San Mateo City Council
March 2, 2026

2025 Cost-
Effectiveness Study :

Single Family AC to Heat
Pump Replacement
Prepared by:

Ada Shen, Rebecca Evans, Keith
Saechao, Alea German, & Marc
Hoeschele, Frontier Energy, Inc
Misti Bruceri, Misti Bruceri &
Associates, LLC
Prepared for:

Kelly Cunningham, Codes and
Standards Program, Pacific Gas
and Electric
Revision: 2.0
Last modified: 2025/08/08

Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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Table 1. Summary of Revisions
Date Description Reference (page or section)
6/09/2025 Original Release N/A
8/08/2025 The following issues were corrected in this report. Note that none of the issues flipped cost-effectiveness results from cost- effective to not cost-effective or vice versa in any climate zone except for the DFHP in the 1978-1991 vintage in CZ 15 is now LSC cost-effective.

1. 30-year DFHP results for all sizes except the 3-ton
system have been impacted. Increase in cost-
effectiveness for Climate Zones 2,4,8-15, decrease in
cost effectiveness in Climate Zone 3.

Table 7, Table 8, Table 9,
Table 12, Table 15, Table 22,
Table 25, Table 28, Table 31,
Section 4: Recommendations
and Discussion
Legal Notice
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Copyright 2025, Pacific Gas and
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2. Incremental cost tables 7-9 had incorrect condensing furnace costs.

3. Zero NOx discussion in the recommendations and
discussion section was based on the high gas
escalation rates but were compared against the
modest escalation standard results. The discussion
has been corrected to compare against the high gas
escalation standard results instead.

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Acronym List
AC – Air conditioner
ACH50 – Air Changes per
Hour at 50 pascals pressure
differential
AFUE – Annual Fuel
Utilization Efficiency
B/C – Lifecycle Benefit-to-
Cost Ratio
BSC – Building Standards
Commission
CA IOUs – California
Investor-Owned Utilities
CARE – California Alternate
Rates for Energy
CASE – Codes and
Standards Enhancement
CBECC-Res – Computer
program developed by the
California Energy
Commission for
demonstrating compliance
with the California
Residential Building Energy
Efficiency Standards
CFM – Cubic Feet per
Minute
CO2 – Carbon Dioxide
CPAU – City of Palo Alto
Utilities
CPUC – California Public
Utilities Commission
CZ – California Climate
Zone
DFHP – Dual Fuel Heat
Pump
DHW – Domestic Hot Water
DOE – Department of
Energy
EDR – Energy Design
Rating
EER – Energy Efficiency
Ratio
EF – Energy Factor
GHG – Greenhouse Gas
HPWH – Heat Pump Water
Heater
HSPF – Heating Seasonal
Performance Factor
HVAC – Heating,
Ventilation, and Air
Conditioning
IOU – Investor Owned
Utility
kBtu – kilo-British thermal
unit
kWh – Kilowatt Hour
LCC – Lifecycle Cost
LLAHU – Low Leakage Air
Handler Unit
VLLDCS – Verified Low
Leakage Ducts in
Conditioned Space
NEEA – Northwest Energy
Efficiency Alliance
NEM – Net Energy Metering
NPV – Net Present Value
PG&E – Pacific Gas and
Electric Company
PV – Photovoltaic
SCE – Southern California
Edison
SDG&E – San Diego Gas
and Electric
SEER – Seasonal Energy
Efficiency Ratio
SF – Single Family
SMUD – Sacramento
Municipal Utility District
SoCalGas – Southern
California Gas Company
TDV – Time Dependent
Valuation
Therm – Unit for quantity of
heat that equals 100,000
British thermal units
Title 24 – Title 24, Part 6
TOU – Time-Of-Use
UEF – Uniform Energy
Factor
Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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Table of Contents
Executive Summary ............................................................................................................ 4 1 Introduction .................................................................................................................. 7 2 Methodology and Assumptions .................................................................................. 9

2.1 Modeling ............................................................................................................... 9

2.2 Prototype Characteristics .....................................................................................10

2.3 Cost-Effectiveness Approach ...............................................................................13

2.3.1 Benefits ...........................................................................................................13

2.3.2 Costs ...............................................................................................................13

2.3.3 Metrics .............................................................................................................15

2.3.4 Utility Rates .....................................................................................................16

2.4 Measure Details and Cost....................................................................................18

2.4.1 Lifecycle Cost Assuming Zero-NOx Standards for Space Heating After 2030 ..20 3 Results ........................................................................................................................ 22

3.1 Cost-Effectiveness Results ..................................................................................22

3.1.1 Cost Effectiveness Results Using Standard Tariffs ...........................................23

3.1.2 Cost Effectiveness Results Using CARE Tariffs ...............................................26

3.2 Zero-NOx Scenario Results .................................................................................28

3.3 AC Pathways for Heat Pump Replacements ........................................................30 4 Recommendations and Discussion .......................................................................... 33 5 References ................................................................................................................. 36 6 Appendices ................................................................................................................ 38

6.1 Map of California Climate Zones ..........................................................................38

6.2 Cost-Effectiveness Results ..................................................................................39

6.2.1 Standard Rates ................................................................................................39

6.2.2 CARE tariffs .....................................................................................................45

6.3 Utility Rate Schedules ..........................................................................................51

6.3.1 Pacific Gas & Electric.......................................................................................51

6.3.2 Southern California Edison ..............................................................................60

6.3.3 Southern California Gas ...................................................................................64

6.3.4 San Diego Gas & Electric ................................................................................65 Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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6.3.5 City of Palo Alto Utilities ...................................................................................72

6.3.6 Sacramento Municipal Utilities District (Electric Only) ...................................... 74

6.3.7 Fuel Escalation Assumptions ...........................................................................76

List of Tables
Table 1. Summary of Revisions ............................................................................................ 1 Table 2. Residential Prototype Characteristics ....................................................................10 Table 3. Efficiency Characteristics for Three Vintage Cases ................................................12 Table 4. System Sizing by Climate Zone .............................................................................15 Table 5. Investor-Owned Utility Tariffs Used Based on Climate Zone ..................................16 Table 6. Publicly Owned Utility Tariffs Used Based on Climate Zone ...................................17 Table 7. Lifecycle Incremental Cost Breakdown for a 4-Ton DFHP Existing Furnace ...........19 Table 8. Lifecycle Incremental Cost Breakdown for 4-Ton HPSH ........................................19 Table 9. HVAC Measure Cost Assumptions – 4-Ton Electric Replacements ........................20 Table 10. SCAQMD Rule 1111 Proposed Manufacturer Compliance Targets.......................20 Table 11. Lifecycle Incremental Cost Breakdown for 4-Ton System with no Gas Furnaces after 2030 ............................................................................................................................21 Table 12. [1992-2010] DFHP Existing Furnace ....................................................................23 Table 13. [1992-2010] Standard Efficiency HPSH ...............................................................24 Table 14. [1992-2010] High Efficiency HPSH ......................................................................25 Table 15. [1992-2010] DFHP Existing Furnace CARE .........................................................26 Table 16. [1992-2010] Standard Efficiency HPSH CARE ....................................................27 Table 17. [1992-2010] High Efficiency HPSH CARE ............................................................28 Table 18. DFHP Existing Furnace On-Bill NPV with High Gas Escalation (Zero-NOx Rule) 29 Table 19. DFHP Existing Furnace LSC Savings (Zero-NOx Rule) .......................................30 Table 20. New AC Only Path Cost Estimates ......................................................................32 Table 21. New AC/Furnace and New Ducts Path Cost Estimates ........................................32 Table 22. [Pre-1978] DFHP Existing Furnace ......................................................................39 Table 23. [Pre-1978] Standard Efficiency HPSH ..................................................................40 Table 24. [Pre-1978] High Efficiency HPSH .........................................................................41 Table 25. [1978-1991] DFHP Existing Furnace ....................................................................42 Table 26. [1978-1991] Standard Efficiency HPSH ...............................................................43 Table 27. [1978-1991] High Efficiency HPSH ......................................................................44 Table 28. [Pre-1978] DFHP Existing Furnace CARE ...........................................................45 Table 29. [Pre-1978] Standard Efficiency HPSH CARE .......................................................46 Table 30. [Pre-1978] High Efficiency HPSH CARE ..............................................................47 Table 31. [1978-1991] DFHP Existing Furnace CARE .........................................................48 Table 32. [1978-1991] Standard Efficiency HPSH CARE ....................................................49 Table 33. [1978-1991] High Efficiency HPSH CARE ............................................................50 Table 34. PG&E Baseline Territory by Climate Zone ............................................................51 Table 35. PG&E Monthly Gas Rate ($/therm) ......................................................................52 Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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Table 36. SCE Baseline Territory by Climate Zone ..............................................................60 Table 37. SoCalGas Baseline Territory by Climate Zone .....................................................64 Table 38. SoCalGas Monthly Gas Rate ($/therm) ................................................................65 Table 39. SDG&E Baseline Territory by Climate Zone .........................................................65 Table 40. SDG&E Monthly Gas Rate ($/therm) ................................................................... 66 Table 41. CPAU Monthly Gas Rate ($/therm) ......................................................................72 Table 42. Real Utility Rate Escalation Rate Assumptions, CPUC En Banc and 2022 TDV Basis ...................................................................................................................................77 Table 43. Real Utility Rate Escalation Rate Assumptions, 2025 LSC Basis .........................78 List of Figures
Figure 1. AC vs. Heat Pump Pathway Requirements ..........................................................31 Figure 2. AC vs. Heat Pump Energy Comparison ................................................................31 Figure 3. Map of California climate zones. ..........................................................................38

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Executive Summary
The California Codes and Standards (C&S) Reach Codes program, also known as the Local Energy Codes program, provides technical support to local governments considering adopting a local ordinance (reach code) intended to support meeting local and/or statewide energy efficiency and greenhouse gas (GHG) reduction goals. The program facilitates adoption and implementation of the code when requested by local jurisdictions by providing resources such as cost-effectiveness studies, model language, sample findings, and other supporting documentation.

It is important to note that there is a voluntary measure in the 2025 CALGreen for replacing an air conditioner with a heat pump at time of air conditioner replacement, which can be adopted as is. This report seeks to provide options to modify the heat pump measure and demonstrate the cost-effectiveness of these options.

This analysis used two different metrics to assess the cost-effectiveness of the proposed upgrades for a 1,665 square foot single family home prototype with an attached garage.

Both methodologies require estimating and quantifying the incremental costs and energy savings associated with each energy efficiency measure over a 30-year analysis period. On- Bill cost-effectiveness is an occupant-based lifecycle cost (LCC) approach that values energy based upon estimated site energy usage and customer utility bill savings using today’s electricity and natural gas utility tariffs. To reflect how natural gas prices fluctuate with seasonal supply and demand, a normalized curve was used to estimate the cost for the remaining months relative to today’s rates. Long-term Systemwide Cost (LSC) is the California Energy Commission’s metric for determining cost-effectiveness of efficiency measures in the 2025 Energy Code. This metric is intended to capture the long-term projected cost of energy including costs for providing energy during peak periods of demand, carbon emissions, grid transmission and distribution impacts.

Local jurisdictions may adopt ordinances that amend different parts of the California Building Standards Code or may elect to amend other state or municipal codes. The decision regarding which code to amend will determine the specific requirements that must be followed for an ordinance to be legally enforceable. For example, reach codes that amend Part 6 of the California Building Code (the Energy Code) and require energy performance beyond state code minimums must demonstrate the proposed changes are cost-effective and obtain approval from the Energy Commission as well as the Building Standards Commission (BSC). Amendments to Part 11, such as requirements for increased water efficiency or electric vehicle infrastructure only require BSC approval and do not require the Energy Commission approval. Although a cost-effectiveness study is only required to amend Part 6 of the California Building Code, this study provides valuable context for jurisdictions pursuing other ordinance paths to understand the economic impacts of the policy decision.

This study documents the estimated costs, benefits, energy impacts and greenhouse gas emission reductions that may result from implementing an ordinance based on the results to help residents, local leadership, and other stakeholders make informed policy decisions.

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The following summarizes key results:

1. Heat pumps are significantly more efficient than gas furnaces, requiring less than half the energy to meet the heating load. However, despite this reduction in heating energy use, the cost of heating a home using electricity (heat pump) could be higher than the cost to heat that same home with natural gas (furnace), depending on the electricity tariffs relative to the gas tariffs. Therefore, while a heat pump measure could be deemed as cost-effective over its lifecycle, installing a heat pump could result in a decrease or an increase in utility costs in the first years relative to a gas furnace and AC system.

2. The study assumes utility rates escalate over time. Because it is very difficult to predict how the rates will change, the analysis presents two escalation scenarios (modest and high gas escalation) to represent a range of outcomes.

3. The LSC metric most often produces more favorable cost-effectiveness results relative to the results produced using actual utility costs (On-Bill). When the analysis assumes a higher escalation rate for natural gas costs relative to electricity in future years (high gas escalation), the On-Bill results are more favorable in some cases. a. In the oldest (pre-1978) vintage, all three measures (dual fuel heat pump with existing furnace, standard heat pump space heater, and high efficiency heat pump space heater) are cost-effective using the LSC metric in all climate zones. When using the On-Bill metric, the measures remain cost-effective in most climate zones.
b. In the newer (1978-1991 and 1992-2010) vintages, the dual fuel heat pump (DFHP Existing Furnace) and the standard efficiency HPSH are cost-effective based on LSC in all cases except for Climate Zone 15 when using both the standard and California Alternate Rates for Energy (CARE) tariff.

