.
Residences with a cooling system (nearly two-thirds of the Dane County housing stock have either
central or window unit air-conditioning) are expected to reduce cooling carbon emissions due to theincreased cooling efficiency of the ccASHP. This corresponds to an average annual utility savings inresidences already with cooling of $15-$35 per year.
The remaining one-third of residences, which per the ResStockTM database do not use cooling, will
increase carbon emissions with the ccASHP system. The Madison PUMA has slightly more residences
without any form of air conditioning (35%), compared to the West Dane County (30%) and East DaneCounty (29%) PUMAs. By heating type, 32% of electric heated units, 27% of propane heated units, and
28% of fuel-oil heated units are estimated to not have cooling. Adding ccASHPs to units without airconditioning is expected to decrease total carbon savings by 6-23% (depending on the housing stock),corresponding to an increase in cooling utility bills between $40-$100 per year. However, across all
housing stocks considered, there are net positive carbon savings and utility savings when accounting forboth heating and cooling efficiencies. While there is still a net reduction in carbon emissions from
implementing ccASHPs, it is important for ccASHP programs to communicate expectations to consumers
to expect an increase in cooling costs during the summer months if they do not already have air
conditioning.
b. Create a core program dedicated to electrifying residential buildings to scale electrification ofhomes in Dane County. Because of the inherent biases to ccASHP technology, lack of contractors, andrelatively small incentives, a one-stop-shop approach that aligns existing programs and resources
available in Dane County is recommended.
The following program design considerations are recommended to increase the uptake and acceptanceof ccASHP technology in Dane County:©2022 Elevate Energy

28

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

•

•

•
•

•

An incentive or subsidy unique to Dane County to address costs of installing a new system.
Research completed through the Focus on Energy program (CEE, 2021) shows that at least a
50% subsidy is needed for homeowners to convert to heat pump technology. This is especiallycritical to address the longer simple payback periods currently associated with current ccASHP
technology.
Robust technical assistance to help homeowners with each step of the upgrade process. At aminimum this should include no-cost assessments to determine eligibility, assistance withequipment and contractor selection, and assistance with education related to operation andmaintenance of the new system. A bulk-buy program similar to the MadiSUN program thatprovides owners with comprehensive assistance and preferential costing could be aconsideration for ccASHPs.
Linking a ccASHP program to existing programs such as weatherization, Focus on Energy and/or
the Efficiency Navigator. This will help streamline outreach and education as well as potentiallycoordinate installations with other upgrade opportunities including energy efficiency and solar.
Contractor training to increase the pool of contractors that can reliably install ccASHPs
throughout Dane County and offer operation and maintenance services. Any contractor
engagement program should include an emphasis on increasing the number of MWDVBE(Minority-, Women-, Disabled-, and Veteran-owned Business Enterprise) contractors installing
ccASHP technology through a recruitment and training program specific to the needs of small
MWBE contractors. Creating linkages to existing small business resources for contractors in
Dane County should be part of any training opportunity.
Access to financing to provide homeowners and building owners additional funds, if needed forbuilding upgrades.

c. Complete a similar study for homes heated by natural gas.
Currently, the low cost of natural gas has negatively impacted the economic viability of installing
ccASHPs in homes. However, natural gas prices are susceptible to greater volatility in the future. This
winter, households heated with natural gas are expected to pay 30% more on average compared to last
winter. 12 A similar study should be undertaken in the near term to examine ccASHP economics undervarious natural gas pricing scenarios.

