Fairfax City Council
October 15, 2025

FAIRFAX TOWN COUNCIL MEETING

SUPPLEMENTAL STAFF REPORT
1 SUPPLEMENT TO AGENDA ITEM #4
MEETING DATE October 15, 2025
PREPARED FOR Mayor and Town Council
PREPARED BY Mark Lockaby, Building Official
Bridget Wipfler, Climate Action Coordinator
SUBJECT Supplement to Agenda Item #4

RECOMMENDATION
• Add the following attachments to the staff report:

ATTACHMENTS
Attachment 1: Ordinance No. 901
Attachment 2: 2022 Cost-Effectiveness Study: Existing Single Family Building Upgrades Attachment 3: Application of the 2022 Studies to the 2025 Energy Code: Existing Single Family Building Upgrades
Attachment 4: Green Building Chapter Summary

ATTACHMENT A
ORDINANCE NO. 901

AN ORDINANCE OF THE TOWN COUNCIL OF THE TOWN OF FAIRFAX AMENDING CHAPTER 15.04 OF THE FAIRFAX TOWN CODE AND ADOPTING BY REFERENCE THE 2025 CALIFORNIA BUILDING STANDARDS CODE, INCLUDING THE 2025 CALIFORNIA ADMINISTRATIVE CODE, THE 2025 CALIFORNIA BUILDING CODE, THE 2025 CALIFORNIA RESIDENTIAL CODE, THE 2025 CALIFORNIA ELECTRICAL CODE, THE 2025 CALIFORNIA MECHANICAL CODE, THE 2025 CALIFORNIA PLUMBING CODE, THE 2025 CALIFORNIA ENERGY CODE, THE 2025 CALIFORNIA HISTORICAL BUILDING CODE, THE 2025 CALIFORNIA EXISTING BUILDING CODE, THE 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE, AND THE 2025 CALIFORNIA REFERENCED STANDARDS CODES, WITH LOCAL AMENDMENTS, AND THE 2024

EDITION OF THE INTERNATIONAL PROPERTY MAINTENANCE CODE
WHEREAS, the Town of Fairfax initiated proposed amendments to Fairfax Town Code Chapter

15.04 (Building Code). The Building Code includes building and energy efficiency regulations that apply to the incorporated areas of Fairfax. The project includes proposed amendments including, but not limited to, modifying green building requirements for new single family and duplex structures, new multi-family projects, new non-residential buildings or additions, remodeling and additions to residential structures, remodeling of multi-family projects, and remodeling to nonresidential structures; and WHEREAS, an inventory of 2020 greenhouse gas emissions for the Town of Fairfax found that the use of energy in residential and non-residential buildings within the Town generates 39% of the total annual greenhouse gas emissions, 90% of which comes from the combustion of natural gas in buildings; and
WHEREAS, the Town of Fairfax Climate Action Plan 2030 identifies reducing building energy use, and specifically natural gas use, as one of the most effective means of meeting the adopted goal of reducing the emissions of greenhouse gases to 100% below 2005 levels by the year 2030; and WHEREAS, the Town Council adopted a resolution on March 6, 2019, declaring a climate emergency and reaffirming the Town’s commitment to reducing greenhouse gas emissions; and WHEREAS, the California Global Warming Solutions Act of 2006, known as AB 32, established a statewide goal of reducing greenhouse gas emissions to 1990 levels by 2020 and to a level 80% below 1990 levels by 2050, and Senate Bill 32, passed in 2016, set a target to reduce statewide emissions to 40% below 1990 levels by 2030; and WHEREAS, the State of California Air Resource Board Draft 2025 Scoping Plan states that greenhouse gas reductions from local efforts are important to support state-level measures and highlights building decarbonization as a priority strategy for greenhouse gas reduction; and WHEREAS, through Senate Bill 100 the State of California has adopted a goal that renewable energy and zero-carbon resources supply 100 percent of electric retail sales to end-use customers by 2045; and
WHEREAS, Fairfax properties can currently access 100% renewable energy via MCE’s Deep Green and PG&E’s Solar Choice programs, and MCE expects to achieve 95% GHG-free by 2023 for their Light Green service; and