4. Using the CARE tariff results in higher cost savings and cost-effectiveness relative to standard rates, with almost all cases yielding first year utility cost savings. The DFHP Existing Furnace is On-Bill cost-effective based on the high gas escalation scenario in all cases in the pre-1978 vintage, and almost all cases in the 1978-1991 and 1992-2010 vintage. It is also On-Bill cost-effective in most climate zones for the modest gas escalation scenario across all vintages. In Climate Zones 5, 8, 9, 10, 14, and 15, cost-effectiveness declines relative to other areas, and in some cases is not cost-effective from an On-Bill perspective. This is the case for both the CARE tariff and the standard rate.

5. The analysis also modeled the cost impact of using a standard time-of-use electricity tariff versus switching to a newer electrification tariff, designed to reduce costs in homes with heat pumps and/or electric vehicles. Older homes tend to be the least efficient and achieve the most savings from improving equipment efficiency. In most of the state, because older homes tend to use more electricity than a similarly sized, newer vintage home, they realize more costs savings under the electrification tariff.

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savings from switching tariffs; they generally perform better under the standard tariff.

This trend is different in milder climate zones in SCE territory (excluding CZ 15), where newer homes realize more cost savings. Both the standard and electrification tariffs in SCE territory include a daily allocation of lower-cost baseline electricity and a second, higher-priced tier when the baseline is exceeded. In many newer homes, a higher percentage of overall electricity use is within the baseline allocation, resulting in greater cost savings.

6. Higher efficiency equipment reduces utility costs in all cases and improves cost- effectiveness in many climate zones in the oldest vintage relative to standard efficiency equipment. However, in more efficient newer homes, where cost- effectiveness is generally lower, the savings are insufficient to offset the roughly $3,000 increase in incremental cost.

7. Given the adopted Bay Area Air Quality Management District (BAAD) Zero NOx rule, and the proposed California Air Resource Board or South Coast Air Quality Management District (SCAQMD) Zero-NOx rules, and gas furnaces are no longer available or less available to be installed in 2030, a sensitivity analysis was performed for the Zero NOx scenario and found that cost-effectiveness declines in many cases except in Climate Zones 8-10, some results improve enough to become cost-effective. The improved cost-effectiveness in Climate Zones 8-10 is due to the higher baseline cost when a HPSH must be installed at year 10 when the furnace must be replaced. However, the overall magnitude of 30-year On-Bill cost- effectiveness is lower because there are only 10 years of utility cost savings. After year 10 the base case and upgrade measures are both heat pumps.

This report documents the key results and conclusions from the Reach Codes Team analysis. A full dataset of all results can be downloaded at https://localenergycodes.com/content/resources. Results alongside policy options can also be explored using the Cost-effectiveness Explorer at https://explorer.localenergycodes.com/.

Model ordinance language and other resources are posted on the C&S Reach Codes Program website at LocalEnergyCodes.com. Local jurisdictions that are considering adopting an ordinance may contact the program for further technical support at [email protected].

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1 Introduction
The California Codes and Standards Reach Codes program, also known as the Local Energy Codes program, provides technical support to local governments considering adopting a local ordinance intended to support meeting local and/or statewide energy efficiency and greenhouse gas (GHG) reduction goals. The program facilitates adoption and implementation of the code when requested by local jurisdictions by providing resources such as cost-effectiveness studies, model language, sample findings, and other supporting documentation.

Local jurisdictions may adopt ordinances that amend different parts of the California Building Standards Code or may elect to amend other state or municipal codes. The decision regarding which code to amend will determine the specific requirements that must be followed for an ordinance to be legally enforceable. For example, reach codes that amend Part 6 of the California Building Code (the Energy Code) (CEC, 2025) and require energy performance beyond state code minimums must demonstrate the proposed changes are cost-effective and obtain approval from the Energy Commission as well as the Building Standards Commission (BSC). Amendments to Part 11, such as requirements for increased water efficiency or electric vehicle infrastructure only require BSC approval and do not require the Energy Commission approval. Although a cost-effectiveness study is only required to amend Part 6 of the California Building Code, this study provides valuable context for jurisdictions pursuing other ordinance paths to understand the economic impacts of the policy decision. This study documents the estimated costs, benefits, energy impacts and greenhouse gas emission reductions that may result from implementing an ordinance based on the results to help residents, local leadership, and other stakeholders make informed policy decisions.

This report is an update to the 2022 Single Family Retrofit Cost-effectiveness Study (Statewide Reach Codes Team, 2024) focused on an ordinance structure that encourages air conditioner (AC) to heat pump replacement. The methodology, prototype characteristics, and relevant measure packages are retained from the main study referenced above. The study includes updated utility rates, revised costs based on the TECH Clean California1 incremental cost study data, estimated costs for the AC path, updated and expanded AC path options, and a new cost-effectiveness scenario that considers upcoming proposed zero-NOx emission regulations (SCAQMD, 2025) (California Air Resources Board, 2022) (BAAD, 2025).

Local jurisdictions in California may consider adopting local energy ordinances to achieve energy savings beyond what will be accomplished by enforcing building efficiency requirements that apply statewide.

Local jurisdictions may also adopt ordinances that amend different parts of the California Building Standards Code or may elect to amend other state or municipal codes. The

1 https://techcleanca.com/
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decision regarding which code to amend will determine the specific requirements that must be followed for an ordinance to be legally enforceable. Although a cost-effectiveness study is only required to amend Part 6 of the CA Building Code, it is important to understand the economic impacts of any policy decision. This study documents the estimated costs, benefits, energy impacts and greenhouse gas emission reductions that may result from implementing an ordinance based on the results to help local leadership, residents, and other stakeholders make informed policy decisions.

This report was developed in coordination with the California Statewide Investor-Owned Utilities (IOUs) Codes and Standards Program, the California Energy Commission (CEC), key consultants, and engaged cities—collectively known as the Statewide Reach Codes Team. Model ordinance language and other resources are posted on the C&S Reach Codes Program website at LocalEnergyCodes.com. Local jurisdictions that are considering adopting an ordinance may contact the program for further technical support at [email protected].

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2 Methodology and Assumptions
This study evaluates a potential reach code that encourages a heat pump or dual fuel system that includes a heat pump combined with a furnace when an air conditioner is replaced or installed new in existing single family homes. The ordinance structure and this analysis is based on the voluntary requirements adopted in 2025 Title 24, Part 11 California Green Building Standards Code (CALGreen), Section A4.204.1.1 for heat pump space conditioning alterations in single family homes (California Energy Commission, 2025). The proposed reach code also defines pathways for air conditioning equipment to be installed combined with additional efficiency measures. The heat pump path requires the heat pump as the primary heat source, with backup heating allowable either provided by electric resistance or natural gas. In cases where the existing furnace remains, the heat pump is installed alongside the existing furnace with integrated controls to allow for the furnace to provide backup heating. In alignment with the 2025 Energy Code requirements the heat pump must be sized to satisfy the heating load at the design heating temperature without the use of backup heat.

All methodology and assumptions are consistent with prior statewide analysis (Statewide Reach Codes Team, 2024) with the following exceptions:

1. Updated utility rates to January 2025

2. Equipment costs based on TECH data where available; the original report was based on Statewide contractor survey costs

3. Cost estimates were obtained for the AC path

4. Expanded AC path options

5. Cost-effectiveness results for the scenario if gas furnaces are no longer available for sale in California in 2030

2.1 Modeling
The Reach Codes Team performed energy simulations using the 2025 research version of the Residential California Building Energy Code Compliance software (CBECC). The 2025 version of CBECC includes updated weather files, metrics, and the weather stations were changed in Climate Zones 4 and 6 from San Jose to Paso Robles and Torrance to Los Angeles International Airport, respectively. Note that at the time of this report, the Energy Commission was working on integrating a new heat pump model into the CBECC-Res software to better reflect the actual energy use of heat pumps. The updated model results in lower heating energy use than is currently estimated. Once the revised software is released, the reach codes team plans to update this analysis.

Three unique building vintages are included: pre-1978, 1978-1991, and 1992-2010. The vintages were defined based on review of historic building code requirements and defining periods with distinguishing features. The proposed measures were modeled to determine the projected site energy (therm and kWh), source energy, GHG emissions, and long-term systemwide cost (LSC) impacts. Annual utility costs were calculated using hourly data Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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output from CBECC, and updated (as of 1/1/2025) electricity and natural gas tariffs for each of the investor-owned utilities (IOUs) as appropriate for that climate zone.

Site energy results are similar between CBECC-Res 2022 and 2025. The 2025 compliance metrics include assumptions that more appliances will be electric in the future. This is predicted to result in higher natural gas retail rates as a result of gas utilities continuing to maintain safe and reliable infrastructure amidst declining natural gas use.

Equivalent CO2 emission reductions were calculated based on outputs from the CBECC- Res simulation software. Electricity emissions vary by region and by hour of the year.

CBECC-Res applies two distinct hourly profiles, one for Climate Zones 1 through 5 and 11 through 13 and another for Climate Zones 6 through 10 and 14 through 16. Natural gas emissions do not vary hourly. To compare the mixed-fuel and all-electric cases side-by-side, GHG emissions are presented as pounds of CO2-equivalent (CO2e) emissions.

The Statewide Reach Codes Team designed the approach and selected measures for evaluation based on the 2019 existing building single family reach code analysis (Statewide Reach Codes Team, 2021) and supporting analysis used in the 2025 Energy Code development cycle as well as from outreach to architects, builders, and engineers.

2.2 Prototype Characteristics
The Energy Commission defines building prototypes which it uses to evaluate the cost- effectiveness of proposed changes to Energy Code requirements. Average home size has steadily increased over time, and the Energy Commission single family new construction prototypes are larger than many existing single family homes across California. For this analysis, a 1,665 square foot prototype was evaluated. Table 2 describes the basic characteristics of the single family prototype. Additions are not evaluated in this analysis as they are already addressed in Section 150.2 of the Energy Code. In the 2025 Energy Code heat pumps are prescriptively required for space and water heating for additions (California Energy Commission, 2023).

Table 2. Residential Prototype Characteristics
Climate Zone Specification
Existing Conditioned Floor Area 1,665 ft2
Num. of Stories 1
Num. of Bedrooms 3
Window-to-Floor Area Ratio 13%
Attached Garage 2-car garage

Three building vintages were evaluated to determine sensitivity of existing building performance on cost-effectiveness of upgrades. For example, it is widely recognized that adding attic insulation in an older home with no insulation is cost-effective, however, newer homes will likely have existing attic insulation reducing the cost-effectiveness of an incremental addition of insulation. The building characteristics for each vintage were Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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determined based on either prescriptive requirements from the building code that were in effect or standard construction practice during that time period. For example, homes built under 2001 Title 24 are subject to prescriptive envelope code requirements very similar to homes built under the 2005 code cycle, which was in effect until January 1, 2010.

Table 3 summarizes the assumptions for each of the three vintages. Additionally, the analysis assumed the following features when modeling the prototype buildings. • Efficiencies were defined by year of the most recent equipment replacement based on standard equipment lifetimes.
• Individual space conditioning and water heating systems, one per single family building.
• Split-system air conditioner with natural gas furnace. • Gas cooktop, oven, and clothes dryer.

The methodology applied in the analyses begins with a design that matches the specifications as described in Table 3 for each of the three vintages. Heat pump space conditioning measures were modeled to determine the projected energy performance and utility cost impacts relative to the baseline vintage.

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Table 3. Efficiency Characteristics for Three Vintage Cases Building Component Efficiency
Feature Pre-1978 Vintage 1978-1991 Vintage 1992-2010 Vintage Envelope
Exterior Walls 2x4, 16-inch on center wood frame,
R-02
2x4 16 inch on center wood frame,
R-11
2x4 16 inch on center wood frame,
R-13
Foundation Type & Insulation Uninsulated slab (CZ 2-15) Raised floor, R-0 (CZ 1 & 16)
Uninsulated slab (CZ 2-15)
Raised floor, R-0 (CZ 1 & 16)
Uninsulated slab (CZ 2-15)
Raised floor, R-19 (CZ 1 & 16)
Ceiling Insulation & Attic Type
Vented attic, R-5 @ ceiling level for CZ
6 & 7,
Vented attic, R-11 @ ceiling level
(all other CZs)
Vented attic, R-19 @ ceiling level Vented attic, R-30 @ ceiling level Roofing Material & Color Asphalt shingles, dark
(0.10 reflectance, 0.85 emittance)
Asphalt shingles, dark
(0.10 reflectance, 0.85 emittance)
Asphalt shingles, dark
(0.10 reflectance, 0.85 emittance)
Radiant Barrier No No No
Window Type: U-factor/SHGC3 Metal, single pane: 1.16/0.76 Metal, dual pane: 0.79/0.70 Vinyl, dual pane Low-E: 0.55/0.40 House Infiltration at 50 Pascals 15 ACH50 10 ACH50 7 ACH50 HVAC Equipment
Heating Efficiency 78 AFUE (assumes 2 replacements) 78 AFUE (assumes 1 replacement) 78 AFUE Cooling Efficiency 10 SEER (assumes 2 replacements) 10 SEER (assumes 1 replacement) 13 SEER, 11 EER Duct Location & Details Attic, R-2.1, 30% leakage at 25 Pa Attic, R-2.1, 25% leakage at 25 Pa Attic, R-4.2, 15% leakage at 25 Pa Whole Building Mechanical
Ventilation None None None
Water Heating Equipment
Water Heater Efficiency 0.575 Energy Factor (assumes 2
replacements)

0.575 Energy Factor (assumes 1
replacement) 0.575 Energy Factor
Water Heater Type 40-gallon gas storage 40-gallon gas storage 40-gallon gas storage Pipe Insulation None None None
Hot Water Fixtures Standard, non-low flow Standard, non-low flow Standard, non-low flow

2 Pre-1978 wall modeled with R-5 cavity insulation to better align wall system performance with monitored field data and not overestimate energy use. 3 Window type selections were made based on conversations with window industry expert, Ken Nittler. If a technology was entering the market during the time period (e.g., Low-E during 1992-2010 or dual-pane during 1978-1991) that technology was included in the analysis. This provides a conservative assumption for overall building performance and additional measures may be cost-effective for buildings with lower performing windows, for example buildings with metal single pane windows in the 1978-1991 vintage
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2.3 Cost-Effectiveness Approach

2.3.1 Benefits
This analysis used two different metrics to assess the cost-effectiveness of the proposed upgrades. Both methodologies require estimating and quantifying the incremental costs and energy savings associated with each energy efficiency measure. The main difference between the methodologies is the way they value energy impacts:
• On-Bill: Customer-based lifecycle cost approach that values energy based upon estimated site energy usage and customer On-Bill savings using electricity and natural gas utility rate schedules over a 30-year duration, accounting for a three percent discount rate and energy cost inflation per Appendix 6.3.7. • Long-term Systemwide Cost (LSC): Formerly known as Time Dependent Valuation (TDV) energy cost savings, LSC reflects the Energy Commission’s current lifecycle cost (LCC) methodology, which is intended to capture the total value or cost of energy use over 30 years. This method accounts for the hourly cost of marginal generation, transmission and distribution, fuel, capacity, losses, and cap-and-trade- based CO2 emissions (California Energy Commission, 2023). This is the methodology used by the Energy Commission in evaluating cost-effectiveness for measures in the 2025 Energy Code.

