Application of the 2022
Studies to the 2025
Energy Code:
Existing Single Family
Building Upgrades
Prepared by:
Frontier Energy, Inc
Misti Bruceri & Associates, LLC
Prepared for:
Kelly Cunningham, Codes and
Standards Program, Pacific Gas
and Electric
Revision: 1.0
Last modified: 2025/08/15
2025 Energy Code: Existing Single Family Building Upgrades
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Table 1 Summary of Revisions
Date Description Reference (page or section)
8/15/2025 Original Release N/A
Legal Notice
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2025 Energy Code: Existing Single Family Building Upgrades
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Acronym List
B/C – Lifecycle Benefit-to-Cost
Ratio
CASE – Codes and Standards
Enhancement
CFL – Compact Fluorescent
Lamps
CPAU – City of Palo Alto Utilities
CPUC – California Public Utilities
Commission
CZ – California Climate Zone
kWh – Kilowatt Hour
NPV – Net Present Value
PG&E – Pacific Gas and Electric
Company
PV – Photovoltaic
SCE – Southern California
Edison
SDG&E – San Diego Gas and
Electric
SMUD – Sacramento Municipal
Utility District
SoCalGas – Southern California
Gas Company
Therm – Unit for quantity of heat
that equals 100,000 British
thermal units
2025 Energy Code: Existing Single Family Building Upgrades
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Table of Contents
1 Summary ...................................................................................................................... 2 2 Air Sealing at the Ceiling ............................................................................................. 4 3 Lighting Measures ..................................................................................................... 10 4 Water Heating Package .............................................................................................. 14 5 PV ................................................................................................................................ 15 6 References ................................................................................................................. 22
List of Tables
Table 1 Summary of Revisions ............................................................................................. 1 Table 2. [Pre-1978] Air Sealing at the Ceiling (Std) ............................................................... 4 Table 3. [1978-1991] Air Sealing at the Ceiling (Std) ............................................................ 5 Table 4. [1992-2010] Air Sealing at the Ceiling (Std) ............................................................ 6 Table 5. [Pre-1978] Air Sealing at the Ceiling (CARE) .......................................................... 7 Table 6. [1978-1991] Air Sealing at the Ceiling (CARE) ........................................................ 8 Table 7. [1991-2010] Air Sealing at the Ceiling (CARE) ........................................................ 9 Table 8. [All Vintages] LED Lamp vs. CFL ........................................................................... 11 Table 9. [All Vintages] Exterior Photosensor ........................................................................12 Table 10. [All Vintages] LED and Photosensor ....................................................................13 Table 11. [All Vintages] Water Heating Package ..................................................................14 Table 12. [Pre-1978] 3 kW PV without Solar Tax Credit (Std) ..............................................16 Table 13. [1978-1991] 3 kW PV without Solar Tax Credit (Std) ...........................................17 Table 14. [1992-2010] 3 kW PV without Solar Tax Credit (Std) ............................................18 Table 15. [Pre-1978] 3 kW PV without Solar Tax Credit (CARE) ..........................................19 Table 16. [1978-1991] 3 kW PV without Solar Tax Credit (CARE) .......................................20 Table 17. [1992-2010] 3 kW PV without Solar Tax Credit (CARE) .......................................21 List of Figures
No table of figures entries found.
2025 Energy Code: Existing Single Family Building Upgrades
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1 Summary
The California Codes and Standards (C&S) Reach 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 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.
In April 2024, the Statewide Reach Codes Team published the 2022 Cost-Effectiveness Study: Existing Single Family Building Upgrades. This study focuses on existing single family buildings identifying cost-effective measures and measure package upgrades in all 16 California climate zones. The study was conducted to complement Part 6 of the California Building Code (the Energy Code) for the 2022 code cycle, effective January 1, 2023. In the 2019 code cycle the 2019 Cost-Effectiveness Study: Existing Single Family Residential Building Upgrades study included outdoor lighting and a water heater package that was discontinued in the 2022 study but has been brought back in this memo by request from jurisdictions. The studies document the estimated costs, benefits, energy impacts and greenhouse gas emission reductions that may result from implementing an ordinance to help local leadership, residents, and other stakeholders make informed policy decisions.
The Statewide Reach Codes Team reviewed the cost-effectiveness study for impacts of code changes implemented in the 2025 Energy Code. Measures that are now required by code may alter the results presented in the 2022 study. Below is a summary of the changes to the additions and alterations for residential buildings sections of the 2025 Energy Code. • Mandatory wall insulation R-value has been increased from R-13 to R-15. [Section 150.2(a) of the Energy Code]
• Prescriptive window U-factor has decreased from 0.30 to 0.27 in Climate Zones 1-5, 11-14, and 16. [Section 150.2(b)1B of the Energy Code]
The wall insulation measure has been re-evaluated with R-15 instead of R-13. There is generally a slight increase in utility cost savings as expected with the increase in efficiency.
However, there is not a substantial impact on the cost-effectiveness results.
For the prescriptive window U-factor, the original study modeled U-0.28 in all climate zones.
This updated memo drops the U-factor from 0.28 to 0.27 in all climate zones. The SHGC is maintained at 0.23 for climate zone 2, 4, and 6-15 and 0.35 for CZ 1, 3, 5, 16. There is minimal impact on the cost-effectiveness results due to this update. However, there are two instances in the 1978-1991 vintage where cost-effectiveness flips from cost-effective to not cost-effective. Climate zone 4 in PGE territory utilizing standard rates and the modest gas escalation is no longer cost-effective on-bill by the smallest margin. Climate zone 10 in SDGE territory utilizing CARE rates and the modest gas escalation has also become no longer cost-effective on-bill.
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The 2022 study included a whole building air sealing measure defined as a 30% reduction in air leakage. A new measure – air sealing of the ceiling floor, representing a 14% reduction in air leakage – is added in this memo. Further details and cost-effectiveness results are provided in Section 2.