WHEREAS, the Town of Fairfax is already experiencing and at risk of more frequently experiencing the devastating effects of extreme heat and weather events and flooding caused by climate change, including increased frequency and magnitude of wildfires and associated air pollution, health impacts, utility and transportation service interruptions, economic disruption, property loss, dislocation, housing shortages, food insecurity, school closures, impacts on agricultural production; and increased demand on public sector resources and emergency response capacity; and
WHEREAS, California Health and Safety Code Section 17958.7 provides that before making any local changes or modifications to the California Building Standards Code (CBSC) pursuant to Section 17958.7, the governing body must make an express finding that such modifications or changes are reasonably necessary because of local climatic, geological or topographical conditions, that such findings must be available as a public record, that a copy of the findings together with the modifications or changes expressly marked and identified to which each finding refers, must be filed with the State Building Standards Commission, and that no modification or change shall become effective or operative for any purpose until the findings and the modifications or changes have been filed with the Commission, and that the Commission may reject a modification or change if no finding was submitted; and WHEREAS, the Town Council hereby finds that the green building local modifications to California Green Building Standards Code Chapters 3, 4, and 5, as set forth in this ordinance, are reasonably necessary to address local climatic, geologic, environmental, and/or topographic conditions that affect the health, safety, and welfare of residents; and WHEREAS, the Town of Fairfax is the designated enforcement authority for this Title, and with the Ordinance proposed herein is expressly initiating local amendments, additions or deletions to the California Building Standards Code; and
WHEREAS, the Public Resources Code Section 25402.1(h)(2) states that a local enforcement agency may adopt more restrictive energy standards when they are cost-effective and approved by the California Energy Commission; and
WHEREAS, The Town of Fairfax first adopted a green building and energy reach code in 2010 and most recently, in the fall of 2022, the Town Council adopted an energy and electrification reach code for residential additions and alterations (also known as the Flex Path) that went into effect on January 1, 2023.

WHEREAS, The proposed amendments to the Building Code are substantially equivalent to the amendments to the Building Code that were adopted by the Town Council in November 2022 and went into effect January 1, 2023.

WHEREAS, the Town Council hereby determines that the revised energy standards contained herein are cost effective, based upon the findings of studies conducted by Frontier Energy, Inc., Misti Bruceri & Associates LLC, and TRC Energy Services; and WHEREAS, nothing in this ordinance is intended to amend or conflict with any provisions of the National Appliance Energy Conservation Act of 1975 or to impose requirements to use or install any particular appliance or appliance system.

THE TOWN OF FAIRFAX DOES ORDAIN AS FOLLOWS:

SECTION 1. Findings. The Town Council finds that in order to best protect the health, safety and welfare of the citizens of the Town of Fairfax, the standards of building within the Town must conform with state law except where local conditions warrant more restrictive regulations, and, therefore, the Town Council should adopt the current California Building Standards Codes, contained in California Code of Regulations, Title 24, and other uniform codes governing the construction and regulation of buildings and structures, along with certain local changes and modifications to these Codes, which the Town Council is authorized to make by California Health and Safety Code Sections 17958.7, and 18941.5, and reasonably necessary due to local climatic, geological, or topographical conditions.

Additional amendments are found to be either administrative or procedural in nature or to concern themselves with subjects not covered in the Codes. They are necessary for administrative clarification, and do not modify a building standard pursuant to California Health & Safety Code Sections 17958, 17958.7, and/or 18941.5. These administrative amendments establish administrative standards for the effective enforcement of the building standards in the Town. The changes made include provisions making each of said Codes compatible with other codes enforced by the Town and fee schedules.

A copy of this Ordinance adopting the 2025 California Building Standards Code, as amended, shall be filed with the California Building Standards Commission by the Town Clerk of the Town of Fairfax.