Energy simulations were completed using the 2025 research version of the Residential California Building Energy Code Compliance software (CBECC).

2.3.2 Costs
The Reach Codes Team assessed the incremental costs and savings of the packages over the lifecycle of 30-years. Incremental costs represent the equipment, installation, replacement, and maintenance costs of the proposed measure relative to the 2025 Energy Code minimum requirements or standard industry practices.

In February 2024, the TECH Clean California statewide program completed an incremental cost study from cost data collected from 64 contractor participants (Opinion Dynamics, 2024). This report directly uses the TECH costs for all the scenarios for which there was TECH cost data available. These costs were supplemented with measure costs the Reach Codes Team obtained from a contractor survey conducted in the summer of 2023. Additional detail on the contractor cost survey is available in the prior existing building statewide study (Statewide Reach Codes Team, 2024). The following summarizes key assumptions in this costing approach.
• Average statewide costs from the TECH Study were used, no regional specific costs were applied.
• Costs for 3-ton and 4-ton units were scaled for smaller and larger systems based on linear interpolation between the 3-ton and 4-ton costs.

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• The TECH study provided cost for a minimum efficiency 60,000 Btu/h gas furnace.

However, beginning in 2028, newly installed residential gas furnaces must comply with updated federal efficiency standards requiring a minimum of 95% AFUE4.

Because the TECH study did not include cost estimates for a 95% AFUE condensing furnace, an adjustment was made using data from the statewide contractor cost survey. For systems requiring larger furnace capacities, cost estimates were derived as follows:
o 80,000 Btu/h furnaces (serving systems sized 3 tons): The cost difference between the minimum efficiency and 95% AFUE versions of the 80,000 Btu/h furnace and the cost difference between the minimum efficiency 80,000 Btu/h furnace and the minimum efficiency 60,000 Btu/h furnace, as reported in the contractor survey, was added to the TECH cost for the 60,000 Btu/h unit. o 100,000 Btu/h furnaces (serving systems 4 tons and larger): The same method was applied using the corresponding cost differential for 100,000 Btu/h units.
• At time of replacement for the heat pump, based on heating loads and contractor feedback it is assumed an electric resistance backup coil would be installed with the air handler for Climate Zones 1 and 16. The CBECC-Res software applies back up electric resistance heating for all climate zones whenever it is assumed that the heat pump cannot meet the heating load based on the performance of currently available products (Heinemeier, 2025).The TECH costs did not include this option. The $819 incremental cost from the statewide study was added in this case. • At the time of replacement for a furnace when it fails, the statewide study assumed a fan motor replacement. The TECH costs did not include this option. A $1,200 incremental cost was added to the TECH cost.
• At time of replacement for high efficiency heat pump, the sum of the TECH cost for standard efficiency heat pump and the incremental cost difference from the statewide study for high efficiency and standard efficiency heat pump was applied.

Costs were applied based on the system capacity from heating and cooling load calculations in CBECC-Res as presented in Table 4. Air conditioner nominal capacity was calculated as the CBECC-Res cooling load, rounded up to the nearest half ton. Heat pump nominal capacity was calculated as the maximum of either the CBECC-Res heating or cooling load, rounded up to the nearest half ton. In both cases a minimum capacity of 1.5- ton was applied as this represents the typical smallest available split system heat pump equipment. Load calculations revealed that Climate Zones 2 through 15 were cooling- dominated, whereas Climate Zones 1 and 16 were heating-dominated. In these heating-

4 https://www.energy.gov/articles/doe-finalizes-energy-efficiency-standards-residential-furnaces-save- americans-15-
billion#:~:text=These%20furnace%20efficiency%20standards%20were,heat%20for%20the%20livin g%20space.

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dominated zones, the heat pump was upsized compared to an air conditioner designed solely for cooling to ensure adequate heating performance.

Table 4. System Sizing by Climate Zone
Climate
Zone
Air Conditioner
Capacity (tons)
Heat Pump
Capacity (tons)
1 1.5 3.0
2 3.5 3.5
3 2.5 2.5
4 3.5 3.5
5 3.0 3.0
6 3.0 3.0
7 3.0 3.0
8 4.0 4.0
9 4.0 4.0
10 4.0 4.0
11 4.5 4.5
12 4.0 4.0
13 4.5 4.5
14 4.0 4.0
15 5.0 5.0
16 3.5 4.0

2.3.3 Metrics
Cost-effectiveness is presented using net present value (NPV). • NPV: The Reach Codes Team uses net savings (NPV benefits minus NPV costs) as the cost-effectiveness metric. If the net savings of a measure or package is positive, it is considered cost effective. Negative net savings represent net costs to the consumer. A measure that has negative energy cost benefits (energy cost increase) can still be cost effective if the costs to implement the measure are even more negative (i.e., construction and maintenance cost savings).

Improving the energy performance of a building often requires an initial investment. In most cases the benefit is represented by annual On-Bill utility or LSC savings, and the cost by incremental first cost and replacement costs. However, some packages result in initial construction cost savings (negative incremental cost), and either energy cost savings (positive benefits), or increased energy costs (negative benefits). In cases where both construction costs and energy-related savings are negative, the construction cost savings are treated as the benefit while the increased energy costs are the cost. In cases where a measure or package is cost-effective immediately (i.e., upfront construction cost savings and lifetime energy cost savings).

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2.3.4 Utility Rates
In coordination with the CA IOU rates team (comprised of representatives from Pacific Gas and Electric (PG&E), Southern California Edison (SCE) and San Diego Gas and Electric (SDG&E)) and two Publicly-Owned-Utilities (POUs) (Sacramento Municipal Utility District (SMUD) and City of Palo Alto Utilities (CPAU)), the Reach Codes Team determined appropriate utility rates for each climate zone to calculate utility costs and determine On-Bill cost-effectiveness for the proposed measures and packages. The utility tariffs, summarized in Table 5 and Table 6 with details in Section 6.2.26.2.2, were determined based on the appropriate rate for each. Utility rates were applied to each climate zone based on the predominant IOU serving the population of each zone, with a few climate zones evaluated multiple times under different utility scenarios. Climate Zones 10 and 14 were evaluated with both SCE for electricity and Southern California Gas Company (SoCalGas) for gas and SDG&E tariffs for both electricity and gas since each utility has customers within these climate zones. Climate Zone 5 is evaluated under both PG&E and SoCalGas natural gas rates. Two POU or municipal utility rates were also evaluated: SMUD in Climate Zone 12 and CPAU in Climate Zone 4.

First-year utility costs were calculated using hourly electricity and natural gas output from CBECC-Res and applying the utility tariffs summarized in Table 5 and Table 6. Homes with a heat pump in IOU territory are eligible for either the electrification or the standard tariff. Utility costs were calculated under both tariffs with results presented using the one that yielded the lower annual utility cost. The electrification tariff resulted in better utility costs savings when there was high kWh usage, typically in older, less efficient homes. Conversely, newer homes which are more efficient, tend to benefit more under the standard tariff. However, in SCE’s milder climate zones, older homes benefit more under the standard tariff. Annual costs were also estimated for IOU customers eligible for the CARE tariff discounts on both electricity and natural gas bills.

Table 5. Investor-Owned Utility Tariffs Used Based on Climate Zone Climate
Zones
Electric / Gas
Utility
Electricity
Tariff:

Standard
Rate
Electricity
Tariff:

Electrification
Rate
Natural Gas
Tariff
1-5,11-13,16 PG&E / PG&E E-TOU-C E-ELEC G1
5 PG&E / SoCalGas E-TOU-C E-ELEC GR
6, 8-10, 14, 15 SCE / SoCalGas TOU-D-4-9 TOU-D-PRIME GR 7, 10, 14 SDG&E / SDG&E TOU-DR-1 EV-TOU-5 GR

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Table 6. Publicly Owned Utility Tariffs Used Based on Climate Zone Climate
Zones
Electric / Gas Utility
Electricity Tariff: Standard
Rate
Electricity
Tariff:

Electrification
Rate
Natural Gas
Tariff
4 CPAU / CPAU E-1 G1
12 SMUD / PG&E R-TOD G1

Utility rates are assumed to escalate over time. Because it is very difficult to predict how rates will change, two escalation scenarios are presented in this study to represent a range of outcomes. See Appendix 6.3.7 Fuel Escalation Assumptions for details. 1) Modest Gas Escalation: This scenario is based on assumptions from the CPUC 2021 En Banc hearings on utility costs through 2030 (California Public Utilities Commission, 2021a). Escalation rates throughout the remainder of the 30-year evaluation period are based on the escalation rate assumptions within the 2022 Energy Code TDV factors developed by the Energy Commission (California Energy Commission. 2021b).
2) High Gas Escalation: This scenario is based on escalation rates developed by the Energy Commission and used within the 2025 Energy Code LSC factors (LSC replaces TDV in the 2025 Energy Code) which assumed steep increases in gas rates in the latter half of the analysis period.

Electricity tariff structures will evolve over time. Most recently, the CPUC approved an income-graduated fixed charge intended to benefit low-income customers and support electrification measures.5 The IOUs are currently developing tariffs that meet the direction given by the CPUC in this proceeding. These tariffs were not available at the time of this study, but this analysis may be re-evaluated later in 2025 once the rates are finalized.

5 https://www.cpuc.ca.gov/industries-and-topics/electrical-energy/electric-costs/demand-response- dr/demand-flexibility-rulemaking
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2.4 Measure Details and Cost
This section describes the details of the measures and documents incremental costs. All measure costs were obtained from the TECH cost survey and contractor survey unless otherwise noted. These surveys reflect the cost to the customer and include equipment, labor, permit fees, and required HERS testing.

The following heat pump space heater (HPSH) measures were evaluated as described below. All included HERS verified refrigerant charge, 10% duct sealing, and 300 CFM/ton airflow, aligned with the proposed code requirements for the 2025 Title 24 code. 1) Dual Fuel Heat Pump (DFHP Existing Furnace): Replace existing ducted AC with an electric heat pump and install controls to operate the heat pump as the primary space conditioning source and to use the existing gas furnace (78 AFUE) for backup heat when heating demands cannot be met by the heat pump. In this report, dual fuel heat pumps were modeled to disable furnace operation above an outdoor temperature of 35°F in compliance with Energy Code Section 150.0(h)7, which requires this lockout for any heat pump with supplemental heating. A minimum federal efficiency (14.3 SEER2, 11.7 EER2, 7.5 HSPF2) heat pump was evaluated.

Savings are compared to a new AC (14.3 SEER2, 11.7 EER2) alongside the existing furnace (78 AFUE). A new evaporator coil is assumed to be installed with the AC system.
2) HPSH: Replace existing ducted AC and natural gas furnace with an electric heat pump and air handler. Minimum federal efficiency (14.3 SEER2, 11.7 EER2, 7.5 HSPF2) heat pumps were evaluated. Savings are compared to a new ducted natural gas furnace and AC (14.3 SEER2, 11.7 EER2, 80 AFUE).
3) High Efficiency HPSH: Replace existing ducted AC and natural gas furnace with an electric heat pump and air handler. Higher efficiency (17 SEER2, 12.48 EER2, 9.5 HSPF2) heat pumps were evaluated. Savings are compared to a new ducted natural gas furnace and AC (14.3 SEER2, 11.7 EER2, 80 AFUE).

Over the 30-year analysis period, certain changes are assumed when the equipment is replaced that impact both lifetime costs and energy use. Table 7 and Table 8 present the lifetime scenario for the DFHP Existing Furnace and HPSH measures, respectively. The analysis assumed a 20-year effective useful lifetime (EUL) for a furnace, a 15-year EUL for an air conditioner and a 15-year EUL for a heat pump. Lifetimes are based on the Database for Energy Efficient Resources (DEER) (California Public Utilities Commission, 2021b). The existing furnace is assumed to be halfway through its EUL at the beginning of the analysis period. After 10 years when the furnace reaches the end of its life and needs to be replaced, it will be subject to new federal efficiency standards for residential gas furnaces that go into effect in 2028 requiring 95 AFUE

6. Five years later the air conditioner reaches the end of its life and is replaced with a new air conditioner.

6 https://www.energy.gov/articles/doe-finalizes-energy-efficiency-standards-residential-furnaces-save- americans-15-
billion#:~:text=These%20furnace%20efficiency%20standards%20were,heat%20for%20the%20livin g%20space.