Lighting measures were previously presented in the 2019 Cost-Effectiveness Study: Existing Single Family Residential Building Upgrades study but were not analyzed in the 2022 study.
Updated cost-effectiveness analysis for this measure is presented in Section 3.
The water heating package measure was previously presented in 2019 Cost-Effectiveness Study: Existing Single Family Residential Building Upgrades study. Updated cost- effectiveness analysis for this measure is presented in Section 4.
The 3 kW PV measure from the 2022 study is revised here with an updated cost- effectiveness analysis that accounts for the elimination of the Federal Solar tax credit December 31, 2025. Additional details and analysis are provided in Section 5.
The 2022 report, 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 Air Sealing at the Ceiling
Unlike full air sealing, which has previously been presented, air sealing of the ceiling floor may be an attractive measure for an attic remodel project. The whole building air sealing measure estimated a 30% reduction in air leakage, while air sealing at the ceiling measure results in a 14% reduction in air leakage.
Table 2 through Table 7 present the cost-effectiveness results for the air sealing at the ceiling plane measure. The estimated incremental cost for air sealing at the ceiling plane is $1,963 which is from the 2022 Residential Additions and Alterations CASE Report (Statewide CASE Team, 2020).
Table 2. [Pre-1978] Air Sealing at the Ceiling (Std)
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 $1,963 $33 ($465) ($997) ($432)
CZ02 PGE $1,963 $18 ($1,114) ($1,433) ($1,118)
CZ03 PGE $1,963 $17 ($1,180) ($1,463) ($1,171)
CZ04 PGE $1,963 $25 ($1,081) ($1,290) ($979)
CZ04 CPAU $1,963 $21 ($1,081) ($1,379) ($1,069)
CZ05 PGE $1,963 $16 ($1,230) ($1,500) ($1,235)
CZ05 PGE/SCG $1,963 $14 ($1,230) ($1,555) ($1,325)
CZ06 SCE/SCG $1,963 ($2) ($1,797) ($1,987) ($1,937)
CZ07 SDGE $1,963 ($3) ($1,813) ($2,008) ($1,934)
CZ08 SCE/SCG $1,963 $7 ($1,680) ($1,775) ($1,703)
CZ09 SCE/SCG $1,963 $10 ($1,597) ($1,693) ($1,592)
CZ10 SCE/SCG $1,963 $17 ($1,497) ($1,540) ($1,420)
CZ10 SDGE $1,963 $23 ($1,497) ($1,366) ($1,237)
CZ11 PGE $1,963 $32 ($1,014) ($1,120) ($816)
CZ12 PGE $1,963 $22 ($1,147) ($1,348) ($1,064)
CZ12 SMUD/PGE $1,963 $17 ($1,147) ($1,468) ($1,190)
CZ13 PGE $1,963 $31 ($1,114) ($1,162) ($918)
CZ14 SCE/SCG $1,963 $32 ($897) ($1,130) ($832)
CZ14 SDGE $1,963 $42 ($897) ($845) ($519)
CZ15 SCE/SCG $1,963 $40 ($1,297) ($1,041) ($946)
CZ16 PGE $1,963 $30 ($581) ($1,071) ($551)
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Table 3. [1978-1991] Air Sealing at the Ceiling (Std)
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 $1,963 $23 ($931) ($1,292) ($903)
CZ02 PGE $1,963 $13 ($1,364) ($1,570) ($1,341)
CZ03 PGE $1,963 $10 ($1,480) ($1,668) ($1,496)
CZ04 PGE $1,963 $16 ($1,330) ($1,522) ($1,292)
CZ04 CPAU $1,963 $13 ($1,330) ($1,575) ($1,356)
CZ05 PGE $1,963 $11 ($1,447) ($1,649) ($1,466)
CZ05 PGE/SCG $1,963 $10 ($1,447) ($1,684) ($1,522)
CZ06 SCE/SCG $1,963 ($1) ($1,830) ($1,967) ($1,934)
CZ07 SDGE $1,963 ($4) ($1,896) ($2,040) ($1,991)
CZ08 SCE/SCG $1,963 $4 ($1,797) ($1,860) ($1,813)
CZ09 SCE/SCG $1,963 $5 ($1,747) ($1,823) ($1,764)
CZ10 SCE/SCG $1,963 $10 ($1,663) ($1,722) ($1,652)
CZ10 SDGE $1,963 $14 ($1,663) ($1,603) ($1,517)
CZ11 PGE $1,963 $25 ($1,264) ($1,320) ($1,096)
CZ12 PGE $1,963 $16 ($1,380) ($1,520) ($1,314)
CZ12 SMUD/PGE $1,963 $12 ($1,380) ($1,604) ($1,402)
CZ13 PGE $1,963 $23 ($1,364) ($1,373) ($1,199)
CZ14 SCE/SCG $1,963 $22 ($1,230) ($1,397) ($1,182)
CZ14 SDGE $1,963 $28 ($1,230) ($1,212) ($974)
CZ15 SCE/SCG $1,963 $32 ($1,463) ($1,225) ($1,154)
CZ16 PGE $1,963 $21 ($1,014) ($1,357) ($1,001)
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Table 4. [1992-2010] Air Sealing at the Ceiling (Std)
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 $1,963 $14 ($1,314) ($1,550) ($1,309)
CZ02 PGE $1,963 $9 ($1,530) ($1,687) ($1,529)
CZ03 PGE $1,963 $7 ($1,613) ($1,744) ($1,618)
CZ04 PGE $1,963 $11 ($1,530) ($1,653) ($1,501)