Recommendations In the Fuel-oil and Propane Sector
a. For ccASHP program aimed at conversion of fuel-oil and propane heated residences, focus initiallyon single-family housing stocks located in rural census tracts. While fuel-oil and propane residences
have higher simple paybacks and generally lower carbon savings as compared to electric resistancehomes, this housing stock is a key segment outlined in the Dane County Climate Action Plan andimportant to not leave behind in electrification efforts.
Converting residences with propane or fuel-oil heat to heat pumps is a key policy measure identified in
the Dane County Climate Action Plan to reduce carbon emissions. Across Dane County, propane systems
comprise of 12,769 units (5% of the building stock) and fuel-oil systems comprise of 2,074 units (1% of
the building stock). Unlike electric resistance heating, propane and fuel-oil heating is concentrated in the
single-family housing sector, with 89% of propane/fuel-oil residences being single-family. Therefore, we

12

https://www.eia.gov/outlooks/steo/report/WinterFuels.php©2022 Elevate Energy

29Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

recommend initial ccASHP programs target single-family households for converting propane or fuel-oil
systems.
Propane heating is concentrated in rural census tracts (Figure 3). Programs aimed at addressing heating
and cooling in rural areas would benefit from focusing on propane furnaces in single-family homes
initially. There are relatively few fuel-oil systems across Dane County, and programs aimed at converting
fuel-oil systems to heat pumps may run into challenges with targeting these systems. Programs aimed atfuel-oil systems will need outreach strategies and additional data analysis (e.g., tax assessor files) tolocate homes with these systems.
The overall potential of this sector to reduce carbon emissions is less than that of the electric resistancesector because there are fewer homes with propane or fuel-oil heat in Dane County. The expectedcarbon savings for fuel-oil and propane is also highly dependent on the composition of the electricity
grid. Unlike electric resistance, the carbon savings for fuel-oil and propane systems increase as the gridhas more renewable energy (i.e., low renewable energy cost scenario). For fuel-oil, the expected carbon
savings is between 2.2-3.9 tons saved per unit, corresponding to 18-34% total home carbon savings. This
corresponds to an annual utility savings of $340-$475 per year. On a per unit basis, the expected carbon
savings for propane is 1.0-2.4 tons annually, corresponding to 10-24% total home carbon savings perunit. This corresponds to an annual utility savings of $310-$410 per year.
In terms of heating system type, the most common type of propane and fuel-oil system is a ducted
furnace. We recommend implementing programs targeting both propane and fuel-oil ducted furnace
retrofits. The upgrade cost for both propane and fuel-oil single-family homes is similar, about $16,500
per unit. This cost estimate includes adding electrical capacity to the home to accommodate theadditional electric load of an all-electric heating system. In comparison, upgrading a propane furnace atthe end of its life to a standard efficiency equivalent furnace with air conditioning is estimated to cost
$7,000, while upgrading a fuel-oil furnace is expected to cost $10,000. Of note, propane homes have theoption to convert to a dual-fuel system, instead of an all-electric system. A dual fuel system relies on
propane heat during extreme temperature events, while utilizing the efficiency offered by heat pumps
for the majority of the heating season when not under extreme conditions. The dual-fuel systems canbenefit consumers by assuring adequate heat in extreme conditions, extending the useful life of their
existing propane system, and having a lower upfront cost than the full electric replacement.

©2022 Elevate Energy

30Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

References
CARD (2017). Cold Climate Air Source Heat Pump. https://www.mncee.org/sites/default/files/reportfiles/86417-Cold-Climate-Air-Source-Heat-Pump-%28CARD-Final-Report-2018%29.pdf.
CARD (2018). Minnesota Energy Efficiency Potential Study 2020-2029. https://mn.gov/commercestat/pdfs/mn-energy-efficiency-potential-study.pdf.
CEE (2021). Air Source Heat Pumps in Wisconsin Multi-family and Single-Family Applications.
https://www.focusonenergy.com/sites/default/files/inline-files/2021/EERD_ASHP_ProjectFinal_Report.pdf.
CEE (2020). Turning Up the Heath on Cold Climate Heat Pumps: A Statewide Approach.
https://www.mncee.org/sites/default/files/report-files/ACEEEccHP%20%282%29.pdf
Davis and Hausman (2022). Who Will Pay for Legacy Utility Costs?. Energy Institute at Haas.
http://www.haas.berkeley.edu/wp-content/uploads/WP317.pdf.
EIA (2021). Carbon Dioxide Emissions Coefficients.
https://www.eia.gov/environment/emissions/co2_vol_mass.php
EIA (2019). Wisconsin Energy Consumption by End-Use Sector.
https://www.eia.gov/state/?sid=WI#tabs-2.