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For the DFHP upgrade case, after 10 years when the furnace fails it’s expected that the furnace is abandoned in place since the heat pump serves primary heating and was sized to provide the full design heating load. In this case it is assumed that the fan motor is replaced with a new aftermarket unit and operates another five years until the heat pump fails and is replaced with a new heat pump and air handler. Table 7 through Table 8 present the lifecycle incremental cost breakdown for a 4-ton system. The heat pump is sized for each climate zone based on the heating and cooling load as shown in Table 4, and the 4-ton system was selected as an example to show the lifecycle cost breakdown.

Table 7. Lifecycle Incremental Cost Breakdown for a 4-Ton DFHP Existing Furnace Calendar
Year
Baseline AC
Replacement
Schedule
Baseline
Future
Cost
Baseline
Present
Value
Cost
Heat Pump
Heat
Pump
Future
Cost
Heat
Pump
Present
Value
Cost
2026 AC fails, install new
AC, keep existing
furnace
$10,431 $10,431 AC fails, install new
HP , keep existing
furnace
$12,347 $12,347
2036 Furnace fails, install
new 95AFUE
furnace
$7,879 $5,863 Furnace fails,
replace fan motor
$1,200 $893
2041 AC fails, install new
AC
$10,431 $6,695 HP fails, install new
HP and air handler
$14,529 $9,326
Total $22,989 $22,566
Incremental Cost -$424

Table 8. Lifecycle Incremental Cost Breakdown for 4-Ton HPSH Calendar
Year
Baseline AC
Replacement
Schedule
Baseline Future
Cost
Baseline
Present
Value
Cost
Heat Pump
Heat Pump
Future
Cost
Heat
Pump
Present
Value
Cost
2026 AC fails, install
new AC &
furnace
$13,808 $13,808 AC fails,
install new

HP & AHU
$14,529 $14,529
2041 AC fails, install
new AC
$10,431 $6,695 HP fails,
install new

HP & AHU
$13,529 $8,684
2046 Furnace fails,
install new
95AFUE
furnace
$7,879 $4,363
- - -
2056 Remaining
useful life for
furnace
- -$1,623
- - -
Total $23,243 $23,213
Incremental Cost -$30

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Table 9 presents estimated first and lifetime costs for the baseline and heat pump scenarios for 4-ton equipment. Costs include all material and installation labor including providing new 240 V electrical service to the air handler location for all new air handler installations and decommissioning of the furnace for the cases where the furnace is removed. DFHP costs incorporate controls installation and commissioning to ensure the heat pump and the furnace communicate properly and don’t operate at the same time. Future replacement costs do not include any initial costs associated with 240V electrical service or furnace decommissioning.

Table 9. HVAC Measure Cost Assumptions – 4-Ton Electric Replacements Measure Case
AC +
Evaporator
Coil
Gas
Furnace
/AC
DFHP Existing
Furnace HPSH
High
Efficiency
HPSH
Base Case - - AC +
Evaporator Coil
Gas
Furnace
/AC
Gas
Furnace
/AC
First Cost $10,431 $13,808 $12,347 $14,529 $17,506
Replacement Cost
(Future Value) $18,310 $18,310 $15,729 $13,529 $16,506
Replacement Cost
(Present Value) $12,558 $11,058 $10,219 $8,684 $10,594
Remaining Value at
Year 30 $0 -$1,623 $0 $0 $0
Total Lifecycle Cost $22,989 $23,243 $22,566 $23,213 $28,100 Incremental Cost - - -$424 -$30 $4,857

2.4.1 Lifecycle Cost Assuming Zero-NOx Standards for Space Heating After 2030
The California Air Resource Board proposed a strategy for reducing emissions in their 2022 Scoping Plan for Achieving Carbon Neutrality that includes a zero-emission standard for space and water heaters sold in California that would go into effect in 2030 (California Air Resources Board, 2022).

The South Coast Air Quality Management District (SCAQMD) proposed Rule 1111 for the Reduction of NOx Emissions from Natural Gas-Fired Furnaces. This rule applies to furnaces less than 175,000 Btu/hr and sets compliance goals for manufacturers with the proposed dates in Table 10. The sale of gas furnaces above the compliance target will incur a mitigation fee (SCAQMD, 2025).

Table 10. SCAQMD Rule 1111 Proposed Manufacturer Compliance Targets Target Dates 2027-2028 2029-2032 2033-2035 2036 and after NOx Emitting Units (e.g. gas) 70% 50% 25% 10%
Zero-Emission Units 30% 50% 75% 90%

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The Bay Area Air Quality Management District (BAAD) adopted Rule 9-4 that similarly requires zero NOx standards for space heating systems sold in the Bay Area.

Implementation for residential furnaces will begin January 2029 (BAAD, 2025).

The BAAD Rule 9-4 has been adopted, but both the California Air Resources Board and SCAQMD Rule 1111 are proposed rules that have not yet been adopted, but given the implications these rulings would have on the 30-year cost-effectiveness if gas furnaces were very limited or no longer available in 2030, a sensitivity analysis for this scenario is included in this study for the DFHP Existing Furnace scenario. The other heat pump measures would also be impacted by this ruling; however, for simplicity the team selected one measure to give a sense of the impact on the results. The following costs reflect the scenario where gas furnaces are not available in 2030. This 30-year lifecycle analysis assumes that in 10 years when the furnace reaches the end of its useful life and needs to be replaced, it will be subjected to the SCAQMD Rule 1111 or California Air Resources Board proposal and will be replaced with a heat pump.

Table 11. Lifecycle Incremental Cost Breakdown for 4-Ton System with no Gas Furnaces after 2030
Calendar
Year
Baseline AC
Replacement
Schedule
Baseline
Future
Cost
Baseline
Present
Value
Cost
Heat Pump
Heat
Pump
Future
Cost
Heat
Pump
Present
Value
Cost
2026
AC fails, install new
AC, keep existing
furnace
$10,431 $10,431
AC fails, install new
HP , keep existing
furnace
$12,347 $12,347
2036 Furnace fails, install
new HP $14,529 $10,811 Furnace fails,
replace fan motor $1,200 $893
2041 - - - HP fails, install new
HP and air handler $14,529 $9,326
2051 HP fails, install new
HP $13,529 $6,462 - - -
2056 Remaining useful
life for HP - -$4,459 - - -
Total $23,244 $22,566
Incremental Cost -$679

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3 Results
The primary objective of the evaluation is to identify cost-effective HPSH upgrade measures for existing single family buildings, to support the design of local ordinances encouraging installation of a heat pump when replacing an air conditioner. While this section focuses primarily on the results of the cost-effectiveness analysis, it is important to highlight that the associated greenhouse gas (GHG) emissions savings are significant – averaging a 25% annual reduction across the climate zones and vintages. A full dataset of all results, including site energy, source energy, LSC and GHG emissions, can be downloaded at https://localenergycodes.com/content/resources. Results alongside policy options can also be explored using the Cost-effectiveness Explorer at https://explorer.localenergycodes.com/.

3.1 Cost-Effectiveness Results
Table 12 through Table 14 present results across the 16 climate zones for the 1992-2010 vintage using standard tariffs and Table 15 through Table 17 present results across the 16 climate zones and three vintages using CARE tariffs. Results show the incremental cost and utility bill savings for the first year along with cost effectiveness results for LSC and On-Bill under both the modest and high gas escalation scenarios. Results for additional vintages using standard tariffs are in Appendix 6.2 Cost-Effectiveness Results.

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3.1.1 Cost Effectiveness Results Using Standard Tariffs Table 12. [1992-2010] DFHP Existing Furnace
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $2,405 $60 $10,843 $5,471 $21,616
CZ02 PGE $1,670 ($86) $8,462 $2,312 $12,767
CZ03 PGE $1,178 $15 $8,302 $4,810 $13,877
CZ04 PGE $1,670 ($68) $7,396 $1,955 $10,123
CZ04 CPAU $1,670 ($9) $7,396 $2,207 $7,179
CZ05 PGE $1,424 ($12) $6,848 $3,425 $11,150
CZ05 PGE/SCG $1,424 ($195) $6,848 ($1,864) $2,099
CZ06 SCE/SCG $1,424 ($34) $2,647 $675 $1,468
CZ07 SDGE $1,424 ($36) $2,691 $599 $1,734
CZ08 SCE/SCG $1,916 ($65) $2,028 ($662) $311
CZ09 SCE/SCG $1,916 ($90) $2,749 ($1,037) $437
CZ10 SCE/SCG $1,916 ($79) $2,444 ($833) $543
CZ10 SDGE $1,916 $54 $2,444 $2,350 $4,857
CZ11 PGE $2,162 $68 $7,672 $4,713 $14,750
CZ12 PGE $1,916 $44 $8,466 $4,851 $15,371
CZ12 SMUD/PGE $1,916 $353 $8,466 $11,771 $22,513
CZ13 PGE $2,162 $76 $5,318 $3,972 $11,212
CZ14 SCE/SCG $1,916 ($179) $4,803 ($2,215) $1,489
CZ14 SDGE $1,916 ($22) $4,803 $1,431 $7,207
CZ15 SCE/SCG $2,408 ($133) ($122) ($3,289) ($3,060)
CZ16 PGE $2,243 ($66) $8,842 $1,260 $11,982

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Table 13. [1992-2010] Standard Efficiency HPSH
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $3,067 ($145) $10,949 ($34) $17,899
CZ02 PGE $652 ($229) $9,362 ($702) $11,825
CZ03 PGE $514 ($62) $8,244 $2,373 $11,665
CZ04 PGE $652 ($205) $8,680 ($572) $10,753
CZ04 CPAU $652 ($85) $8,680 $556 $7,194
CZ05 PGE $583 ($113) $6,957 $752 $9,206
CZ05 PGE/SCG $583 ($316) $6,957 ($5,101) ($811)
CZ06 SCE/SCG $583 ($37) $2,134 ($63) $716
CZ07 SDGE $583 ($39) $2,156 ($149) $981
CZ08 SCE/SCG $721 ($79) $1,812 ($1,356) ($371)
CZ09 SCE/SCG $721 ($118) $2,589 ($2,038) ($524)
CZ10 SCE/SCG $721 ($103) $2,311 ($1,723) ($259)
CZ10 SDGE $721 $34 $2,311 $1,533 $4,218
CZ11 PGE $790 ($35) $8,817 $2,833 $14,504
CZ12 PGE $721 ($94) $9,199 $1,812 $13,563
CZ12 SMUD/PGE $721 $363 $9,199 $12,027 $24,107
CZ13 PGE $790 $6 $5,948 $2,558 $10,687
CZ14 SCE/SCG $721 ($412) $6,635 ($6,964) ($1,073)
CZ14 SDGE $721 ($107) $6,635 $166 $10,249
CZ15 SCE/SCG $859 ($139) ($112) ($3,434) ($3,186)
CZ16 PGE $2,095 ($385) $13,600 ($2,842) $19,424

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Table 14. [1992-2010] High Efficiency HPSH
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $5,998 $56 $9,783 ($350) $17,727
CZ02 PGE $3,606 ($94) $7,527 ($2,544) $10,080
CZ03 PGE $3,422 $59 $5,701 $312 $9,692
CZ04 PGE $3,606 ($61) $6,961 ($2,193) $9,235
CZ04 CPAU $3,606 $0 $6,961 ($2,389) $4,310
CZ05 PGE $3,514 $4 $4,176 ($1,450) $7,088
CZ05 PGE/SCG $3,514 ($199) $4,176 ($7,303) ($2,929)
CZ06 SCE/SCG $3,514 ($14) ($2,162) ($4,367) ($3,567)
CZ07 SDGE $3,514 ($12) ($2,090) ($4,312) ($3,191)
CZ08 SCE/SCG $3,698 $13 ($1,660) ($4,217) ($3,149)
CZ09 SCE/SCG $3,698 ($26) ($750) ($4,883) ($3,284)
CZ10 SCE/SCG $3,698 ($4) ($844) ($4,418) ($2,864)
CZ10 SDGE $3,698 $132 ($844) ($1,068) $1,587
CZ11 PGE $3,789 $186 $7,738 $2,845 $14,675
CZ12 PGE $3,698 $88 $7,575 $996 $12,879
CZ12 SMUD/PGE $3,698 $422 $7,575 $8,459 $20,580
CZ13 PGE $3,789 $208 $4,419 $2,165 $10,439
CZ14 SCE/SCG $3,698 ($219) $5,760 ($7,575) ($1,506)
CZ14 SDGE $3,698 $77 $5,760 ($424) $9,604
CZ15 SCE/SCG $3,881 $50 ($2,144) ($4,209) ($3,786)
CZ16 PGE $5,071 ($97) $14,557 ($1,291) $21,181