Pursuant to California Health and Safety Code section 17958.7, the Town Council makes the factual findings set forth in “Exhibit A” attached hereto and incorporated herein by reference, and finds that the amendments made in this ordinance to the California Building Code, California Code of Regulations, Title 24, Part 2, and California Residential Code, California Code of Regulations, Title 24, Part 2.5, and the California Plumbing Code, California Code of Regulations, Title 24, Part 5, are reasonably necessary because of the local climatic, geological or topographical conditions stated in Exhibit A.

The Town Council of the Town of Fairfax further finds that adoption of this ordinance is exempt from the California Environmental Quality Act (CEQA) under California Code of Regulations, Title 14, § 15061(b)(3). Furthermore, the project protects persons and property from emergencies caused by the risk of fire, explosion and earthquake, and is statutorily exempt from CEQA because it is an action necessary to prevent or mitigate an emergency. (Cal. Public Resources Code section 21080(b)(4).)
SECTION 2. Chapter 15.04 of the Municipal Code Amended. Chapter 15.04 of the Town Code is hereby deleted in its entirety and replaced by the following:
“Chapter 15.04

BUILDINGS AND CONSTRUCTION
Sections

15.04.010 Adoption of Construction Codes

15.04.015 Definitions

15.04.020 Automatic Fire Sprinkler Systems, Fire Extinguishers, Smoke Alarms

15.04.025 Plan Check Fees

15.04.030 Roof Coverings

15.04.035 Barriers for swimming pools, spas, and hot tubs

15.04.040 Septic Systems

15.04.045 Correcting Past Violations

15.04.050 Fee Adjustments

15.04.055 Alternative Power Supplies

15.04.060 Applicability of 2025 Wildland Urban Interface Code

15.04.065 Electric Vehicle Charging Stations

15.04.070 Green Building Requirements

15.04.075 Requirements for additions and alterations; Local amendments to 2025 California Energy Code

15.04.085 Standards for compliance

15.04.090 Incentives for compliance

15.04.095 Administrative Procedures

15.04.100 Exemptions

Section 15.04.010 – Adoption of Construction Codes
The following parts of Title 24, California Code of Regulations are adopted by reference as construction codes for the Town of Fairfax, subject to the modifications included later in this title:
a) 2025 California Administrative Code (Title 24, Part 1) b) 2025 California Building Code (Title 24, Part 2) based upon the 2024 International Building Code (IBC), including:
1) Division II of Chapter 1, but not Section 113,
2) Appendix Chapter A, Employee Qualifications,
3) Appendix Chapter G, Flood-Resistant Construction,
4) Appendix Chapter H, Signs,
5) Appendix Chapter I, Patio Covers, and
6) Appendix Chapter J, Grading.
c) 2025 California Residential Code (Title 24, Part 2.5) based on the 2024 International Residential Code (IRC) including:
1) Division II of Chapter 1, but not Section 112,
2) Appendix BF Patio Covers
3) Appendix BH Automatic Vehicular Gates
4) Appendix BL Hemp Line (Hempcrete) Construction
5) Appendix BO Existing Buildings and Structures
6) Appendix CI Swimming Pool Safety Act
d) 2025 California Electrical Code (Title 24, Part 3) based upon the 2023 National Electrical Code (NEC), including:

1) Article 89, but not Section 89.108.8.
e) 2025 California Mechanical Code (Title 24, Part 4) based upon the 2024 Uniform Mechanical Code (UMC), including:
1) Division II of Chapter 1, but not Sections 107.0, 107.1, 107.2. f) 2025 California Plumbing Code (Title 24, Part 5) based upon the 2024 Uniform Plumbing Code (UPC), including:
1) Division II of Chapter 1, but not Sections 107.0, 107.1, or 107.2 g) 2025 California Energy Code (Title 24, Part 6)
h) 1) Division II of Chapter 1, but not Section 112
i) 2025 California Historical Building Code (Title 24, Part 8) j) 2025 California Existing Building Code (Title 24, Part 10) based upon the 2024 International Existing Building Code (IEBC) including the following chapters of Appendix A (Guidelines for the Seismic Retrofit of Existing Buildings):
1) Chapter A1 Seismic Strengthening Provisions for Unreinforced Masonry Bearing Wall Buildings;
2) Chapter A3 Prescriptive Provisions for Seismic Strengthening of Cripple Walls and Sill Plate Anchorage of Light, Wood-Framed Residential Buildings; and,
3) Chapter A4 Earthquake Risk Reduction in Wood-Frame Residential Buildings With Soft, Weak or Open Front Walls.
k) 2025 California Green Building Standards Code (CALGreen) (Title 24, Part 11), including:
1) Appendix A4 and Appendix A5 Tier 1 measures, but excluding Appendix A4.2 and A5.2 (Energy Efficiency). The Tier 1 measures shall be mandatory for commercial and residential construction, and verification of such compliance shall be provided by the installer or designer. l) 2025 California Referenced Standards Code (Title 24, Part 12). m) 2024 edition of the International Property Maintenance Code, to the extent the same is not inconsistent with the California Buildings Standards Code (California Code of Regulations, Title 12, Parts 1-12), as adopted and amended herein.