CZ04 CPAU $1,963 $9 ($1,530) ($1,701) ($1,557)
CZ05 PGE $1,963 $7 ($1,613) ($1,759) ($1,637)
CZ05 PGE/SCG $1,963 $6 ($1,613) ($1,788) ($1,686)
CZ06 SCE/SCG $1,963 $1 ($1,863) ($1,936) ($1,911)
CZ07 SDGE $1,963 $0 ($1,896) ($1,944) ($1,911)
CZ08 SCE/SCG $1,963 $3 ($1,830) ($1,885) ($1,851)
CZ09 SCE/SCG $1,963 $3 ($1,780) ($1,892) ($1,853)
CZ10 SCE/SCG $1,963 $6 ($1,763) ($1,814) ($1,767)
CZ10 SDGE $1,963 $8 ($1,763) ($1,741) ($1,681)
CZ11 PGE $1,963 $14 ($1,530) ($1,581) ($1,437)
CZ12 PGE $1,963 $10 ($1,580) ($1,693) ($1,560)
CZ12 SMUD/PGE $1,963 $8 ($1,580) ($1,737) ($1,606)
CZ13 PGE $1,963 $12 ($1,580) ($1,643) ($1,531)
CZ14 SCE/SCG $1,963 $12 ($1,530) ($1,639) ($1,503)
CZ14 SDGE $1,963 $16 ($1,530) ($1,537) ($1,382)
CZ15 SCE/SCG $1,963 $17 ($1,680) ($1,572) ($1,532)
CZ16 PGE $1,963 $14 ($1,314) ($1,556) ($1,314)
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Table 5. [Pre-1978] Air Sealing at the Ceiling (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 $1,963 $26 ($465) ($1,212) ($766)
CZ02 PGE $1,963 $14 ($1,114) ($1,550) ($1,302)
CZ03 PGE $1,963 $13 ($1,180) ($1,574) ($1,343)
CZ04 PGE $1,963 $18 ($1,081) ($1,459) ($1,216)
CZ04 CPAU $1,963 $0 ($1,081) ($1,963) ($1,963)
CZ05 PGE $1,963 $12 ($1,230) ($1,604) ($1,395)
CZ05 PGE/SCG $1,963 $11 ($1,230) ($1,648) ($1,467)
CZ06 SCE/SCG $1,963 ($1) ($1,797) ($1,969) ($1,928)
CZ07 SDGE $1,963 ($1) ($1,813) ($1,976) ($1,918)
CZ08 SCE/SCG $1,963 $5 ($1,680) ($1,824) ($1,768)
CZ09 SCE/SCG $1,963 $8 ($1,597) ($1,764) ($1,686)
CZ10 SCE/SCG $1,963 $12 ($1,497) ($1,659) ($1,566)
CZ10 SDGE $1,963 $16 ($1,497) ($1,546) ($1,443)
CZ11 PGE $1,963 $23 ($1,014) ($1,353) ($1,116)
CZ12 PGE $1,963 $17 ($1,147) ($1,503) ($1,279)
CZ12 SMUD/PGE $1,963 $11 ($1,147) ($1,623) ($1,406)
CZ13 PGE $1,963 $22 ($1,114) ($1,394) ($1,205)
CZ14 SCE/SCG $1,963 $23 ($897) ($1,352) ($1,120)
CZ14 SDGE $1,963 $30 ($897) ($1,163) ($905)
CZ15 SCE/SCG $1,963 $27 ($1,297) ($1,334) ($1,266)
CZ16 PGE $1,963 $24 ($581) ($1,270) ($859)
2025 Energy Code: Existing Single Family Building Upgrades
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Table 6. [1978-1991] Air Sealing at the Ceiling (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 $1,963 $18 ($931) ($1,442) ($1,135)
CZ02 PGE $1,963 $10 ($1,364) ($1,658) ($1,477)
CZ03 PGE $1,963 $8 ($1,480) ($1,734) ($1,598)
CZ04 PGE $1,963 $12 ($1,330) ($1,627) ($1,446)
CZ04 CPAU $1,963 $0 ($1,330) ($1,963) ($1,963)
CZ05 PGE $1,963 $8 ($1,447) ($1,719) ($1,575)
CZ05 PGE/SCG $1,963 $7 ($1,447) ($1,746) ($1,619)
CZ06 SCE/SCG $1,963 ($0) ($1,830) ($1,959) ($1,933)
CZ07 SDGE $1,963 ($2) ($1,896) ($2,003) ($1,964)
CZ08 SCE/SCG $1,963 $3 ($1,797) ($1,886) ($1,848)
CZ09 SCE/SCG $1,963 $4 ($1,747) ($1,859) ($1,813)
CZ10 SCE/SCG $1,963 $7 ($1,663) ($1,790) ($1,736)
CZ10 SDGE $1,963 $10 ($1,663) ($1,710) ($1,641)
CZ11 PGE $1,963 $18 ($1,264) ($1,500) ($1,325)
CZ12 PGE $1,963 $12 ($1,380) ($1,631) ($1,469)
CZ12 SMUD/PGE $1,963 $8 ($1,380) ($1,716) ($1,558)
CZ13 PGE $1,963 $16 ($1,364) ($1,545) ($1,411)
CZ14 SCE/SCG $1,963 $16 ($1,230) ($1,545) ($1,378)
CZ14 SDGE $1,963 $20 ($1,230) ($1,422) ($1,233)
CZ15 SCE/SCG $1,963 $22 ($1,463) ($1,460) ($1,410)
CZ16 PGE $1,963 $16 ($1,014) ($1,491) ($1,211)
2025 Energy Code: Existing Single Family Building Upgrades
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Table 7. [1991-2010] Air Sealing at the Ceiling (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 $1,963 $11 ($1,314) ($1,642) ($1,452)
CZ02 PGE $1,963 $7 ($1,530) ($1,749) ($1,625)
CZ03 PGE $1,963 $6 ($1,613) ($1,793) ($1,693)
CZ04 PGE $1,963 $8 ($1,530) ($1,729) ($1,609)
CZ04 CPAU $1,963 $0 ($1,530) ($1,963) ($1,963)
CZ05 PGE $1,963 $5 ($1,613) ($1,804) ($1,708)
CZ05 PGE/SCG $1,963 $5 ($1,613) ($1,827) ($1,747)
CZ06 SCE/SCG $1,963 $1 ($1,863) ($1,940) ($1,920)
CZ07 SDGE $1,963 $0 ($1,896) ($1,944) ($1,918)
CZ08 SCE/SCG $1,963 $2 ($1,830) ($1,905) ($1,879)
CZ09 SCE/SCG $1,963 $2 ($1,780) ($1,908) ($1,878)
CZ10 SCE/SCG $1,963 $4 ($1,763) ($1,855) ($1,819)
CZ10 SDGE $1,963 $6 ($1,763) ($1,805) ($1,758)