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3.1.2 Cost Effectiveness Results Using CARE Tariffs
Table 15. [1992-2010] DFHP Existing Furnace CARE
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $2,405 $153 $10,843 $6,436 $19,266
CZ02 PGE $1,670 $18 $8,462 $3,916 $12,233
CZ03 PGE $1,178 $73 $8,302 $5,493 $12,696
CZ04 PGE $1,670 $14 $7,396 $3,217 $9,716
CZ04 CPAU $1,670 $0 $7,396 $786 $786
CZ05 PGE $1,424 $47 $6,848 $4,198 $10,337
CZ05 PGE/SCG $1,424 ($98) $6,848 $23 $3,191
CZ06 SCE/SCG $1,424 ($18) $2,647 $967 $1,600
CZ07 SDGE $1,424 ($16) $2,691 $1,000 $1,887
CZ08 SCE/SCG $1,916 ($38) $2,028 ($136) $644
CZ09 SCE/SCG $1,916 ($52) $2,749 ($301) $879
CZ10 SCE/SCG $1,916 ($45) $2,444 ($182) $920
CZ10 SDGE $1,916 $51 $2,444 $2,147 $4,112
CZ11 PGE $2,162 $115 $7,672 $5,068 $13,039
CZ12 PGE $1,916 $103 $8,466 $5,436 $13,792
CZ12 SMUD/PGE $1,916 $418 $8,466 $12,488 $21,071
CZ13 PGE $2,162 $100 $5,318 $4,013 $9,760
CZ14 SCE/SCG $1,916 ($98) $4,803 ($700) $2,268
CZ14 SDGE $1,916 $23 $4,803 $2,156 $6,677
CZ15 SCE/SCG $2,408 ($88) ($122) ($2,307) ($2,111)
CZ16 PGE $2,243 $33 $8,842 $2,737 $11,267

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Table 16. [1992-2010] Standard Efficiency HPSH CARE
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $3,067 $33 $10,949 $2,703 $16,973
CZ02 PGE $652 ($59) $9,362 $2,211 $12,188
CZ03 PGE $514 $25 $8,244 $3,685 $11,074
CZ04 PGE $652 ($53) $8,680 $2,048 $11,067
CZ04 CPAU $652 $0 $8,680 $255 $255
CZ05 PGE $583 ($13) $6,957 $2,389 $9,117
CZ05 PGE/SCG $583 ($173) $6,957 ($2,232) $1,208
CZ06 SCE/SCG $583 ($20) $2,134 $249 $872
CZ07 SDGE $583 ($18) $2,156 $279 $1,161
CZ08 SCE/SCG $721 ($47) $1,812 ($728) $62
CZ09 SCE/SCG $721 ($70) $2,589 ($1,094) $122
CZ10 SCE/SCG $721 ($61) $2,311 ($892) $281
CZ10 SDGE $721 $39 $2,311 $1,509 $3,612
CZ11 PGE $790 $60 $8,817 $4,141 $13,421
CZ12 PGE $721 $22 $9,199 $3,592 $12,940
CZ12 SMUD/PGE $721 $471 $9,199 $13,622 $23,292
CZ13 PGE $790 $61 $5,948 $3,234 $9,693
CZ14 SCE/SCG $721 ($241) $6,635 ($3,632) $1,098
CZ14 SDGE $721 ($5) $6,635 $1,996 $9,885
CZ15 SCE/SCG $859 ($91) ($112) ($2,414) ($2,201)
CZ16 PGE $2,095 ($92) $13,600 $2,163 $19,892

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Table 17. [1992-2010] High Efficiency HPSH CARE
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $5,998 $164 $9,783 $813 $15,177
CZ02 PGE $3,606 $28 $7,527 ($683) $9,357
CZ03 PGE $3,422 $104 $5,701 $674 $8,120
CZ04 PGE $3,606 $41 $6,961 ($703) $8,383
CZ04 CPAU $3,606 $0 $6,961 ($4,595) ($4,595)
CZ05 PGE $3,514 $62 $4,176 ($727) $6,056
CZ05 PGE/SCG $3,514 ($98) $4,176 ($5,348) ($1,853)
CZ06 SCE/SCG $3,514 ($5) ($2,162) ($4,219) ($3,583)
CZ07 SDGE $3,514 ($0) ($2,090) ($4,112) ($3,235)
CZ08 SCE/SCG $3,698 $15 ($1,660) ($4,248) ($3,401)
CZ09 SCE/SCG $3,698 ($8) ($750) ($4,603) ($3,330)
CZ10 SCE/SCG $3,698 $6 ($844) ($4,300) ($3,065)
CZ10 SDGE $3,698 $103 ($844) ($1,892) $191
CZ11 PGE $3,789 $203 $7,738 $2,425 $11,808
CZ12 PGE $3,698 $141 $7,575 $1,351 $10,784
CZ12 SMUD/PGE $3,698 $471 $7,575 $8,735 $18,405
CZ13 PGE $3,789 $192 $4,419 $1,255 $7,809
CZ14 SCE/SCG $3,698 ($111) $5,760 ($5,632) ($783)
CZ14 SDGE $3,698 $115 $5,760 ($98) $7,755
CZ15 SCE/SCG $3,881 $36 ($2,144) ($4,549) ($4,220)
CZ16 PGE $5,071 $95 $14,557 $1,460 $19,324

3.2 Zero-NOx Scenario Results
This section presents cost-effectiveness results for the DFHP Existing Furnace under the scenario where proposed air quality district zero-NOx rules go into effect over the next 10 years. In the base case, at time of replacement of the gas furnace at year 10 a heat pump is installed. The energy profile between the base case and the heat pump upgrade case are subsequently identical for the remaining 20 years of the 30-year analysis period. As a result, energy and cost savings only persist for the first 10 years.

Table 18 shows the On-Bill NPV cost-effectiveness results assuming high gas escalation.

The high gas escalation was used for the zero-NOx analysis because the high gas escalation is built on the assumption that gas furnaces are no longer available to be installed due to zero-NOx regulations or similar policies. Table 19 shows the LSC cost- effectiveness results for all three vintages. 2025 LSC savings were calculated using individual year multipliers for the first 10 years, 2026 through 2035.

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Table 18. DFHP Existing Furnace On-Bill NPV with High Gas Escalation (Zero-NOx Rule) Climate
Zone
Electric/
Gas Utility
On-Bill NPV
Pre-1978 1978-1991 1992-2010
CZ01 PGE $5,473 $4,136 $2,349
CZ02 PGE $1,785 $1,031 $1,101
CZ03 PGE $2,863 $2,097 $2,052
CZ04 PGE $2,133 $1,162 $1,019
CZ04 CPAU $2,340 $1,599 $1,213
CZ05 PGE $1,918 $1,486 $1,576
CZ05 PGE/SCG ($1,308) ($834) ($491)
CZ06 SCE/SCG $401 $605 $635
CZ07 SDGE $1,473 $999 $641
CZ08 SCE/SCG ($125) $99 $195
CZ09 SCE/SCG ($563) ($183) $22
CZ10 SCE/SCG ($259) $53 $110
CZ10 SDGE $2,985 $2,261 $1,430
CZ11 PGE $3,287 $2,866 $2,279
CZ12 PGE $2,935 $2,578 $2,202
CZ12 SMUD/PGE $7,877 $5,978 $5,040
CZ13 PGE $2,927 $2,556 $2,053
CZ14 SCE/SCG ($864) ($943) ($543)
CZ14 SDGE $2,204 $1,655 $1,064
CZ15 SCE/SCG $1,338 $396 ($688)
CZ16 PGE $1,192 $1,071 $1,096

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Table 19. DFHP Existing Furnace LSC Savings (Zero-NOx Rule)

Climate
Zone

Electric/
Gas Utility

LSC NPV
Pre-1978 1978-1991 1992-2010
CZ01 PGE $3,019 $2,510 $1,558
CZ02 PGE $1,256 $1,025 $1,006
CZ03 PGE $1,460 $1,120 $1,036
CZ04 PGE $1,242 $949 $887
CZ04 CPAU $1,242 $949 $887
CZ05 PGE $1,127 $816 $820
CZ05 PGE/SCG $1,127 $816 $820
CZ06 SCE/SCG $545 $318 $251
CZ07 SDGE $639 $403 $314
CZ08 SCE/SCG $428 $279 $244
CZ09 SCE/SCG $608 $424 $372
CZ10 SCE/SCG $469 $320 $293
CZ10 SDGE $469 $320 $293
CZ11 PGE $1,871 $1,475 $1,263
CZ12 PGE $1,924 $1,539 $1,356
CZ12 SMUD/PGE $1,375 $1,090 $939
CZ13 PGE ($206) ($186) $50
CZ14 SCE/SCG ($206) ($186) $50
CZ14 SDGE $127 $60 $38
CZ15 SCE/SCG ($185) ($12) $77
CZ16 PGE $3,019 $2,510 $1,558

3.3 AC Pathways for Heat Pump Replacements
Many jurisdictions are interested in seeing alternative pathways for residents who may prefer to replace an air conditioner with similar equipment, rather than migrating to a heat pump system. Alternative packages analyzed to support this request include air conditioning equipment combined with additional efficiency measures resulting in options that are reasonably energy or LSC cost equivalent to a heat pump system, to the extent feasible.

Figure 1 shows two AC pathways, one with an existing duct system and another path with a new duct system, alongside the heat pump pathways. The figure presents the proposed efficiency upgrade measures that would be part of a reach code (solid blue) along with the relevant requirements from Title 24, Part 6 that are triggered as part of equipment replacements (white or gradient blue). A reach code that establishes requirements when an air conditioner is replaced or installed new could allow for either a heat pump to be installed or an AC as long as the performance measures listed below are met.

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Figure 1. AC vs. Heat Pump Pathway Requirements

The heat pump only and two AC pathways are presented in Figure 2 comparing total LSC energy use relative to the existing home for the 1992-2010 vintage. The heat pump path is represented by the DFHP Existing Furnace scenario. In most climate zones, the heat pump path results in higher energy savings, in the milder climates the AC and new ducts and New AC Only paths save marginally more energy.

Figure 2. AC vs. Heat Pump Energy Comparison

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Though the AC path does not need to meet cost-effectiveness criteria to be adopted as a reach code since it’s an alternative path, in order to understand the implications of the AC path on the customer, Table 20 and Table 21 present estimated costs for the new AC only and the new AC + new ducts paths respectively.

Table 20. New AC Only Path Cost Estimates
New AC Only Path Pre-1978 1978-1991 1992-2010
Fan Efficacy: 0.45 W/CFM - - -
Refrigerant Charge Verification $100 $100 $1007
R-49 Attic Insulation $5,483 $3,612 $1,827
Air Sealing $1,963 $1,963 $1,963
Total $7,546 $5,675 $3,790

Table 21. New AC/Furnace and New Ducts Path Cost Estimates New AC and New Ducts Path Pre-1978 1978-1991 1992-2010
New R-8 Ducts $6,311 $6,311 $6,311
Furnace $5,951 $5,951 $5,951
Fan Efficacy: 0.35 W/CFM $500 $500 $500
Refrigerant Charge Verification $100 $100 $100
Total $12,862 $12,862 $12,862

7 This is an incremental cost and in some climate zones, refrigerant charge verification is required so there is no incremental cost added.

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4 Recommendations and Discussion
This analysis evaluated the feasibility and cost-effectiveness of AC to heat pump measures in California existing homes built before 2010. To meet the needs of jurisdictions evaluating this option, Statewide Reach Codes Team used both On-Bill and LSC-based lifecycle cost approaches to evaluate cost-effectiveness and quantify the energy cost savings associated with energy efficiency measures compared to the incremental costs associated with the measures.

Conclusions and Discussion:

1. Heat pumps are significantly more efficient than gas furnaces, requiring less than half the energy to meet the heating load. However, despite this reduction in heating energy use, the cost of heating a home using electricity (heat pump) could be higher than the cost to heat that same home with natural gas (furnace), depending on the electricity tariffs relative to the gas tariffs. Therefore, while a heat pump measure could be deemed as cost-effective over its lifecycle, installing a heat pump could result in a decrease or an increase in utility costs in the first years relative to a gas furnace and AC system. For example, the heat pump space heater measure in climate zone 12 in the newest vintage results in the customer saving money on their utility bill in SMUD territory but paying more on their utility bill in PG&E territory. Both PG&E and SMUD territory use PG&E gas rates, but SMUD has lower electricity rates than PG&E. With fuel switching measures like the AC to HP measure, the electricity to gas ratio has a significant impact on the savings or costs the customer will see by switching from gas to an electric heat pump space heater.

2. The LSC metric most often produces more favorable cost-effectiveness results relative to the results produced using actual utility costs (On-Bill). When the analysis assumes a higher escalation rate for natural gas costs relative to electricity in future years (high gas escalation), the On-Bill results are more favorable in some cases. a. In the oldest (pre-1978) vintage, all three measures (dual fuel heat pump with existing furnace, standard heat pump space heater, and high efficiency heat pump space heater) are cost-effective using the LSC metric in all climate zones. When using the On-Bill metric, the measures remain cost-effective in most climate zones.
b. In the newer (1978-1991 and 1992-2010) vintages, the dual fuel heat pump (DFHP Existing Furnace) and the standard efficiency HPSH are cost-effective based on LSC in all cases except for Climate Zone 15 when using both the standard and California Alternative Rates for Energy (CARE) tariff.

3. Using the CARE tariff results in higher cost savings and cost-effectiveness relative to standard rates, with almost all cases yielding first year utility cost savings. The DFHP Existing Furnace is On-Bill cost-effective based on the high gas escalation scenario in all cases in the pre-1978 vintage, and almost all cases in the 1978-1991 and 1992-2010 vintage. It is also On-Bill cost-effective in most climate zones for the Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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modest gas escalation scenario across all vintages. In Climate Zones 5, 8, 9, 10, 14, and 15, cost-effectiveness declines relative to other areas, and in some cases is not cost-effective from an On-Bill perspective. This is the case for both the CARE tariff and the standard rate.