A copy of each of these documents is maintained in the office of the Building Official, and reference is made to them with like effect as if all the provisions and printed matter therein were herein set forth in full.

Section 15.04.015 – Definitions
Section 202 of the California Building Code and Section R202 of the California Residential Code are both hereby amended to add the definitions of “Second Unit” and “Substantial Remodel” as follows:

SECOND UNIT. A completely separate housekeeping unit with kitchen, sleeping and bathroom facilities which is a part of, an extension to, or a separate structure on a site

developed with a single-family residence, in excess of the maximum density designated by the zoning district in which the property is situated or as prescribed thereby.

SUBSTANTIAL REMODEL. The renovation of any structure, which combined with any additions to the structure, affects a floor area which exceeds fifty percent of the existing floor area of the structure within any twelve-month period. When any changes are made in the building, such as walls, columns, beams or girders, floor or ceiling joists and coverings, roof rafters, roof diaphragms, piles or retaining walls or similar components, the floor area of all rooms affected by such changes shall be included in computing floor areas for the purposes of applying this definition. This definition does not apply to the replacement and upgrading of residential roof coverings, repair or replacement of foundations, the installation of energy efficient windows of like size, or the removal of interior wall coverings solely for the installation of insulation.

Section 15.04.020 – Exterior Fire Resistive Construction, Automatic Fire Sprinkler Systems, Fire Extinguishers, Smoke Alarms.

Section 501.1 of the 2025 California Wildland-Urban Interface Code (Title 24, Part 7, California Code of Regulations) are hereby amended to read as follows:
501.1 Scope. This chapter applies to building materials, systems, and/or assemblies used in the exterior design and construction of new buildings, additions, repairs, and exterior alterations located within a Wildland Urban Interface Fire Area as defined in section 301.1 Section 501.1.1 is hereby added to Chapter 5 of the 2025 California Wildland-Urban interface Code (Title 24, Part 7, California Code of Regulations) are hereby amended to read as follows:
501.1.1 Application.. New buildings, additions, repairs, and exterior alterations to buildings located in any Fire Hazard Severity Zone or any Wildland Urban Interface Fire Area designated by the enforcing agency constructed after the application date shall comply with the provisions of this chapter.

Exceptions:

1. Buildings of an accessory character and not exceeding 120 square feet in floor area, when located at least 30 feet from an applicable building.

2. Buildings of an accessory character classified as a Group U occupancy of any size located at least 50 feet from an applicable building.

3. Buildings classified as a Group U Agricultural Building, as defined in Section 202 and R202 of this code (see also Appendix C - Group U Agricultural Buildings), when located at least 50 feet from an applicable building.

Section 504.5.3 is hereby added to Chapter 5 of the 2025 California Wildland-Urban Interface Code(Title 24, Part 7, California Code of Regulations), which shall read as follows:
504.5.3. When more than fifty percent (50%) of exterior wall coverings of an existing structure are repaired or replaced within a thirty-six (36) month period, the entire exterior wall coverings shall comply with Section 504.5.2.