CZ11 PGE $1,963 $10 ($1,530) ($1,685) ($1,572)
CZ12 PGE $1,963 $7 ($1,580) ($1,759) ($1,654)
CZ12 SMUD/PGE $1,963 $5 ($1,580) ($1,802) ($1,700)
CZ13 PGE $1,963 $9 ($1,580) ($1,732) ($1,644)
CZ14 SCE/SCG $1,963 $9 ($1,530) ($1,722) ($1,615)
CZ14 SDGE $1,963 $11 ($1,530) ($1,652) ($1,529)
CZ15 SCE/SCG $1,963 $12 ($1,680) ($1,696) ($1,667)
CZ16 PGE $1,963 $11 ($1,314) ($1,645) ($1,454)
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3 Lighting Measures
LED lighting and exterior lighting control measures were previously evaluated in the 2019 Cost-Effectiveness Study: Existing Single Family Residential Building Upgrades study.
These measures are not included in the 2022 Cost-Effectiveness Study: Existing Single Family Building Upgrades study, but have been re-evaluated and included in this memo.
The updated analysis follows the same methodology as the 2019 study, but with updated costs for equipment and updated utility rates.
The three measures evaluated are LED lighting, exterior photosensor, and LED lighting plus photosensor. Table 8 through Table 10 show the results for the different lighting measures evaluated. Each measure is explained in more detail below.
LED Lighting: Replace screw-in (A-based for lamps) incandescent lamps and compact fluorescent lamps (CFLs) with light-emitting diode (LED) A-lamps. This analysis was conducted external to the energy model and evaluated replacement of a 13 W CFL lamp with an 9.6 W LED lamp operating 620 hours annually. Annual hour estimates were based on whole building average hours of operation from a 2010 lighting study by KEMA (KEMA, 2010). Lifetime assumptions were 10,000 hours for CFLs and 25,000 hours for LED lamps.
For incremental cost calculations it was assumed CFLs have a lifetime of 15 years, are installed five years prior to the retrofit, and would need to be replaced at year ten and 25.
Exterior Lighting Controls/Photosensor: Evaluation of exterior lighting controls was completed on a per-luminaire basis external to the energy model and assumes a screw-in photosensor control is installed in outdoor lighting luminaires. Energy savings of 12.1 kWh per year was applied based on analysis done by the Consortium for Energy Efficiency, assuming LED lamps, 2.6 hours per day of operation, and that photosensor controls reduce operating hours on average 20 percent each day (CEE, 2014). Energy savings will be higher for incandescent or CFL luminaires.
Exterior Lighting Controls/Photosensor+LED: An additional evaluation was completed for exterior lighting controls on a per-luminaire basis external to the energy model and assumes a screw-in photosensor control is installed in outdoor lighting luminaires and incandescent lamps CFLs are replaced with light-emitting diode (LED) A-lamps. Energy savings of 14.3 kWh per year was applied based on the sum of the LED lighting and Exterior Lighting Controls with Photosensor kWh energy savings.
For the measures including a LED, a cost of $3.49 for LED dimmable A19 lamp 60 W equivalent is used. A cost of $1.74 is used for an equivalent CFL product which was used to estimate total replacement costs at years 10 and 25. Costs are based on a single LED lamp replacement. For the photosensor, an incremental cost of $12.62, based on a screw-in photosensor control, was obtained from an on-line product search of available products. A five-year lifetime for this type of control was assumed. 2025 Energy Code: Existing Single Family Building Upgrades
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Table 8. [All Vintages] LED Lamp vs. CFL
Climate
Zone
Electric/ Gas
Utility
Measure
Cost
Electricity
Savings
First Year
Utility
Cost
Savings
Customer On-Bill
Modest Gas Escalation
Customer On-Bill
High Gas Escalation
B/C Ratio NPV B/C Ratio NPV
CZ01 PGE $1.75 2.2 $0.77 10.05 $15.82 10.58 $16.74 CZ02 PGE $1.75 2.2 $0.86 11.26 $17.94 11.85 $18.98 CZ03 PGE $1.75 2.2 $0.78 10.14 $15.99 10.68 $16.92 CZ04 PGE $1.75 2.2 $0.80 10.39 $16.42 10.94 $17.38 CZ04 CPAU $1.75 2.2 $0.41 5.32 $7.56 5.60 $8.05