4. The analysis also modeled the cost impact of using a standard time-of-use electricity tariff versus switching to a newer electrification tariff, designed to reduce costs in homes with heat pumps and/or electric vehicles. Older homes tend to be the least efficient and achieve the most savings from improving equipment efficiency. In most of the state, because older homes tend to use more electricity than a similarly sized, newer vintage home, they realize more costs savings under the electrification tariff.

Newer homes tend to use less electricity and therefore do not realize the same cost savings from switching tariffs; they generally perform better under the standard tariff.

This trend is different in milder climate zones in SCE territory (excluding CZ 15), where newer homes realize more cost savings than older homes. Both the standard and electrification tariffs in SCE territory include a daily allocation of lower-cost baseline electricity and a second, higher-priced tier when the baseline is exceeded.

In many newer homes, a higher percentage of overall electricity use is within the baseline allocation, resulting in greater cost savings.

5. Higher efficiency equipment reduces utility costs in all cases and improves cost- effectiveness in many climate zones in the oldest vintage relative to standard efficiency equipment. However, in more efficient newer homes, where cost- effectiveness is generally lower, the savings are insufficient to offset the roughly $3,000 increase in incremental cost.

6. Given the adopted Bay Area Air Quality Management District Zero NOx rule, and the proposed California Air Resource Board or South Coast Air Quality Management District (SCAQMD) Zero-NOx rules, and gas furnaces may not be available to be installed in 2030, a sensitivity analysis was performed for the Zero NOx scenario and found that cost-effectiveness decreases in many cases except in Climate Zone 15.

The improved cost-effectiveness is due to the higher baseline cost when HPSH must be installed at year 10 when the furnace must be replaced. It is also important to note that Climate Zone 15 is the only climate zone that utilizes a 5-ton HPSH, which has a much higher cost than the smaller sized systems, resulting in cost- effectiveness improvements under the Zero-Nox rules.

7. While not evaluated in this report, the 2022 Single Family Retrofit Cost-effectiveness Study (Statewide Reach Codes Team, 2024) shows it is beneficial to combine a heat pump space conditioning system with photovoltaics (PV) because the additional electricity required by the heat pump can be met by the PV system and result in reduced utility bills.

8. In this study the dual fuel heat pump is evaluated with an existing furnace, however the homeowner could choose to replace the existing furnace with a new furnace at this time as well. This measure (DFHP New Furnace) was evaluated in the 2022 Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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Single Family Retrofit Cost-effectiveness Study (Statewide Reach Codes Team, 2024) but found to be less cost-effective than the DFHP Existing Furnace case.

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5 References
BAAD. (2025, May 7). Rules 9-4 and 9-6 Building Appliances. Retrieved from Bay Area Air District: https://www.baaqmd.gov/en/rules-and-compliance/rule- development/building-appliances
California Air Resources Board. (2022, August 12). 2022 State Strategy for the State Implementation Plan (2022 State SIP Strategy). Retrieved from California Air Resources Board Web site: https://ww2.arb.ca.gov/sites/default/files/2022- 11/Proposed_2022_State_SIP_Strategy.pdf
California Energy Commission. (2017). Rooftop Solar PV System. Measure number: 2019- Res-PV-D Prepared by Energy and Environmental Economics, Inc. Retrieved from https://efiling.energy.ca.gov/getdocument.aspx?tn=221366 California Energy Commission. (2021b). Final Express Terms for the Proposed Revisions to the 2022 Energy Code Reference Appendices. Retrieved from https://efiling.energy.ca.gov/Lists/DocketLog.aspx?docketnumber=21-BSTD-01 California Energy Commission. (2023). 2025 Energy code Hourly Factors. Retrieved from https://www.energy.ca.gov/files/2025-energy-code-hourly-factors California Energy Commission. (2023). Draft 2025 Energy Code Express Terms. Retrieved from
https://efiling.energy.ca.gov/GetDocument.aspx?tn=252915&DocumentContentId=88 051
California Energy Commission. (2025). Final Express Terms for the Proposed Revisions to 2025 Title 24, Part 11 (CALGreen). Retrieved from
https://efiling.energy.ca.gov/GetDocument.aspx?tn=261229&DocumentContentId=97 592
California Public Utilities Commission. (2021a). Utility Costs and Affordability of the Grid of the Future: An Evaluation of Electric Costs, Rates, and Equity Issues Pursuant to P.U. Code Section 913.1. Retrieved from https://www.cpuc.ca.gov/-/media/cpuc- website/divisions/office-of-governmental-affairs-division/reports/2021/senate-bill-695- report-2021-and-en-banc-whitepaper_final_04302021.pdf
California Public Utilities Commission. (2021b). Database for Energy-Efficient resources (DEER2021 Update). Retrieved April 13, 2021, from
http://www.deeresources.com/index.php/deer-versions/deer2021 Department of Energy. (2023). DOE Finalizes Energy Efficiency Standards for Residential Furnaces to Save Americans $1.5 Billion In Annual Utility Bills. Retrieved from www.energy.gov: https://www.energy.gov/articles/doe-finalizes-energy-efficiency- standards-residential-furnaces-save-americans-15-billion Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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E-CFR. (2020). https://www.ecfr.gov/cgi-
bin/retrieveECFR?gp=&SID=8de751f141aaa1c1c9833b36156faf67&mc=true&n=pt1

0.3.431&r=PART&ty=HTML#se10.3.431_197. Retrieved from Electronic Code of Federal Regulations: https://www.ecfr.gov/cgi-
bin/retrieveECFR?gp=&SID=8de751f141aaa1c1c9833b36156faf67&mc=true&n=pt1

0.3.431&r=PART&ty=HTML#se10.3.431_197
Heinemeier, K. (2025). Residential HVAC Performance. Retrieved from https://title24stakeholders.com/wp-content/uploads/2025/03/Residential-HVAC- Performance.pdf
SCAQMD. (2025). Proposed Amended Rules (PAR) 1111 and 1121. Retrieved from aqmd.gov.

SCAQMD. (2025, February 21). Space and Water Heating Building Appliances. Retrieved from South Coast AQMD: https://www.aqmd.gov/docs/default- source/Agendas/ssc/ssc-agenda-2-21-2025.pdf
Statewide CASE Team. (2023). Multifamily Domestic Hot Water. Retrieved from https://title24stakeholders.com/wp-content/uploads/2023/08/2025_T24_CASE- Report-_MF-DHW-Final-1.pdf
Statewide CASE Team. (2023). Residential HVAC PErformance. Retrieved from https://title24stakeholders.com/wp-
content/uploads/2023/11/Revised_2025_T24_Final-CASE-Report-RES-HVAC- Performance.pdf
Statewide Reach Codes Team. (2021). 2019 Cost-Effectiveness Study: Existing Single Family Residential Buidling Upgrades. Retrieved from
https://localenergycodes.com/content/resources
Statewide Reach Codes Team. (2024). 2022 Cost-Effectiveness Study: Existing Single Family Building Upgrades. Prepared by Frontier Energy. Retrieved from https://localenergycodes.com/download/1222/file_path/fieldList/Single%20Family%2 0Retrofits%20CostEff%20Report.pdf

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6 Appendices

6.1 Map of California Climate Zones
Climate zone geographical boundaries are depicted in Figure 3. The map in Figure 3 along with a zip-code search directory is available at:
https://ww2.energy.ca.gov/maps/renewable/building_climate_zones.html Figure 3. Map of California climate zones.

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6.2 Cost-Effectiveness Results

6.2.1 Standard Rates
The following tables present results across the 16 climate zones for the pre-1978 (Table 22 through Table 24) and the 1978-1991 (Table 25 through Table 27) vintages supplementing the results in Section 3.

Table 22. [Pre-1978] DFHP Existing Furnace
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $2,405 $155 $25,223 $14,524 $51,831
CZ02 PGE $1,670 ($81) $11,625 $4,391 $20,880
CZ03 PGE $1,178 $39 $11,599 $7,167 $21,825
CZ04 PGE $1,670 ($7) $10,648 $5,023 $18,395
CZ04 CPAU $1,670 $63 $10,648 $5,251 $14,605
CZ05 PGE $1,424 ($29) $9,462 $4,574 $16,955
CZ05 PGE/SCG $1,424 ($314) $9,462 ($3,674) $2,838
CZ06 SCE/SCG $1,424 ($70) $4,223 $179 $1,795
CZ07 SDGE $1,424 $41 $4,278 $2,725 $5,055
CZ08 SCE/SCG $1,916 ($111) $3,365 ($1,358) $524
CZ09 SCE/SCG $1,916 ($168) $4,387 ($2,351) $274
CZ10 SCE/SCG $1,916 ($133) $3,904 ($1,625) $923
CZ10 SDGE $1,916 $201 $3,904 $6,324 $10,832
CZ11 PGE $2,162 $93 $12,045 $7,668 $25,025
CZ12 PGE $1,916 $46 $12,451 $7,097 $24,339
CZ12 SMUD/PGE $1,916 $584 $12,451 $19,146 $36,775
CZ13 PGE $2,162 $112 $8,254 $6,448 $18,815
CZ14 SCE/SCG $1,916 ($244) $6,795 ($2,777) $3,481
CZ14 SDGE $1,916 $65 $6,795 $4,352 $13,446
CZ15 SCE/SCG $2,408 $80 $550 $1,655 $2,681
CZ16 PGE $2,243 ($199) $17,538 $2,333 $25,276

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Table 23. [Pre-1978] Standard Efficiency HPSH
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $3,067 ($127) $27,155 $7,800 $48,445
CZ02 PGE $652 ($242) $13,342 $1,420 $21,282
CZ03 PGE $514 ($46) $11,946 $4,614 $19,670
CZ04 PGE $652 ($139) $13,059 $3,274 $21,888
CZ04 CPAU $652 ($48) $13,059 $3,194 $15,372
CZ05 PGE $583 ($131) $9,998 $2,045 $15,648
CZ05 PGE/SCG $583 ($449) $9,998 ($7,152) ($94)
CZ06 SCE/SCG $583 ($76) $3,860 ($652) $931
CZ07 SDGE $583 $35 $3,876 $1,901 $4,218
CZ08 SCE/SCG $721 ($128) $3,305 ($2,112) ($199)
CZ09 SCE/SCG $721 ($219) $4,415 ($3,839) ($1,141)
CZ10 SCE/SCG $721 ($188) $3,982 ($3,168) ($483)
CZ10 SDGE $721 $166 $3,982 $5,200 $10,049
CZ11 PGE $790 ($74) $14,045 $4,727 $24,836
CZ12 PGE $721 ($179) $13,850 $2,374 $21,622
CZ12 SMUD/PGE $721 $601 $13,850 $19,845 $39,654
CZ13 PGE $790 ($14) $9,394 $3,998 $17,858
CZ14 SCE/SCG $721 ($450) $10,103 ($6,294) $4,015
CZ14 SDGE $721 ($66) $10,103 $2,757 $18,994
CZ15 SCE/SCG $859 $68 $643 $1,364 $2,430
CZ16 PGE $2,095 ($484) $27,492 $2,918 $49,419

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Table 24. [Pre-1978] High Efficiency HPSH
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $5,998 $249 $30,518 $11,401 $52,316
CZ02 PGE $3,606 ($24) $13,354 $1,431 $21,449
CZ03 PGE $3,422 $100 $10,768 $3,122 $18,282
CZ04 PGE $3,606 $118 $13,537 $4,185 $22,984
CZ04 CPAU $3,606 $101 $13,537 $1,665 $13,950
CZ05 PGE $3,514 $10 $8,416 $384 $14,087
CZ05 PGE/SCG $3,514 ($308) $8,416 ($8,814) ($1,654)
CZ06 SCE/SCG $3,514 $3 $380 ($3,709) ($2,052)
CZ07 SDGE $3,514 $114 $430 ($1,063) $1,230
CZ08 SCE/SCG $3,698 $31 $1,065 ($3,478) ($1,420)
CZ09 SCE/SCG $3,698 ($40) $2,358 ($4,759) ($1,897)
CZ10 SCE/SCG $3,698 $6 $2,191 ($3,746) ($882)
CZ10 SDGE $3,698 $344 $2,191 $4,481 $9,276
CZ11 PGE $3,789 $283 $15,614 $7,801 $28,167
CZ12 PGE $3,698 $152 $14,490 $4,899 $24,385
CZ12 SMUD/PGE $3,698 $708 $14,490 $17,350 $37,236
CZ13 PGE $3,789 $326 $10,164 $6,697 $20,802
CZ14 SCE/SCG $3,698 ($173) $11,876 ($5,041) $5,522
CZ14 SDGE $3,698 $244 $11,876 $5,111 $21,254
CZ15 SCE/SCG $3,881 $335 $393 $2,323 $3,635
CZ16 PGE $5,071 $45 $34,043 $9,856 $56,737