Section 903.2 of the California Building Code is hereby amended to read as follows:

903.2 Where Required. All Occupancies and Facilities. Approved automatic sprinkler systems in new buildings and structures shall be provided in the locations described in Sections 903.2.1 through 903.2.12 and Sections 903.2.14 through 903.2.21. Additionally, an automatic fire sprinkler system shall be installed in all of the following:

1. Every newly constructed building and facility.

Exceptions:
a. Free standing Group U Occupancies not more than 1,000 square feet and provided with exterior wall and opening protection as per Table 602 of the California Building Code. b. Agricultural buildings as defined in Appendix C of the California Building Code and not exceeding 2,000 square feet, having clear unobstructed side yard of combustible materials,
exceeding 60 feet in all directions and not exceeding 25 feet in height.

2. In newly created second units.

Exceptions:
a. Parcels that are not within the Wildland Urban Interface Code, as established by the Town.
b. Parcels for which there is less than a thirty percent (30%) grade change between the subject parcel and Sir Francis Drake Boulevard as illustrated in the “Map of Parcels Qualifying for Exceptions to Sprinkler System Requirements for Newly
Created Second Units” or as hereafter designated by resolution of the Town of Fairfax.
c. Junior second units.
d. For an accessory dwelling unit, as defined by Government Code Section 66313, if fire sprinklers are not required for the primary residence. This exception is intended to comply with
Government Code Section 66314(C)

3. In all buildings which have more than fifty percent (50%) floor area added or any “substantial remodel” as defined in this code, within any 12 month period.

Exceptions may be granted by the Fire Code Official when alternate means of protection are installed as approved by the Fire Code Official.

4. In all buildings except R-3 occupancies, in excess of 3,000 sq. ft. which have more than ten percent (10%) floor area added within any 12 month period.

Exceptions may be granted by the Chief when alternate means of protection are installed as approved by the Fire Code Official.

5. A change in the use of a structure that results in a higher fire or life safety exposure when the square footage of the area changing use is more than fifty percent (50%) of the square footage of the building.

Section R309.1 and R309.2of the California Residential Code each amended to read as follows:

R309.1 / R309.2 Where Required. An automatic fire sprinkler system shall be installed in all of the following:

1. Every newly constructed building and facility.

Exceptions:
a. Free standing Group U Occupancies not more than 1,000 square feet and provided with exterior wall and opening protection as per Table 602 of the California Building Code.
b. Agricultural buildings as defined in Appendix C of the California Building Code and not exceeding 2,000 square feet, having clear unobstructed side yard of combustible materials, exceeding 60 feet in all directions and not exceeding 25 feet in height.

2. In newly created second units.

Exceptions:
a. Parcels that are not within the Wildland Urban Interface Code, as established by the Town.
b. Parcels for which there is less than a thirty percent (30%) grade change between the subject parcel and Sir Francis Drake Boulevard as shown on the “Map of Parcels Qualifying for Exceptions to Sprinkler System Requirements for Newly Created Second Units” or as hereafter designated by resolution of the Town of Fairfax.
c. Junior second units.
d. For an accessory dwelling unit, as defined by Government Code Section 66313 if fire sprinklers are not required for the primary residence. This exception is intended to comply with Government Code Section 66314(d) (12)

3. In all buildings which have more than fifty percent (50%) floor area added or any “substantial remodel” as defined in this code, within any 12 month period.

Exceptions may be granted by the Fire Code Official when alternate means of protection are installed as approved by the Fire Code Official.

4. In all buildings except R-3 occupancies, in excess of 3,000 sq. ft. which have more than ten per cent (10%) floor area added within any 12 month period.

Exceptions may be granted by the Chief when alternate means of protection are installed as approved by the Fire Code Official.

5. A change in the use of a structure that results in a higher fire or life safety exposure when the square footage of the area changing use is more than fifty percent (50%) of the square footage of the building.