CZ05 PGE $1.75 2.2 $0.78 10.14 $15.99 10.67 $16.92 CZ05 PGE/SCG $1.75 2.2 $0.78 10.14 $15.99 10.67 $16.92 CZ06 SCE/SCG $1.75 2.2 $0.66 8.44 $13.01 8.99 $13.97 CZ07 SDGE $1.75 2.2 $0.95 13.15 $21.24 13.03 $21.04 CZ08 SCE/SCG $1.75 2.2 $0.74 9.51 $14.89 10.14 $15.98 CZ09 SCE/SCG $1.75 2.2 $0.71 9.17 $14.29 9.77 $15.33 CZ10 SCE/SCG $1.75 2.2 $0.73 9.38 $14.65 9.99 $15.72 CZ10 SDGE $1.75 2.2 $1.07 14.86 $24.24 14.74 $24.02 CZ11 PGE $1.75 2.2 $0.85 11.05 $17.57 11.63 $18.59 CZ12 PGE $1.75 2.2 $0.79 10.32 $16.29 10.86 $17.24 CZ12 SMUD/PGE $1.75 2.2 $0.47 6.08 $8.88 6.40 $9.44 CZ13 PGE $1.75 2.2 $0.86 11.27 $17.96 11.86 $19.00 CZ14 SCE/SCG $1.75 2.2 $0.74 9.58 $15.00 10.21 $16.10 CZ14 SDGE $1.75 2.2 $1.06 14.68 $23.93 14.56 $23.71 CZ15 SCE/SCG $1.75 2.2 $0.78 10.01 $15.75 10.66 $16.90 CZ16 PGE $1.75 2.2 $0.77 9.98 $15.71 10.51 $16.62
2025 Energy Code: Existing Single Family Building Upgrades
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Table 9. [All Vintages] Exterior Photosensor
Climate
Zone
Electric/ Gas
Utility
Measure
Cost
Electricity
Savings
First Year
Utility
Cost
Savings
Customer On-Bill
Modest Gas Escalation
Customer On-Bill
High Gas Escalation
B/C Ratio NPV B/C
Ratio NPV
CZ01 PGE $54.03 12.1 $4.16 1.75 $40.75 1.85 $45.74 CZ02 PGE $54.03 12.1 $4.16 1.75 $40.75 1.85 $45.74 CZ03 PGE $54.03 12.1 $4.16 1.75 $40.75 1.85 $45.74 CZ04 PGE $54.03 12.1 $4.16 1.75 $40.75 1.85 $45.74 CZ04 CPAU $54.03 12.1 $2.12 0.89 ($5.69) 0.94 ($3.15) CZ05 PGE $54.03 12.1 $4.16 1.75 $40.75 1.85 $45.74 CZ05 PGE/SCG $54.03 12.1 $4.16 1.75 $40.75 1.85 $45.74 CZ06 SCE/SCG $54.03 12.1 $3.48 1.45 $24.36 1.55 $29.48 CZ07 SDGE $54.03 12.1 $5.07 2.27 $68.58 2.25 $67.53 CZ08 SCE/SCG $54.03 12.1 $3.48 1.45 $24.36 1.55 $29.48 CZ09 SCE/SCG $54.03 12.1 $3.48 1.45 $24.36 1.55 $29.48 CZ10 SCE/SCG $54.03 12.1 $3.48 1.45 $24.36 1.55 $29.48 CZ10 SDGE $54.03 12.1 $5.07 2.27 $68.58 2.25 $67.53 CZ11 PGE $54.03 12.1 $4.16 1.75 $40.75 1.85 $45.74 CZ12 PGE $54.03 12.1 $4.16 1.75 $40.75 1.85 $45.74 CZ12 SMUD/PGE $54.03 12.1 $1.46 0.62 ($20.73) 0.65 ($18.98) CZ13 PGE $54.03 12.1 $4.16 1.75 $40.75 1.85 $45.74 CZ14 SCE/SCG $54.03 12.1 $3.48 1.45 $24.36 1.55 $29.48 CZ14 SDGE $54.03 12.1 $5.07 2.27 $68.58 2.25 $67.53 CZ15 SCE/SCG $54.03 12.1 $3.48 1.45 $24.36 1.55 $29.48 CZ16 PGE $54.03 12.1 $4.16 1.75 $40.75 1.85 $45.74
2025 Energy Code: Existing Single Family Building Upgrades
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Table 10. [All Vintages] LED and Photosensor
Climate
Zone
Electric/ Gas
Utility
Measure
Cost
Electricity
Savings
First Year
Utility Cost
Savings
Customer On-Bill
Modest Gas Escalation
Customer On-Bill High
Gas Escalation
B/C Ratio NPV B/C Ratio NPV
CZ01 PGE $55.77 14.3 $4.93 2.01 $56.57 2.12 $62.48 CZ02 PGE $55.77 14.3 $5.02 2.05 $58.70 2.16 $64.72 CZ03 PGE $55.77 14.3 $4.94 2.02 $56.74 2.12 $62.66 CZ04 PGE $55.77 14.3 $4.95 2.03 $57.17 2.13 $63.12 CZ04 CPAU $55.77 14.3 $2.53 1.03 $1.87 1.09 $4.90 CZ05 PGE $55.77 14.3 $4.94 2.02 $56.74 2.12 $62.66 CZ05 PGE/SCG $55.77 14.3 $4.94 2.02 $56.74 2.12 $62.66 CZ06 SCE/SCG $55.77 14.3 $4.13 1.67 $37.37 1.78 $43.45 CZ07 SDGE $55.77 14.3 $6.02 2.61 $89.82 2.59 $88.57 CZ08 SCE/SCG $55.77 14.3 $4.22 1.70 $39.25 1.82 $45.46 CZ09 SCE/SCG $55.77 14.3 $4.19 1.69 $38.65 1.80 $44.82 CZ10 SCE/SCG $55.77 14.3 $4.21 1.70 $39.01 1.81 $45.20 CZ10 SDGE $55.77 14.3 $6.14 2.66 $92.82 2.64 $91.55 CZ11 PGE $55.77 14.3 $5.00 2.05 $58.33 2.15 $64.33 CZ12 PGE $55.77 14.3 $4.95 2.02 $57.05 2.13 $62.98 CZ12 SMUD/PGE $55.77 14.3 $1.93 0.79 ($11.85) 0.83 ($9.54) CZ13 PGE $55.77 14.3 $5.02 2.05 $58.71 2.16 $64.73 CZ14 SCE/SCG $55.77 14.3 $4.22 1.71 $39.37 1.82 $45.58 CZ14 SDGE $55.77 14.3 $6.13 2.66 $92.51 2.64 $91.24 CZ15 SCE/SCG $55.77 14.3 $4.26 1.72 $40.12 1.83 $46.38 CZ16 PGE $55.77 14.3 $4.92 2.01 $56.46 2.12 $62.36
2025 Energy Code: Existing Single Family Building Upgrades
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4 Water Heating Package
This package includes the following:
• R-6 water heater blanket
• R-3 hot water pipe insulation
• Low flow fixtures: two low flow showerheads and three sink aerators.