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Table 25. [1978-1991] DFHP Existing Furnace
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $2,405 $99 $20,184 $10,746 $40,368
CZ02 PGE $1,670 ($114) $9,216 $2,259 $14,435
CZ03 PGE $1,178 $3 $8,952 $5,020 $15,543
CZ04 PGE $1,670 ($68) $8,234 $2,394 $11,893
CZ04 CPAU $1,670 $18 $8,234 $3,236 $9,492
CZ05 PGE $1,424 ($32) $7,070 $3,268 $11,902
CZ05 PGE/SCG $1,424 ($238) $7,070 ($2,666) $1,747
CZ06 SCE/SCG $1,424 ($39) $2,941 $614 $1,557
CZ07 SDGE $1,424 $1 $3,046 $1,512 $2,837
CZ08 SCE/SCG $1,916 ($78) $2,294 ($877) $294
CZ09 SCE/SCG $1,916 ($116) $3,127 ($1,506) $271
CZ10 SCE/SCG $1,916 ($89) $2,755 ($947) $720
CZ10 SDGE $1,916 $139 $2,755 $4,470 $7,469
CZ11 PGE $2,162 $103 $9,192 $6,313 $18,851
CZ12 PGE $1,916 $60 $9,753 $5,919 $18,655
CZ12 SMUD/PGE $1,916 $430 $9,753 $14,208 $27,211
CZ13 PGE $2,162 $111 $6,312 $5,317 $14,322
CZ14 SCE/SCG $1,916 ($230) $5,080 ($3,128) $1,188
CZ14 SDGE $1,916 $35 $5,080 $2,942 $9,420
CZ15 SCE/SCG $2,408 ($17) $50 ($658) ($161)
CZ16 PGE $2,243 ($161) $14,397 $1,740 $20,318

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Table 26. [1978-1991] Standard Efficiency HPSH
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $3,067 ($128) $21,427 $5,043 $37,346
CZ02 PGE $652 ($235) $10,428 ($90) $14,711
CZ03 PGE $514 ($67) $8,999 $2,767 $13,608
CZ04 PGE $652 ($164) $9,984 $1,062 $14,605
CZ04 CPAU $652 ($66) $9,984 $1,535 $9,914
CZ05 PGE $583 ($132) $7,290 $703 $10,264
CZ05 PGE/SCG $583 ($361) $7,290 ($5,939) ($1,104)
CZ06 SCE/SCG $583 ($43) $2,450 ($151) $775
CZ07 SDGE $583 ($3) $2,539 $747 $2,065
CZ08 SCE/SCG $721 ($96) $2,111 ($1,658) ($472)
CZ09 SCE/SCG $721 ($152) $3,022 ($2,659) ($831)
CZ10 SCE/SCG $721 ($121) $2,672 ($2,017) ($239)
CZ10 SDGE $721 $114 $2,672 $3,568 $6,801
CZ11 PGE $790 ($46) $10,682 $3,545 $18,156
CZ12 PGE $721 ($110) $10,747 $2,278 $16,574
CZ12 SMUD/PGE $721 $445 $10,747 $14,697 $29,392
CZ13 PGE $790 $1 $7,141 $3,112 $13,232
CZ14 SCE/SCG $721 ($398) $7,556 ($6,191) $1,058
CZ14 SDGE $721 ($53) $7,556 $1,909 $13,834
CZ15 SCE/SCG $859 ($25) $71 ($848) ($322)
CZ16 PGE $2,095 ($445) $22,236 $708 $37,873

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Table 27. [1978-1991] High Efficiency HPSH
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $5,998 $169 $23,092 $6,895 $39,412
CZ02 PGE $3,606 ($75) $9,242 ($1,370) $13,547
CZ03 PGE $3,422 $53 $6,872 $675 $11,602
CZ04 PGE $3,606 $26 $9,114 $463 $14,143
CZ04 CPAU $3,606 $43 $9,114 ($868) $7,590
CZ05 PGE $3,514 ($16) $4,859 ($1,522) $8,122
CZ05 PGE/SCG $3,514 ($246) $4,859 ($8,164) ($3,246)
CZ06 SCE/SCG $3,514 ($1) ($1,546) ($4,024) ($3,059)
CZ07 SDGE $3,514 $47 ($1,407) ($2,879) ($1,576)
CZ08 SCE/SCG $3,698 $37 ($828) ($3,608) ($2,300)
CZ09 SCE/SCG $3,698 ($17) $232 ($4,573) ($2,623)
CZ10 SCE/SCG $3,698 $20 $82 ($3,764) ($1,856)
CZ10 SDGE $3,698 $251 $82 $1,869 $5,060
CZ11 PGE $3,789 $259 $10,685 $5,452 $20,283
CZ12 PGE $3,698 $138 $10,023 $2,954 $17,430
CZ12 SMUD/PGE $3,698 $525 $10,023 $11,609 $26,363
CZ13 PGE $3,789 $289 $6,612 $4,624 $14,951
CZ14 SCE/SCG $3,698 ($188) $7,697 ($6,429) $1,012
CZ14 SDGE $3,698 $182 $7,697 $2,525 $14,378
CZ15 SCE/SCG $3,881 $193 ($1,111) ($992) ($267)
CZ16 PGE $5,071 ($30) $26,407 $5,118 $42,581

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6.2.2 CARE tariffs
Table 28. [Pre-1978] DFHP Existing Furnace CARE
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $2,405 $364 $25,223 $16,641 $46,300
CZ02 PGE $1,670 $64 $11,625 $6,507 $19,628
CZ03 PGE $1,178 $128 $11,599 $8,167 $19,817
CZ04 PGE $1,670 $90 $10,648 $6,273 $16,909
CZ04 CPAU $1,670 $0 $10,648 $786 $786
CZ05 PGE $1,424 $69 $9,462 $5,901 $15,746
CZ05 PGE/SCG $1,424 ($157) $9,462 ($613) $4,598
CZ06 SCE/SCG $1,424 ($37) $4,223 $776 $2,067
CZ07 SDGE $1,424 $42 $4,278 $2,609 $4,434
CZ08 SCE/SCG $1,916 ($63) $3,365 ($446) $1,060
CZ09 SCE/SCG $1,916 ($97) $4,387 ($983) $1,121
CZ10 SCE/SCG $1,916 ($75) $3,904 ($511) $1,528
CZ10 SDGE $1,916 $160 $3,904 $5,112 $8,649
CZ11 PGE $2,162 $183 $12,119 $8,564 $22,361
CZ12 PGE $1,916 $152 $12,451 $8,275 $21,982
CZ12 SMUD/PGE $1,916 $686 $12,451 $20,229 $34,321
CZ13 PGE $2,162 $160 $8,329 $6,744 $16,567
CZ14 SCE/SCG $1,916 ($126) $6,795 ($630) $4,382
CZ14 SDGE $1,916 $101 $6,795 $4,679 $11,801
CZ15 SCE/SCG $2,408 $60 $550 $1,131 $1,937
CZ16 PGE $2,243 $34 $17,538 $5,963 $24,236

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Table 29. [Pre-1978] Standard Efficiency HPSH CARE
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $3,067 $205 $27,155 $12,440 $44,777
CZ02 PGE $652 ($16) $13,342 $5,095 $20,910
CZ03 PGE $514 $76 $11,946 $6,319 $18,293
CZ04 PGE $652 $41 $13,059 $6,031 $20,843
CZ04 CPAU $652 $0 $13,059 $255 $255
CZ05 PGE $583 $12 $9,998 $4,285 $15,110
CZ05 PGE/SCG $583 ($240) $9,998 ($2,978) $2,679
CZ06 SCE/SCG $583 ($42) $3,860 ($7) $1,259
CZ07 SDGE $583 $37 $3,876 $1,837 $3,652
CZ08 SCE/SCG $721 ($75) $3,305 ($1,076) $457
CZ09 SCE/SCG $721 ($131) $4,415 ($2,095) $72
CZ10 SCE/SCG $721 ($110) $3,982 ($1,649) $504
CZ10 SDGE $721 $139 $3,982 $4,305 $8,106
CZ11 PGE $790 $94 $14,045 $7,108 $23,108
CZ12 PGE $721 $20 $13,850 $5,506 $20,829
CZ12 SMUD/PGE $721 $772 $13,850 $22,326 $38,189
CZ13 PGE $790 $89 $9,394 $5,347 $16,369
CZ14 SCE/SCG $721 ($241) $10,103 ($2,418) $5,836
CZ14 SDGE $721 $62 $10,103 $4,832 $17,541
CZ15 SCE/SCG $859 $52 $643 $930 $1,769
CZ16 PGE $2,095 $16 $27,492 $10,883 $47,907

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Table 30. [Pre-1978] High Efficiency HPSH CARE
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $5,998 $450 $30,518 $13,096 $45,609
CZ02 PGE $3,606 $126 $13,354 $3,405 $19,322
CZ03 PGE $3,422 $172 $10,768 $3,678 $15,720
CZ04 PGE $3,606 $209 $13,537 $4,926 $19,859
CZ04 CPAU $3,606 $0 $13,537 ($4,595) ($4,595)
CZ05 PGE $3,514 $103 $8,416 $1,521 $12,412
CZ05 PGE/SCG $3,514 ($148) $8,416 ($5,742) ($19)
CZ06 SCE/SCG $3,514 $11 $380 ($3,634) ($2,319)
CZ07 SDGE $3,514 $89 $430 ($1,774) $25
CZ08 SCE/SCG $3,698 $33 $1,065 ($3,586) ($1,955)
CZ09 SCE/SCG $3,698 ($10) $2,358 ($4,304) ($2,027)
CZ10 SCE/SCG $3,698 $21 $2,191 ($3,628) ($1,354)
CZ10 SDGE $3,698 $255 $2,191 $2,127 $5,893
CZ11 PGE $3,789 $327 $15,614 $7,382 $23,549
CZ12 PGE $3,698 $236 $14,490 $5,437 $20,914
CZ12 SMUD/PGE $3,698 $772 $14,490 $17,439 $33,302
CZ13 PGE $3,789 $310 $10,164 $5,378 $16,558
CZ14 SCE/SCG $3,698 ($54) $11,876 ($3,161) $5,265
CZ14 SDGE $3,698 $263 $11,876 $4,651 $17,300
CZ15 SCE/SCG $3,881 $232 $393 ($35) $970
CZ16 PGE $5,071 $360 $34,043 $13,682 $50,953

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Table 31. [1978-1991] DFHP Existing Furnace CARE
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $2,405 $273 $20,184 $12,619 $36,168
CZ02 PGE $1,670 $12 $9,216 $4,240 $13,931
CZ03 PGE $1,178 $76 $8,952 $5,930 $14,293
CZ04 PGE $1,670 $23 $8,234 $3,777 $11,336
CZ04 CPAU $1,670 $0 $8,234 $786 $786
CZ05 PGE $1,424 $40 $7,070 $4,285 $11,150
CZ05 PGE/SCG $1,424 ($122) $7,070 ($400) $3,130
CZ06 SCE/SCG $1,424 ($21) $2,941 $952 $1,705
CZ07 SDGE $1,424 $9 $3,046 $1,631 $2,667
CZ08 SCE/SCG $1,916 ($45) $2,294 ($246) $693
CZ09 SCE/SCG $1,916 ($67) $3,127 ($563) $861
CZ10 SCE/SCG $1,916 ($50) $2,755 ($208) $1,125
CZ10 SDGE $1,916 $110 $2,755 $3,621 $5,975
CZ11 PGE $2,162 $155 $9,192 $6,617 $16,577
CZ12 PGE $1,916 $128 $9,753 $6,583 $16,702
CZ12 SMUD/PGE $1,916 $506 $9,753 $15,028 $25,418
CZ13 PGE $2,162 $135 $6,312 $5,245 $12,393
CZ14 SCE/SCG $1,916 ($128) $5,080 ($1,202) $2,261
CZ14 SDGE $1,916 $65 $5,080 $3,272 $8,344
CZ15 SCE/SCG $2,408 ($9) $50 ($504) ($107)
CZ16 PGE $2,243 $28 $14,397 $4,676 $19,471

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Table 32. [1978-1991] Standard Efficiency HPSH CARE
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $3,067 $146 $21,427 $8,941 $34,641
CZ02 PGE $652 ($47) $10,428 $3,076 $14,864
CZ03 PGE $514 $33 $8,999 $4,259 $12,882
CZ04 PGE $652 ($10) $9,984 $3,558 $14,338
CZ04 CPAU $652 $0 $9,984 $255 $255
CZ05 PGE $583 ($18) $7,290 $2,586 $10,196
CZ05 PGE/SCG $583 ($199) $7,290 ($2,659) $1,219
CZ06 SCE/SCG $583 ($24) $2,450 $215 $956
CZ07 SDGE $583 $6 $2,539 $898 $1,929
CZ08 SCE/SCG $721 ($57) $2,111 ($896) $57
CZ09 SCE/SCG $721 ($91) $3,022 ($1,455) $13
CZ10 SCE/SCG $721 ($71) $2,672 ($1,035) $390
CZ10 SDGE $721 $96 $2,672 $2,939 $5,474
CZ11 PGE $790 $74 $10,682 $5,209 $16,830
CZ12 PGE $721 $30 $10,747 $4,418 $15,794
CZ12 SMUD/PGE $721 $573 $10,747 $16,567 $28,332
CZ13 PGE $790 $72 $7,141 $4,003 $12,047
CZ14 SCE/SCG $721 ($224) $7,556 ($2,880) $2,930
CZ14 SDGE $721 $42 $7,556 $3,476 $12,809
CZ15 SCE/SCG $859 ($13) $71 ($639) ($219)
CZ16 PGE $2,095 ($25) $22,236 $7,529 $37,120

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Table 33. [1978-1991] High Efficiency HPSH CARE
Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
First-year
Utility
Savings
Lifecycle NPV Savings
2025

LSC NPV
On-Bill NPV
Modest Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $5,998 $339 $23,092 $8,460 $34,300
CZ02 PGE $3,606 $57 $9,242 $547 $12,409
CZ03 PGE $3,422 $111 $6,872 $1,228 $9,907
CZ04 PGE $3,606 $113 $9,114 $1,472 $12,340
CZ04 CPAU $3,606 $0 $9,114 ($4,595) ($4,595)
CZ05 PGE $3,514 $58 $4,859 ($544) $7,120
CZ05 PGE/SCG $3,514 ($124) $4,859 ($5,789) ($1,857)
CZ06 SCE/SCG $3,514 $5 ($1,546) ($3,963) ($3,196)
CZ07 SDGE $3,514 $39 ($1,407) ($3,143) ($2,122)
CZ08 SCE/SCG $3,698 $32 ($828) ($3,800) ($2,766)
CZ09 SCE/SCG $3,698 ($0) $232 ($4,336) ($2,784)
CZ10 SCE/SCG $3,698 $25 $82 ($3,803) ($2,290)
CZ10 SDGE $3,698 $184 $82 $124 $2,631
CZ11 PGE $3,789 $272 $10,685 $4,725 $16,488
CZ12 PGE $3,698 $191 $10,023 $3,148 $14,639
CZ12 SMUD/PGE $3,698 $573 $10,023 $11,680 $23,445
CZ13 PGE $3,789 $259 $6,612 $3,262 $11,441
CZ14 SCE/SCG $3,698 ($82) $7,697 ($4,629) $1,311
CZ14 SDGE $3,698 $195 $7,697 $2,166 $11,452
CZ15 SCE/SCG $3,881 $133 ($1,111) ($2,349) ($1,794)
CZ16 PGE $5,071 $245 $26,407 $8,685 $38,470

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6.3 Utility Rate Schedules

6.3.1 Pacific Gas & Electric
The following pages provide details on the PG&E electricity and natural gas tariffs applied in this study. Table 34 describes the baseline territories that were assumed for each climate zone. A net surplus compensation rate of $ 0.03396/ kWh was applied to any net annual electricity generation based on a one-year average of the rates between February 2024 and January 2025.