Section 903.3 of the California Building Code and Sections R309.1.1 and R309.2.1 of the California Residential Code are each hereby amended by adding the following language to the end of each respective section:

The requirements for fire sprinklers in this code section are not meant to disallow the provisions for area increase, height increase, or Fire-Resistive substitution if otherwise allowed by sections 504 and 506 of the California Building Code. All automatic fire sprinkler systems shall be installed in accordance with the written standards of the Fire Code Official and the following:
a. In all residential buildings required to be sprinkled any attached garages shall be sprinkled, and except for one and two family dwellings, in all residential occupancies the attics shall be sprinkled.
b. In all existing buildings, where fire sprinklers are required by provisions of this code, they shall be extended into all unprotected areas of the building. c. All single family dwellings in excess of 5,000 square feet shall have automatic fire sprinkler systems designed in accordance with NFPA Standard 13 or 13R and standards developed by the Fire Chief.
d. All public storage facilities shall have installed an approved automatic fire sprinkler system. An approved wire mesh or other approved physical barrier shall be installed 18 inches below the sprinkler head deflector to prevent storage from being placed to within 18 inches from the bottom of the deflector measured at a horizontal plane.

Section 906.11 is hereby added to the California Building Code as follows:
906.11 Fire Extinguisher Documentation. The owner and/or operator of every Group R Division 1 and R Division 2 occupancies shall annually provide the Chief written documentation that fire extinguishers are installed and have been serviced as required by Title 19 of the California Code of Regulations when such extinguishers are installed in residential units in lieu of common areas.

Section 907.2 of the California Building Code is amended to add the following paragraphs after the second paragraph and before the Exceptions:

New Construction: Every new building constructed for non-residential occupancies greater than 2,000 square feet shall have installed therein an approved fire detection (products of combustion) system in accordance with the standards established by the National Fire Protection Association. The type of system installed shall be determined by the Fire Chief.

Existing Construction: Every existing building remodeled for non-residential occupancies greater than 2,000 square feet shall have installed therein an approved fire detection (products of combustion) system in accordance with the standards established by the National Fire Protection Association. The type of system installed shall be determined by the Fire Chief.

Section 907.2.11 is hereby amended by changing the first sentence of the exception to read as follows:

EXCEPTION: For group R occupancies other than single family dwellings.

Section 907.8.1 is hereby added as follows:

Section 907.8.1 Smoke Alarm Documentation. The owner and/or operator of every Group R Division 1, Division 2, Division 3.1, and Division 4 Occupancies shall annually provide the Fire Code Official with written documentation that the smoke alarms installed pursuant to the California Building Code have been tested and are operational. If alarms are found to be inoperable or are missing, such alarms shall be repaired or replaced immediately.

Section 15.04.025 – Plan Check Fees
Section 109.2 of the California Building Code is hereby amended to add the following:

When submittal documents are required by Section 107.1, a plan review fee shall be paid at the time of submitting the submittal documents for plan review. Said plan review fee shall be sixty-five percent (65%) of the building permit fee.

When private contractors are retained to conduct project plan checks, the plan check fee charged by the Town shall be the total cost of the private plan check plus an additional twenty percent (20%) of that cost to defer administrative services provided by the Town.

Section 15.04.030 – Roof Coverings
Section 1505.1 of the California Building Code and Section R902.1 of the California Residential Code are both amended to add the following language after the first paragraph and before the exception(s) to each:

Notwithstanding anything to the contrary, the roof covering on any structure regulated by this code shall be a Class A Roof Covering Assembly as classified by Section 1505.2. When more than fifty percent (50%) of the total roof area of an existing structure is replaced within a twelve (12) month period, the entire roof must be replaced with a Class A Roof Covering Assembly.

Section 15.04.035 – Barriers for Swimming Pools, Spas and Hot Tubs The Town Council finds and determines that the maintenance of swimming pools without protective measures constitutes a hazard to the safety of children and other inhabitants of the Town, and therefore the regulations contained in section 3109 of the California Building Code and Appendix CI of the California Residential Code, are hereby adopted and shall apply to existing as well as remodeled and new swimming pools.

Section 15.04.040 – Septic systems
California Plumbing Code Section 713.1 is amended to read as follows:

Every building in which plumbing fixtures are installed and every premises having drainage piping thereon, shall have a connection to a public sewer, except as provided in Sections 713.2 and 713.4.