©2022 Elevate Energy

31Characterization of Cold Climate ASHPs in Dane County’s Residential Housing StockAppendix A: Quantitative Analysis
ResStockTM Database
The National Renewable Energy Laboratory’s (NREL) ResStockTM data tool was obtained to understandthe prevalence and geo-locations of propane and other non-gas fuel residential buildings. Data points
included detailed building characteristics for each residential unit (e.g., square footage, heating system
type, heating system efficiency) that serve as inputs into energy models. ResStockTM then uses Open
Studio Energy+ to create physics-based models of annual baseline energy use by end-use and fuel (e.g.,heating fan electricity consumption, heating propane energy consumption) for each building type andresidential unit.
The resulting data offers a granular look at housing stock and baseline energy use profiles for residential
units across Dane County. However, there were some limitations to the data due to its lack of census
level survey and parcel level information. All data results analyzed are an approximation at the PUMA
level geography. The sample size of the modeled energy use was also dependent on the frequency of
the type of building stock, so building types that are less common in Dane County have smaller sample
sizes in this analysis. For example, of the 20,000 models, there were 4,984 models for buildings withelectric heat in Dane County. Conversely, there were only 173 models for buildings with fuel-oil heat.
The sample size for each segment of housing stock that provides the basis of the analysis is specified in
the resulting tables. To extrapolate to the total number of units in Dane County a weight of 11.99 isapplied. This weight represents the weight of each residential unit modeled relative to the total numberof units in Dane County (239,841).

Energy Savings Calculations
For each housing type and system, energy consumption for the new ccASHP system was estimated using
the following steps. First, all energy-end uses associated with heating or cooling were pulled from
ResStockTM. Depending on the type of heating or cooling system, this included one or more of thefollowing: (1) heating fuel energy use, (2) heating equipment efficiency, (3) cooling compressor energyuse, (4) cooling equipment efficiency, (5) backup heating energy, (6) heating fan energy, and (7) cooling
fan energy. Average end-use energy was calculated for each housing stock of interest (e.g., single-familywith propane furnace heating and central cooling).
Next, the estimated ccASHP annual electric use was determined first converting all the energy end-use
values to kilowatt-hours. Pre-retrofit heating and cooling energy was divided by an estimated COP(Coefficient of Performance) or SEER (Seasonal Energy Efficiency Ratio) of the new ccASHP system,
respectively. The seasonal COP is an hourly-weighted average of the heat pump COP based on outside
air temperature. The number of hours at each temperature we used were from typical meteorologicalyear (TMY3) data for Madison, Wisconsin. The heat pump is assumed to be not heating when theoutside temperature is warmer than 60°F. COP values as a function of outside temperature were takenfrom measured data of a ccASHP in Minnesota (CARD, 2017). From this data, 13,028 COP-hours across5,998 hours was estimated, arriving at a seasonal average COP of 2.2. For SEER, a new ccASHP SEER of
18 was assumed, based on the average efficiency ratings of ccASHPs currently available on the market
applicable to Wisconsin (Center for Energy and Environment, 2021). For residential units without air
conditioning, the post-retrofit cooling energy use was assumed to be equivalent to the average cooling©2022 Elevate Energy

32

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stockenergy use of the same type of housing stock. Fan energy was estimated to be reduced by 15% based on
improved efficiencies from an ECM (Electronically Commutated Motor).
Energy consumption after the retrofit was subtracted from the before-retrofit energy use to arrive at
the estimated energy savings for each building type of interest. Before-retrofit energy use was pulled
directly from the ResStockTM database. After-retrofit utility bill savings were calculated using average
fuel rates (Table 1). Each rate was multiplied by the energy use by fuel type before and after the ccASHP
retrofit. Utility costs after the retrofit were subtracted from the utility cost before the retrofit to arrive
at total annual heating bill cost savings.