Table 34. PG&E Baseline Territory by Climate Zone
Climate
Zone
Baseline
Territory
CZ01 V
CZ02 X
CZ03 T
CZ04 X
CZ05 T
CZ11 R
CZ12 S
CZ13 R
CZ16 Y

The PG&E monthly gas rate in $/therm was applied on a monthly basis according to the rates shown in Table 35. The gas rates were developed based on the latest available gas rate for January 2025 and a curve to reflect how natural gas prices fluctuate with seasonal supply and demand. The seasonal curve was estimated from PG&E’s monthly residential tariffs between 2015 and 2024. 12-month curves were created from monthly gas rates for each of the ten years. The ten annual curves were then averaged to arrive at an average normalized annual curve. The baseline and excess transmission charges were found to be consistent over the course of a year and applied for the entire year based on January 2025 rates. The costs presented in Table 35 were then derived by establishing the baseline and excess rates from the latest January 2025 tariff as a reference point, and then using the normalized curve to estimate the cost for the remaining months relative to the January rates.

Corresponding CARE tariffs reflect the 20 percent discount per the GL-1 tariff.

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Table 35. PG&E Monthly Gas Rate ($/therm)
Month
Total Charge
Baseline Excess
January $2.63 $3.15
February $2.64 $3.16
March $2.41 $2.94
April $2.24 $2.77
May $2.21 $2.74
June $2.23 $2.77
July $2.26 $2.80
August $2.36 $2.90
September $2.42 $2.98
October $2.52 $3.07
November $2.63 $3.17
December $2.70 $3.23
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Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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6.3.2 Southern California Edison
The following pages provide details on the SCE electricity tariffs applied in this study. Table describes the baseline territories that were assumed for each climate zone. A net surplus compensation rate of $ 0.01532/ kWh was applied to any net annual electricity generation based on a one-year average of the rates between February 2024 and January 2025.

Table 36. SCE Baseline Territory by Climate Zone
Climate
Zone
Baseline
Territory
CZ06 6
CZ08 8
CZ09 9
CZ10 10
CZ14 14
CZ15 15

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6.3.3 Southern California Gas
Following are the SoCalGas natural gas tariffs applied in this study. Table 37 describes the baseline territories that were assumed for each climate zone.

Table 37. SoCalGas Baseline Territory by Climate Zone
Climate
Zone
Baseline
Territory
CZ05 2
CZ06 1
CZ08 1
CZ09 1
CZ10 1
CZ14 2
CZ15 1

The SoCalGas monthly gas rate in $/therm applied in this analysis is shown in Table 38. The gas rates were developed based on the latest available gas rate for January 2025 and a curve to reflect how natural gas prices fluctuate with seasonal supply and demand. The seasonal curve was estimated from SoCalGas’s monthly residential tariffs between 2015 and 2024. 12-month curves were created from monthly gas rates for each of the ten years. The ten annual curves were then averaged to arrive at an average normalized annual curve.

Long-term historical natural gas rate data was only available for SoCalGas’ procurement charges.8 The baseline and excess transmission charges were found to be consistent over the course of a year and applied for the entire year based on January 2025 rates. The costs presented in Table 38 were then derived by establishing the baseline and excess rates from the latest January 2025 tariff as a reference point, and then using the normalized curve to estimate the cost for the remaining months relative to the January rates. CARE tariffs reflect the 20 percent discount per the GR tariff.

8 The SoCalGas procurement and transmission charges were obtained from the following site:
https://www.socalgas.com/for-your-business/energy-market-services/gas-prices RES2023.xlsx (live.com)
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Table 38. SoCalGas Monthly Gas Rate ($/therm)
Month Procurement
Charge
Transportation Charge Total Charge
Baseline Excess Baseline Excess
January $0.45 $0.98 $1.40 $1.43 $1.85
February $0.31 $0.98 $1.40 $1.29 $1.71
March $0.26 $0.98 $1.40 $1.24 $1.66
April $0.21 $0.98 $1.40 $1.19 $1.62
May $0.22 $0.98 $1.40 $1.20 $1.62
June $0.25 $0.98 $1.40 $1.23 $1.65
July $0.26 $0.98 $1.40 $1.24 $1.66
August $0.29 $0.98 $1.40 $1.27 $1.70
September $0.27 $0.98 $1.40 $1.25 $1.67
October $0.26 $0.98 $1.40 $1.24 $1.66
November $0.29 $0.98 $1.40 $1.27 $1.69
December $0.33 $0.98 $1.40 $1.31 $1.73

6.3.4 San Diego Gas & Electric
Following are the SDG&E electricity and natural gas tariffs applied in this study. Table 39 describes the baseline territories that were assumed for each climate zone. A net surplus compensation rate of $ 0.01837/ kWh was applied to any net annual electricity generation based on a one-year average of the rates between February 2024 and January 2025.

Table 39. SDG&E Baseline Territory by Climate Zone
Climate
Zone
Baseline
Territory
CZ07 Coastal
CZ10 Inland
CZ14 Mountain

The SDG&E monthly gas rate in $/therm was applied on a monthly basis according to the rates shown in Table 40. The gas rates were developed based on the latest available gas rate for January 2025 and a curve to reflect how natural gas prices fluctuate with seasonal supply and demand. The seasonal curve was estimated from SDG&E’s monthly residential tariffs between 2015 and 2024. 12-month curves were created from monthly gas rates for each of the ten years. The ten annual curves were then averaged to arrive at an average normalized annual curve. The baseline and excess transmission charges were found to be consistent over the course of a year and applied for the entire year based on January 2025 rates. The costs presented in Table 40 were then derived by establishing the baseline and excess rates from the latest January 2025 tariff as a reference point, and then using the normalized curve to estimate the cost for the remaining months relative to the January rates.

CARE tariffs reflect the 20 percent discount per the G-CARE tariff.

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Table 40. SDG&E Monthly Gas Rate ($/therm)
Month
Total Charge
Baseline Excess
January $2.07 $2.36
February $2.01 $2.30
March $1.93 $2.22
April $1.86 $2.16
May $1.88 $2.18
June $1.94 $2.24
July $1.95 $2.25
August $2.02 $2.32
September $1.97 $2.27
October $1.94 $2.24
November $1.97 $2.27
December $2.07 $2.37

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Cost-effectiveness Analysis: Single Family AC to Heat Pump Replacement

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6.3.5 City of Palo Alto Utilities
Following are the CPAU electricity and natural gas tariffs applied in this study. The CPAU monthly gas rate in $/therm was applied on a monthly basis according to the rates shown in Table 41. The gas rates were developed based on the latest available gas rate for January 2025 and a curve to reflect how natural gas prices fluctuate with seasonal supply and demand. The seasonal curve was estimated from CPAU’s monthly residential tariffs between 2018 and 2024. 12-month curves were created from monthly gas rates for each of the seven years. The seven annual curves were then averaged to arrive at an average normalized annual curve. The baseline and excess transmission charges were found to be consistent over the course of a year and applied for the entire year based on January 2025 rates. The costs presented in Table 41 were then derived by establishing the baseline and excess rates from the latest January 2025 tariff as a reference point and then using the normalized curve to estimate the cost for the remaining months relative to the January rates. The monthly service charge applied was $16.93 per month per the January 2025 G-1 tariff.

Table 41. CPAU Monthly Gas Rate ($/therm)
Month G1 Volumetric
Total Baseline
G1 Volumetric
Total Excess
January $1.74 $3.02
February $1.33 $2.53
March $1.24 $2.43
April $1.21 $2.39
May $1.21 $2.39
June $1.23 $2.42
July $1.31 $2.64
August $1.37 $2.71
September $1.36 $2.71
October $1.38 $2.72
November $1.45 $2.80
December $1.57 $2.96

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6.3.6 Sacramento Municipal Utilities District (Electric Only) Following are the SMUD electricity tariffs applied in this study. The rates effective January 2025 were used.

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6.3.7 Fuel Escalation Assumptions
The average annual escalation rates in Table 42 and Table 43 were used in this study. Table 42 rates are based on assumptions from the CPUC 2021 En Banc hearings on utility costs through 2030 (California Public Utilities Commission, 2021a). Escalation rates through the remainder of the 30-year evaluation period are based on the escalation rate assumptions within the 2022 TDV factors. No data was available to estimate electricity escalation rates for CPAU and SMUD, therefore electricity escalation rates for PG&E and statewide natural gas escalation rates were applied. Table 43 rates are based on the escalation rate assumptions within the 2025 LSC factors from 2026 through 2055.
9 These rates were developed for
electricity use statewide (not utility-specific) and assume steep increases in gas rates in the latter half of the analysis period. Data was not available for the year 2026 and so the CPUC En Banc assumptions were applied for those years using the average rate across the three IOUs for statewide electricity escalation.

9https://www.energy.ca.gov/files/2025-energy-code-hourly-factors. (California Energy Commission, 2023). Actual escalation factors were provided by consultants E3.

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Table 42. Real Utility Rate Escalation Rate Assumptions, CPUC En Banc and 2022 TDV Basis

Statewide Natural
Gas Residential
Average Rate
(%/year, real)
Electric Residential Average Rate
(%/year, real)

PG&E SCE SDG&E
2026 4.6% 1.8% 1.6% 2.8%
2027 4.6% 1.8% 1.6% 2.8%
2028 4.6% 1.8% 1.6% 2.8%
2029 4.6% 1.8% 1.6% 2.8%
2030 4.6% 1.8% 1.6% 2.8%
2031 2.0% 0.6% 0.6% 0.6%
2032 2.4% 0.6% 0.6% 0.6%
2033 2.1% 0.6% 0.6% 0.6%
2034 1.9% 0.6% 0.6% 0.6%
2035 1.9% 0.6% 0.6% 0.6%
2036 1.8% 0.6% 0.6% 0.6%
2037 1.7% 0.6% 0.6% 0.6%
2038 1.6% 0.6% 0.6% 0.6%
2039 2.1% 0.6% 0.6% 0.6%
2040 1.6% 0.6% 0.6% 0.6%
2041 2.2% 0.6% 0.6% 0.6%
2042 2.2% 0.6% 0.6% 0.6%
2043 2.3% 0.6% 0.6% 0.6%
2044 2.4% 0.6% 0.6% 0.6%
2045 2.5% 0.6% 0.6% 0.6%
2046 1.5% 0.6% 0.6% 0.6%
2047 1.3% 0.6% 0.6% 0.6%
2048 1.6% 0.6% 0.6% 0.6%
2049 1.3% 0.6% 0.6% 0.6%
2050 1.5% 0.6% 0.6% 0.6%
2051 1.8% 0.6% 0.6% 0.6%
2052 1.8% 0.6% 0.6% 0.6%
2053 1.8% 0.6% 0.6% 0.6%
2054 1.8% 0.6% 0.6% 0.6%
2055 1.8% 0.6% 0.6% 0.6%
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Table 43. Real Utility Rate Escalation Rate Assumptions, 2025 LSC Basis

Year
Statewide Natural
Gas Residential
Average Rate
(%/year, real)
Statewide
Electricity
Residential
Average Rate
(%/year, real)
2026 4.6% 2.1%
2027 4.2% 0.6%
2028 3.2% 1.9%
2029 3.6% 1.6%
2030 6.6% 1.3%
2031 6.7% 1.0%
2032 7.7% 1.2%
2033 8.2% 1.1%
2034 8.2% 1.1%
2035 8.2% 0.9%
2036 8.2% 1.1%
2037 8.2% 1.1%
2038 8.2% 1.0%
2039 8.2% 1.1%
2040 8.2% 1.1%
2041 8.2% 1.1%
2042 8.2% 1.1%
2043 8.2% 1.1%
2044 8.2% 1.1%
2045 8.2% 1.1%
2046 8.2% 1.1%
2047 3.1% 1.1%
2048 -0.5% 1.1%
2049 -0.6% 1.1%
2050 -0.5% 1.1%
2051 -0.6% 1.1%
2052 -0.6% 1.1%
2053 -0.6% 1.1%
2054 -0.6% 1.1%
2055 -0.6% 1.1%
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Last modified: 2025/06/09