Exception: A permit may be issued for the repair, replacement, or alteration of a previously constructed septic tank or sewage disposal system other than a septic system where no public sewer is available upon approval by the Town Council, the Planning Commission, the Marin County Health Department, Sanitary District Number 1 of Marin County, and the Bay Area Water Quality Control Board.

Section 15.04.045 – Correcting Past Violations
Before a new permit can be issued for any parcel, all expired permits for a parcel must be reinstated, all work done without a permit on a parcel must be permitted, and all mandatory correction items noted on the Resale Inspection Reports for that parcel must be permitted or corrected.

Section 109.7 is added to the California Building Code and Section R108.7 is added to the California Residential Code to read as follows:

Expired permits which are lacking only a final inspection may be reinstated for a fee of $50 or the cost of the permit, whichever is less.

Section 15.04.050 – Fee Adjustments.

The Town Council may, by resolution, revise the fees established by this Chapter 15.04.

Section 15.04.055 – Alternative Power Supplies
Section 1511.10.2 of the California Building Code and Section R329.8.4 of the California Residential Code are added to read as follows:

Alternative Power Supplies. Roof-mounted photovoltaic panels/modules and other alternative electrical power supply sources shall comply with the requirements of the California Building Code as amended, the California Residential Code as amended, the California Electrical Code, and the California Fire Code as amended.

Section 15.04.065 – Electric Vehicle Charging Stations
(A) Purpose. The purpose of this section is to create an expedited and streamlined electric vehicle charging station permitting process that complies with Cal. Government Code § 65850.7 to achieve the timely and cost-effective installation of electric vehicle charging stations. Pursuant to Cal. Gov't Code § 65850.7 and notwithstanding any other provision of this code pertaining to conditional or accessory uses, only an electrical permit shall be required for an electric vehicle charging station.
(B) Definitions.
“Electronic Submittal.” The submission of application materials via electronic mail. “Electric Vehicle Charging Station (EVCS)” means a parking space that includes installation of electric vehicle supply equipment (EVSE) at an EV Ready space. An EVCS

space may be used to satisfy EV Ready space requirements. EVSE shall be installed in accordance with the California Electrical Code, Article 625. (C) Permit.
(1) An electrical permit is required prior to installing an electric vehicle charging station. Installation shall also meet any applicable requirements of the California Building Standards Code (California Code of Regulations, Title 24) and state law, including but not limited to, Cal. Gov't Code § 65850.7, as may be amended from time to time. (2) The Building Official shall adopt and maintain a standard electric vehicle charging station checklist that is consistent with the checklist in the most current version of the "Plug-In Electric Vehicle Infrastructure Permitting Checklist" of the "Zero-Emission Vehicles in California: Community Readiness Guidebook" published by the Office of Planning and Research. The checklist and application shall be made available on the town's website.
(3) An application to install an electric vehicle charging station may be made by electronic submittal. An applicant's electronic signature shall be accepted on all forms, applications, and other documents in lieu of a wet signature. (4) An application will be deemed complete if the Building Official determines that the application includes all of the information and documents required by the standard application form and the standard checklist. If an application is deemed incomplete, the Building Official will notify the applicant in writing of the additional information needed to complete the application. After an application is deemed complete, the Building Official will perform an expedited review of the application.
(5) Review of the permit application shall be limited to the Building Official's review of whether the application meets local, state and federal health and safety requirements.

The application shall be administratively reviewed by the Building Official as a ministerial permit.
(6) Approval of a permit shall not be conditioned on the approval of an association, as that term is defined in Cal. Civil Code § 4080.
(7) A permit will be issued following the Building Official's approval of an application for an electric vehicle charging station and after all required fees have been paid. If the application was submitted electronically, the permit may be issued electronically. The decision to approve or deny the permit shall be issued in accordance with the timeframes adopted by the Town Council and in no event later than three days after the application is deemed complete.
(8) As soon as practicable after the applicant notifies the Building Official that an electric vehicle charging station has been installed, the Building Official will inspect the system to verify compliance with the permit. No electric vehicle charging station may be operated unless the Building Official verifies in writing that it complies with the permit.