ASHP Upgrade Cost Estimates
ccASHP upgrade cost depends on the existing building type and heating system. The proposed air source
heat pumps come in two styles – ducted split system and ductless mini-split system. A ducted split
system resembles a typical air conditioner system that is associated with residential furnaces. In one
possible arrangement, a cooling/heating coil is mounted in or near a furnace and uses the furnace fan tocirculate air through the home (Figure 7).
Figure 7. Depiction of ducted split system heat pump with furnace 13

The second style option is a ductless mini-split heat pump system. This system has its own indoor unitthat is not associated with a furnace or air handler. It is located in the room it serves and can bemounted on a wall or ceiling. Figure 8 shows wall-mounted and ceiling-mounted configurations.

Figure 8. Depiction of a ductless mini-split heat pump system 14
https://www.furnaceacexperts.ca/heat-pumps/
https://www.homedepot.com/p/Ramsond-18-000-BTU-1-5-Ton-Ductless-Mini-Split-Air-Conditioner-and-HeatPump-220V-60Hz-55GW2/203013148; https://www.compassheatingandair.com/ductless
13
14©2022 Elevate Energy

33

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing StockFor our upgrade cost estimates, if a unit’s existing heating system already has ducts (e.g., a central
furnace), a ducted heat pump air handler with electric resistance supplemental heat was proposed. The
existing duct system is assumed to be adequate. If a unit’s existing heating system did not haveductwork (e.g., electric baseboard heat), a ductless mini-split heat pump system was proposed withmultiple heads. In one scenario the existing heating system is retained for the supplemental heat; in allother cases the electric heat is added.
The primary source for cost information was RSMeans. Material costs for cold climate heat pumps,
which were not in RSMeans, were provided from a recent report for heat pump in Wisconsin (Center for
Energy and Environment, 2021). Included in the cost estimates are the following: heat pump material
cost, backup electric resistance heat, electrical upgrade costs (fuel heating only), furnace demolition(furnaces only), programmable thermostat(s) and labor. To account for costs of items that do not havereadily available itemized costs, a certain percentage was added to the subtotal of the itemized costs.
This added percentage ranged from 25-35% depending on the complexity of the system. A 5.5% sales
tax was also added that includes the state sales tax of 5.0% and the county sales tax of 0.5%.
Material costs depended on the size of heat pump installed. For multi-family buildings, two 1-ton
ductless split heat pumps are proposed. In actuality, this size may vary based on the need for heating
and cooling. We assume one system serves the living room and the other serves a bedroom. Studio units
may need only one system, while units with more bedrooms may need more systems.
For systems with furnaces, we assume each furnace is replaced with a 1.5-ton heat pump air handler
with a 10 kW electric resistance heater for supplemental heat. In actuality this cost could be lower incases where the existing furnace is adequate and the retrofit would be to add the heat pump coil, andfor supplemental heat add an electric resistance heater or keep the existing heater. A full list of the
upgrade cost by existing housing and system type can be found in Table 13.
Table 13. ccASHP Upgrade Cost by Housing and Heating System Type
Housing Type