This analysis assumes the homeowner installs these measures themselves and therefore no labor costs. Costs are based on Home Depot prices from August of 2025. The water heater package is evaluated over a 15-year analysis period and assumes the modest gas escalation rate.
Table 11. [All Vintages] Water Heating Package
Climate
Zone
Electric/ Gas
Utility
Measure
Cost
Gas
Savings
(therms)
Customer On-Bill
First Year Utility
Cost Savings B/C Ratio NPV
CZ01 PGE $125.68 14.69 $31.11 3.96 $371.76
CZ02 PGE $125.68 15.60 $35.20 4.48 $437.15
CZ03 PGE $125.68 15.70 $31.43 4.00 $376.88
CZ04 PGE $125.68 16.05 $32.62 4.15 $395.78
CZ04 CPAU $125.68 16.05 $31.99 4.07 $385.77
CZ05 PGE $125.68 15.83 $31.37 3.99 $375.88
CZ05 PGE/SCG $125.68 15.83 $28.29 3.60 $326.59
CZ06 SCE/SCG $125.68 16.67 $29.18 3.71 $340.84
CZ07 SDGE $125.68 16.75 $37.25 4.74 $469.81
CZ08 SCE/SCG $125.68 16.78 $29.36 3.74 $343.80
CZ09 SCE/SCG $125.68 16.66 $29.27 3.72 $342.34
CZ10 SCE/SCG $125.68 16.58 $28.99 3.69 $337.73
CZ10 SDGE $125.68 16.58 $37.77 4.80 $478.19
CZ11 PGE $125.68 15.87 $32.96 4.19 $401.32
CZ12 PGE $125.68 15.90 $32.85 4.18 $399.47
CZ12 SMUD/PGE $125.68 15.90 $32.85 4.18 $399.47
CZ13 PGE $125.68 16.32 $33.00 4.20 $401.93
CZ14 SCE/SCG $125.68 16.11 $29.79 3.79 $350.57
CZ14 SDGE $125.68 16.11 $39.23 4.99 $501.49
CZ15 SCE/SCG $125.68 17.40 $30.16 3.84 $356.50
CZ16 PGE $125.68 15.14 $31.75 4.04 $381.87
2025 Energy Code: Existing Single Family Building Upgrades
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5 PV
The results for 3 kW PV have been updated from the 2022 study to remove the federal solar tax credit from the cost-effectiveness calculations. The removal of the solar tax credit has a substantial impact on many climate zones across all vintages and will impact the FlexPath.
The following describes the impacts and changes to cost-effectiveness from the 2022 study.
These observations are utilizing standard rates. Previously, with the solar tax credit, the 3 kW PV measure in the pre-1978 vintage was on-bill cost effective in all climate zones using both the modest and high gas escalation rates. However, with the credit removed, Climate Zones 1-3, 5, 6, and 12 are no longer cost effective on-bill for both the modest and high gas escalations.
Previously for the 1978-1991 vintage the only cases that were not on-bill cost effective were climate zones 2 and 6 utilizing the modest gas escalation. Now, with the credit removed, many more climate zones are no longer cost effective. Using the modest gas escalation, climate zones 1-3, 5, 6, 12, and 16 are not cost effective on-bill. Using the high gas escalation, climate zones 1-3, 5, 6, and 12 (SMUD) are not cost effective on-bill.
Previously for the 1992-2010 vintage the following cases were not cost effective on-bill:
climate zones 1-3, 5, and 6 utilizing the modest gas escalation and climate zone 6 using the high gas escalation. With the credit removed an increased number of climate zones are no longer cost effective. Using the modest gas escalation, climate zones 1-3, 4 (PGE) 5-9, 10 (SCE/SCG),12, and 16 are not cost effective on-bill. Using the high gas escalation, climate zones 1-3, 4 (PGE), 5-7, 9, 12, and 16 are not cost effective on-bill.
The cost-effectiveness results are presented in Table 12 through Table 1717.