©2022 Elevate Energy

Heating System Type

Total Units(Dane
County)New
ccASHPType

UpgradeCost($/Unit)34

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Multi-family (5+ Units)
Multi-family (5+ Units)
Single-Family DetachedSingle-Family DetachedSingle-Family DetachedSingle-Family DetachedSingle-Family DetachedSingle-Family DetachedSingle-Family Detached
Mobile Home
Multi-family (2-4)
Multi-family (5+ Units)
Multi-family (5+ Units)
Mobile Home
Single-Family Attached
Multi-family (2-4)
Single-Family AttachedSingle-Family Detached
Multi-family (2-4)
Multi-family (5+ Units)
Multi-family (2-4)
Single-Family Attached
Mobile Home
Multi-family (5+ Units)
Multi-family (5+ Units)
Multi-family (5+ Units)
Multi-family (5+ Units)
Single-Family AttachedElectricity Baseboard
Electricity Electric Furnace
Propane Fuel Furnace
Electricity Baseboard
Electricity Electric Furnace
Propane Fuel Wall/Floor Furnace
Fuel-oil Fuel Furnace
Propane Fuel Boiler
Fuel-oil Fuel Boiler
Propane Fuel Furnace
Propane Fuel Furnace
Propane Fuel Furnace
Propane Shared Heating
Propane Fuel Wall/Floor Furnace
Propane Fuel Furnace
Propane Shared Heating
Propane Fuel Wall/Floor Furnace
Fuel-oil Fuel Wall/Floor Furnace
Propane Fuel Wall/Floor Furnace
Propane Fuel Wall/Floor Furnace
Propane Fuel Boiler
Propane Fuel Boiler
Fuel-oil Fuel Furnace
Propane Fuel Boiler
Fuel-oil Shared Heating
Fuel-oil Fuel Boiler
Fuel-oil Fuel Furnace
Fuel-oil Fuel Furnace

12,877
9,688
7,482
5,324
4,053
2,710
1,391
719
564
432
312
276
204
156
156
108
72
60
48
36
24
24
12
12
12
12
12
12

Ductless
DuctedDuctedDuctless
DuctedDuctless
DuctedDuctless
Ductless
DuctedDuctedDuctedDuctless
DuctedDuctless
Ductless
Ductless
Ductless
Ductless
Ductless
Ductless
Ductless
DuctedDuctedDuctedDuctless
Ductless
Ductless$8,698$11,468$16,458$13,047$11,468$15,380$16,458$15,380$15,380$16,458$16,458$16,458$10,683$16,458$9,394$10,683$15,380$15,380$10,683$10,683$10,683$15,380$16,458$16,458$16,458$10,683$10,683$10,683

Carbon Savings Scenarios
The carbon savings are built on the energy savings results and compare the carbon impacts of the allelectric scenarios against what the emissions would be in the alternate fossil fuel scenarios. While manystudies rely on EPA’s eGrid for electricity emissions factors, eGrid numbers reflect the carbon intensityof the grid only at a current single point in time. For an electrification analysis, we believe using this typeof static emissions factor gives an incomplete and inaccurate picture of carbon emissions. The carbon
intensity of the grid changes every year and we expect that over the next 20 years the grid will get
cleaner to some degree, and that change should be reflected in the carbon analysis.
In order to reflect these grid changes, we used the Cambium tool produced by the National Renewable
Energy Laboratory (NREL). Cambium is a web-based tool that provides metrics for various modeled
future scenarios. Since predicting the future is of course imperfect, we are using two different futurescenarios for comparison in this analysis. The two scenarios are as follows:©2022 Elevate Energy

35

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock•Business as Usual: also referred to as Mid-Case by NREL, this scenario uses current policies anddefault or mid-level assumptions to generate a reference case. This scenario reflects changes in
the grid over time, but only changes that flow from the current business-as-usual factors andpolicies.

•

Low Renewable Cost: this scenario is modeled using low costs for renewable energy, therefore
increasing the share of renewables on the grid compared to other sources. Unlike business-asusual, this scenario reflects shifts in the factors that influence the fuel mix of the grid. Given thelikely policy and subsidy changes on the horizon, we feel this low-renewables cost scenario is avery likely and reasonable future model to use.

The Cambium tool produces an emissions factor for every even-numbered year in a given scenario.
Assuming a 20-year lifetime for heat pumps, we averaged the factors from 2020-2040 to arrive at thesingle emissions factor shown in the table below. For fossil fuel emissions factors EIA values were used,as the carbon intensity of a particular fossil fuel does not significantly change over time. The following
table reflects all emissions factors used in this analysis (Table 1414).
Table 14. Emission Factor Inputs Into Carbon Analysis Models
Fuel

Emissions Factors
1,027 lbs CO2 per MWh, business as usual

Electricity

SourceCambium

782 lbs CO2 per MWh, low renewable cost

Propane12.7 lbs CO2 per gallon

Fuel-oil

22.5 lbs CO2 per gallon

Natural Gas 121.3 lbs CO2 per 1,000 cubic feet

©2022 Elevate Energy

EIA, 2021
EIA, 2021
EIA, 2021

36

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing StockAppendix B: Dane County Housing Stock
Table 1515 contains a full list of all the housing and heating type pairs in Dane County, sorted byprevalence. The Total Units (ResStockTM Sample) represents the count of the numbers of units for eachhousing/heating pair in the ResStockTM database, which provides the sample size for the basis of theanalysis. The Total Units (Dane County) represents the total number of units for each housing/heating
pair across Dane County. A constant weight of 11.99 is applied to calculate the total units across DaneCounty.
Table 15. Full List of Housing and Heating Types in Dane County
Housing Type

Heating System TypeMulti-family (5+ Units)
Multi-family (5+ Units)
Multi-family (5+ Units)
Single-family (Detached)
Single-family (Detached)
Single-family (Detached)
Multi-family (5+ Units)
Multi-family (2-4)
Single-family (Detached)
Multi-family (2-4)
Multi-family (2-4)
Single-family (Attached)
Single-family (Detached)
Multi-family (5+ Units)
Single-family (Detached)
Single-family (Attached)
Single-family (Detached)
Multi-family (5+ Units)
Single-family (Detached)
Multi-family (2-4)
Mobile Home
Multi-family (2-4)
Single-family (Attached)
Multi-family (5+ Units)
Multi-family (5+ Units)
Multi-family (5+ Units)
Multi-family (5+ Units)

Electricity Baseboard
Electricity Shared Heating 15
Electricity Electric Furnace
Propane Fuel Furnace
Electricity Baseboard
Electricity Electric Furnace
Electricity ASHP
Electricity Baseboard
Propane Fuel Wall/Floor Furnace
Electricity Electric Furnace
Electricity Shared Heating
Electricity Baseboard
Fuel-oil Fuel Furnace
NoneElectricity ASHP
Electricity Electric Furnace
Propane Fuel Boiler
Other Fuel Shared Heating
Fuel-oil Fuel Boiler
Electricity ASHP
Propane Fuel Furnace
Propane Fuel Furnace
Electricity ASHP
Propane Fuel Furnace
Electricity Electric Wall Furnace
Electricity Electric Boiler
Propane Shared Heating

Total Units(ResStock
Sample)
1,074
948
808
624
444
338
300
277
226
204
143
122
116
109
104
64
60
52
47
44
36
26
24
23
22
21
17

Total Units(Dane
County)12,877
11,367
9,688
7,482
5,324
4,053
3,597
3,321
2,710
2,446
1,715
1,463
1,391
1,307
1,247
767
719
623
564
528
432
312
288
276
264
252
204

Percent of NonNatural Gas
Housing Stock
16.8%
14.8%
12.6%
9.7%
6.9%
5.3%
4.7%
4.3%
3.5%
3.2%
2.2%
1.9%
1.8%
1.7%
1.6%
1.0%
0.9%
0.8%
0.7%
0.7%
0.6%
0.4%
0.4%
0.4%
0.3%
0.3%
0.3%

The Shared Heating category is from survey respondents self-reported type of heating system. These
respondents reported a Shared Heating electric system, which had a similar energy profile to an electric baseboard
system, and we assumed people reporting a Shared System had an electric baseboard system.