2025 Energy Code: Existing Single Family Building Upgrades
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Table 12. [Pre-1978] 3 kW PV without Solar Tax Credit (Std) Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
On-Bill Savings
On-Bill B/C
Modest Gas
Escalation
On-Bill NPV
Modest Gas
Escalation
On-Bill B/C
High Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $13,726 0.80 ($3,074) 0.85 ($2,410)
CZ02 PGE $13,726 0.80 ($3,072) 0.85 ($2,409)
CZ03 PGE $13,726 0.77 ($3,567) 0.81 ($2,930)
CZ04 PGE $13,726 1.11 $1,652 1.16 $2,564
CZ04 CPAU $13,726 1.38 $5,983 1.45 $7,123
CZ05 PGE $13,726 0.78 ($3,431) 0.82 ($2,786)
CZ05 PGE/SCG $13,726 0.78 ($3,431) 0.82 ($2,786)
CZ06 SCE/SCG $13,726 0.87 ($2,118) 0.92 ($1,231)
CZ07 SDGE $13,726 1.31 $4,886 1.30 $4,711
CZ08 SCE/SCG $13,726 1.30 $4,655 1.38 $5,984
CZ09 SCE/SCG $13,726 1.18 $2,821 1.26 $4,030
CZ10 SCE/SCG $13,726 1.29 $4,622 1.38 $5,948
CZ10 SDGE $13,726 1.99 $15,550 1.97 $15,284
CZ11 PGE $13,726 1.55 $8,684 1.64 $9,967
CZ12 PGE $13,726 1.07 $1,117 1.13 $2,002
CZ12 SMUD/PGE $13,726 0.93 ($1,109) 0.98 ($342)
CZ13 PGE $13,726 1.80 $12,597 1.90 $14,085
CZ14 SCE/SCG $13,726 1.58 $9,098 1.68 $10,717
CZ14 SDGE $13,726 2.15 $17,983 2.13 $17,695
CZ15 SCE/SCG $13,726 2.24 $19,477 2.39 $21,774
CZ16 PGE $13,726 1.04 $579 1.09 $1,435
2025 Energy Code: Existing Single Family Building Upgrades
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Table 13. [1978-1991] 3 kW PV without Solar Tax Credit (Std) Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
On-Bill Savings
On-Bill B/C
Modest Gas
Escalation
On-Bill NPV
Modest Gas
Escalation
On-Bill B/C
High Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $13,726 0.77 ($3,570) 0.81 ($2,932)
CZ02 PGE $13,726 0.71 ($4,549) 0.75 ($3,963)
CZ03 PGE $13,726 0.74 ($4,106) 0.78 ($3,497)
CZ04 PGE $13,726 1.00 $7 1.05 $833
CZ04 CPAU $13,726 1.35 $5,517 1.42 $6,633
CZ05 PGE $13,726 0.75 ($3,985) 0.79 ($3,369)
CZ05 PGE/SCG $13,726 0.75 ($3,985) 0.79 ($3,369)
CZ06 SCE/SCG $13,726 0.73 ($4,249) 0.78 ($3,501)
CZ07 SDGE $13,726 1.17 $2,623 1.16 $2,466
CZ08 SCE/SCG $13,726 1.20 $3,086 1.27 $4,313
CZ09 SCE/SCG $13,726 1.09 $1,487 1.17 $2,609
CZ10 SCE/SCG $13,726 1.18 $2,884 1.26 $4,097
CZ10 SDGE $13,726 1.85 $13,356 1.84 $13,108
CZ11 PGE $13,726 1.41 $6,420 1.48 $7,583
CZ12 PGE $13,726 0.97 ($512) 1.02 $287
CZ12 SMUD/PGE $13,726 0.93 ($1,109) 0.98 ($342)
CZ13 PGE $13,726 1.63 $9,953 1.72 $11,302
CZ14 SCE/SCG $13,726 1.42 $6,655 1.52 $8,115
CZ14 SDGE $13,726 2.00 $15,653 1.98 $15,386
CZ15 SCE/SCG $13,726 1.94 $14,686 2.06 $16,670
CZ16 PGE $13,726 0.95 ($737) 1.00 $49
2025 Energy Code: Existing Single Family Building Upgrades
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Table 1414. [1992-2010] 3 kW PV without Solar Tax Credit (Std) Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
On-Bill Savings
On-Bill B/C
Modest Gas
Escalation
On-Bill NPV
Modest Gas
Escalation
On-Bill B/C
High Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $13,726 0.71 ($4,475) 0.75 ($3,885)
CZ02 PGE $13,726 0.73 ($4,198) 0.77 ($3,593)
CZ03 PGE $13,726 0.72 ($4,411) 0.76 ($3,817)
CZ04 PGE $13,726 0.80 ($3,121) 0.84 ($2,459)
CZ04 CPAU $13,726 1.16 $2,477 1.22 $3,433
CZ05 PGE $13,726 0.73 ($4,299) 0.76 ($3,700)
CZ05 PGE/SCG $13,726 0.73 ($4,299) 0.76 ($3,700)
CZ06 SCE/SCG $13,726 0.61 ($6,143) 0.65 ($5,520)
CZ07 SDGE $13,726 0.94 ($931) 0.93 ($1,057)
CZ08 SCE/SCG $13,726 0.98 ($242) 1.05 $767
CZ09 SCE/SCG $13,726 0.88 ($1,890) 0.94 ($988)
CZ10 SCE/SCG $13,726 0.96 ($676) 1.02 $305
CZ10 SDGE $13,726 1.51 $8,054 1.50 $7,852
CZ11 PGE $13,726 1.10 $1,569 1.16 $2,477
CZ12 PGE $13,726 0.80 ($3,169) 0.84 ($2,510)
CZ12 SMUD/PGE $13,726 0.93 ($1,109) 0.98 ($342)
CZ13 PGE $13,726 1.27 $4,170 1.33 $5,215
CZ14 SCE/SCG $13,726 1.15 $2,295 1.22 $3,470
CZ14 SDGE $13,726 1.66 $10,386 1.65 $10,164
CZ15 SCE/SCG $13,726 1.37 $5,788 1.46 $7,191
CZ16 PGE $13,726 0.81 ($3,006) 0.85 ($2,338)
2025 Energy Code: Existing Single Family Building Upgrades
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Table 1515. [Pre-1978] 3 kW PV without Solar Tax Credit (CARE) Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
On-Bill Savings
On-Bill B/C
Modest Gas
Escalation
On-Bill NPV
Modest Gas
Escalation
On-Bill B/C
High Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $13,726 0.62 ($6,030) 0.65 ($5,522)
CZ02 PGE $13,726 0.64 ($5,707) 0.67 ($5,182)
CZ03 PGE $13,726 0.60 ($6,344) 0.63 ($5,853)
CZ04 PGE $13,726 0.83 ($2,725) 0.87 ($2,042)
CZ05 PGE $13,726 0.60 ($6,266) 0.63 ($5,771)
CZ05 PGE/SCG $13,726 0.60 ($6,266) 0.63 ($5,771)
CZ06 SCE/SCG $13,726 0.71 ($4,578) 0.75 ($3,852)
CZ07 SDGE $13,726 0.71 ($4,508) 0.71 ($4,604)
CZ08 SCE/SCG $13,726 0.97 ($483) 1.03 $510
CZ09 SCE/SCG $13,726 0.90 ($1,530) 0.96 ($605)
CZ10 SCE/SCG $13,726 0.97 ($465) 1.03 $530
CZ10 SDGE $13,726 1.19 $3,032 1.18 $2,872
CZ11 PGE $13,726 1.07 $1,150 1.13 $2,036
CZ12 PGE $13,726 0.79 ($3,324) 0.83 ($2,673)
CZ13 PGE $13,726 1.23 $3,587 1.29 $4,601
CZ14 SCE/SCG $13,726 1.17 $2,662 1.25 $3,861
CZ14 SDGE $13,726 1.28 $4,436 1.27 $4,264
CZ15 SCE/SCG $13,726 1.57 $8,962 1.67 $10,572
CZ16 PGE $13,726 0.79 ($3,342) 0.83 ($2,692)
2025 Energy Code: Existing Single Family Building Upgrades
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Table 1616. [1978-1991] 3 kW PV without Solar Tax Credit (CARE) Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
On-Bill Savings
On-Bill B/C
Modest Gas
Escalation
On-Bill NPV
Modest Gas
Escalation
On-Bill B/C
High Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $13,726 0.60 ($6,343) 0.63 ($5,851)
CZ02 PGE $13,726 0.56 ($6,845) 0.59 ($6,380)
CZ03 PGE $13,726 0.57 ($6,757) 0.60 ($6,287)
CZ04 PGE $13,726 0.76 ($3,715) 0.80 ($3,085)
CZ05 PGE $13,726 0.57 ($6,686) 0.60 ($6,213)
CZ05 PGE/SCG $13,726 0.57 ($6,686) 0.60 ($6,213)
CZ06 SCE/SCG $13,726 0.61 ($6,195) 0.64 ($5,575)
CZ07 SDGE $13,726 0.62 ($6,004) 0.61 ($6,087)
CZ08 SCE/SCG $13,726 0.91 ($1,483) 0.96 ($555)
CZ09 SCE/SCG $13,726 0.85 ($2,368) 0.90 ($1,497)
CZ10 SCE/SCG $13,726 0.90 ($1,597) 0.96 ($676)
CZ10 SDGE $13,726 1.10 $1,560 1.09 $1,413
CZ11 PGE $13,726 0.98 ($295) 1.03 $515
CZ12 PGE $13,726 0.72 ($4,320) 0.76 ($3,722)
CZ13 PGE $13,726 1.12 $1,893 1.18 $2,818
CZ14 SCE/SCG $13,726 1.07 $1,051 1.14 $2,144
CZ14 SDGE $13,726 1.18 $2,878 1.17 $2,719
CZ15 SCE/SCG $13,726 1.37 $5,735 1.45 $7,135
CZ16 PGE $13,726 0.74 ($4,126) 0.78 ($3,517)
2025 Energy Code: Existing Single Family Building Upgrades
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Table 1717. [1992-2010] 3 kW PV without Solar Tax Credit (CARE) Climate
Zone
Electric/ Gas
Utility
First
Incremental
Cost
On-Bill Savings
On-Bill B/C
Modest Gas
Escalation
On-Bill NPV
Modest Gas
Escalation
On-Bill B/C
High Gas
Escalation
On-Bill NPV
High Gas
Escalation
CZ01 PGE $13,726 0.56 ($6,963) 0.59 ($6,504)
CZ02 PGE $13,726 0.26 ($11,640) 0.20 ($12,611)
CZ03 PGE $13,726 0.55 ($6,997) 0.58 ($6,540)
CZ04 PGE $13,726 0.62 ($5,900) 0.66 ($5,385)
CZ05 PGE $13,726 0.56 ($6,932) 0.59 ($6,471)
CZ05 PGE/SCG $13,726 0.56 ($6,932) 0.59 ($6,471)
CZ06 SCE/SCG $13,726 0.51 ($7,652) 0.55 ($7,127)
CZ07 SDGE $13,726 0.48 ($8,115) 0.48 ($8,180)
CZ08 SCE/SCG $13,726 0.78 ($3,430) 0.83 ($2,629)
CZ09 SCE/SCG $13,726 0.72 ($4,462) 0.76 ($3,728)
CZ10 SCE/SCG $13,726 0.76 ($3,748) 0.81 ($2,968)
CZ10 SDGE $13,726 0.86 ($2,225) 0.85 ($2,340)
CZ11 PGE $13,726 0.79 ($3,259) 0.83 ($2,605)
CZ12 PGE $13,726 0.63 ($5,876) 0.66 ($5,359)
CZ13 PGE $13,726 0.89 ($1,678) 0.94 ($941)
CZ14 SCE/SCG $13,726 0.89 ($1,676) 0.95 ($761)
CZ14 SDGE $13,726 0.95 ($838) 0.94 ($964)
CZ15 SCE/SCG $13,726 0.99 ($142) 1.06 $873
CZ16 PGE $13,726 0.63 ($5,850) 0.66 ($5,333)
2025 Energy Code: Existing Single Family Building Upgrades
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6 References
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 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 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
Statewide CASE Team. (2020). Residential Energy Savings and Process Improvements for Additions and Alterations.
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
2025 Energy Code: Existing Single Family Building Upgrades
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Statewide Reach Codes Team. (2021). 2019 Cost-Effectiveness Study: Existing Single Family Residential Buidling Upgrades. Retrieved from
https://localenergycodes.com/content/resources
2025 Energy Code: Existing Single Family Building Upgrades
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