15©2022 Elevate Energy

37

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Single-family (Attached)
Mobile Home
Mobile Home
Multi-family (2-4)
Single-family (Detached)
Single-family (Attached)
Single Family (Detached)
Multi-family (2-4)
Multi-family (2-4)
Single-family (Attached)
Multi-family (2-4)
Multi-family (2-4)
Single-family (Detached)
Single-family (Detached)
Multi-family (2-4)
Multi-family (5+ Units)
Single-family (Attached)
Multi-family (2-4)
Single-family (Attached)
Mobile Home
Single-family (Attached)
Mobile Home
Mobile Home
Multi-family (5+ Units)
Mobile Home
Multi-family (5+ Units)
Single-family (Attached)
Multi-family (5+ Units)
Multi-family (5+ Units)
Single Family (Attached)
Mobile Home

©2022 Elevate Energy

Propane Fuel Furnace
Propane Fuel Wall/Floor Furnace
Electricity Baseboard
Propane Shared Heating
Electricity Electric Wall Furnace
Electricity Shared Heating
None
Other Fuel Shared Heating
Electricity Electric Wall Furnace
Propane Fuel Wall/Floor Furnace
NoneElectricity Electric Boiler
Electricity Electric Boiler
Fuel-oil Fuel Wall/Floor Furnace
Propane Fuel Wall/Floor Furnace
Propane Fuel Wall/Floor Furnace
Electricity Electric Wall Furnace
Propane Fuel Boiler
Propane Fuel Boiler
Electricity ASHP
Electricity Electric Boiler
Electricity Electric Furnace
Electricity Electric Wall Furnace
Fuel-oil Fuel Boiler
Fuel-oil Fuel Furnace
Fuel-oil Fuel Furnace
Fuel-oil Fuel Furnace
Fuel-oil Shared Heating
Propane Fuel Boiler
None
None

13
13
10
9
8
7
7
7
6
6
6
5
5
5
4
3
2
2
2
1
1
1
1
1
1
1
1
1
1
1
1

156
156
120
108
96
84
84
84
72
72
72
60
60
60
48
36
24
24
24
12
12
12
12
12
12
12
12
12
12
12
12

0.2%
0.2%
0.2%
0.1%
0.1%
0.1%
0.1%
0.1%
0.1%
0.1%
0.1%
0.1%
0.1%
0.1%
0.1%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%
0.0%

38

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing StockAppendix C: Relationship between heating
fuel and income in Dane County
In addition to examining the relationship between income and electric space heating, this relationshipwas examined for other heating fuels including natural gas, propane, and fuel-oil. Unlike electric
resistance heat, the relationship between natural gas, propane, and fuel-oil with income was not clearly
evident (Figure 9, Figure 11) or did not appear linear (Figure 10). All graphs were made using data fromthe 2019 ACS.

Percent Units within a Census Tract with
Natural Gas Heat

Figure 9. Census tract median household income versus percent units with natural gas heat
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%

$0

$20,000 $40,000 $60,000 $80,000 $100,000 $120,000 $140,000 $160,000 $180,000

Median Household Income (2019)©2022 Elevate Energy

39

Characterization of Cold Climate ASHPs in Dane County’s Residential Housing Stock

Percent Units within a Census Tract with
Propane Heat

Figure 10. Census tract median household income versus percent units with propane heat
60%
50%
40%
30%
20%
10%
0%

$0

$20,000 $40,000 $60,000 $80,000 $100,000 $120,000 $140,000 $160,000 $180,000

Median Household Income (2019)

Figure 11. Census tract median household income versus percent units with fuel-oil heat
Percent Units within a Census Tractwith Fuel Oil Heat

6%
5%
4%
3%
2%
1%
0%

$0

$20,000 $40,000 $60,000 $80,000 $100,000 $120,000 $140,000 $160,000 $180,000

Median Household Income (2019)©2022 Elevate Energy

40Characterization of Cold Climate ASHPs in Dane County’s Residential Housing StockAppendix D: Recruitment outreach example©2022 Elevate Energy

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