Section 15.04.070 – Green Building Requirements

(A) Purpose. The purpose of this section is to meet or exceed all applicable mandatory measures of the 2025 California Green Building Standards Code (Title 24, Part 11) of the California Code of Regulations and to enhance the long-term public health and welfare by contributing to the overall reduction of greenhouse gas emissions and improving the environmental and economic health of the county through the efficient design, construction, operation, maintenance and deconstruction of buildings and site development by incorporating green building practices and materials. The green building provisions referenced in this chapter are designed to achieve the following objectives:
(1) Increase energy efficiency in buildings;
(2) Reduce consumption of fossil fuels in the Town;
(3) Encourage water and resource conservation;
(4) Reduce waste generated by construction projects;
(5) Reduce long-term building operating and maintenance costs; (6) Improve indoor air quality and occupant health;
(7) Contribute to meeting state and local commitments to reduce greenhouse gas emissions; and
(8) Satisfy all applicable mandatory measures of the 2025 California Green Building Standards Code (Title 24, Part 11) of the California Code of Regulations. (B) Applicability.

The provisions of this section shall apply to all construction or development projects defined below as a “covered project.”
(C) Definitions.

For the purposes of interpreting this chapter and the associated standards for compliance, the following terms are defined as follows. When the definitions below differ from those contained elsewhere in this title, the provisions of this chapter shall apply. These definitions are additional to those outlined in Chapter 2 of the California Green Building Standards Code, Title 24, Part 11.
(1) "2025 California Energy Code" refers to the requirements outlined in the 2025 edition of the California Energy Code known as California Code of Regulations, Part 6 of Title 24.
(2) "All-electric Building" or “All-electric Design” means a building or plans for a building that uses a permanent supply of electricity as the source of energy for all space heating (including but not limited to fireplaces), water heating (including but not limited to pools and spas), cooking appliances, and clothes drying appliances, and has no natural gas or propane plumbing installed in the building or within the property lines. An all-electric building may also include solar thermal collectors.
(3) “Accessory Dwelling Unit (ADU)” means a residential unit that meets the definition of an accessory dwelling unit as outlined in Chapter 17 of the Fairfax Town Code . This states that “a residential dwelling unit, which is accessory to a primary dwelling unit, that provides complete independent living facilities for one or more persons and is located on a lot with a proposed or existing primary dwelling. It shall provide permanent provisions for living, sleeping, eating, cooking, sanitation, and independent exterior access, on the same lot as the single-family or multi-family dwelling is or will be situated. An Accessory

Dwelling Unit also includes the following: (1) an efficiency unit as defined in section 17958.1 of the California Health and Safety Code and (2) a manufactured home as defined in section 18007 of the California Health and Safety Code.” For purposes of this subchapter, ADU also covers Junior ADUs and detached or attached ADUs. (4) "CALGreen" refers to the California Green Building Standards Code, as included in Title 24, Part 11 of the California Code of Regulations. (5) "CALGreen mandatory" means those measures that are required under Title 24, Part 11. Residential mandatory measures are contained in CALGreen Chapter 4.

Nonresidential mandatory measures are contained in CALGreen Chapter 5. (6) "CALGreen Tier 1" refers to required pre-requisite and elective measures in addition to the CALGreen mandatory measures, as outlined in CALGreen Appendix A4.601.4 for residential projects and CALGreen Appendix A5.601.2 for nonresidential projects.
(7) "Covered Project(s)" means a development project provided below as set forth by the standards for compliance outlined in § 15.04.085, Table 1, 2, or 3 for which one or more building permits are required:
(i) Additions or alterations to an existing single-family residential building. (ii) Additions or alterations to an existing multi-family residential building, hotel, or motel.
(8) “Mixed-fuel” means a building or unit in a building that is plumbed for the use of natural gas or propane as fuel for space heating, water heating, cooking or clothes drying appliances or has gas plumbing within a building or within the property lines of the premises connected to a gas meter or propane tank.
(9) “Natural gas” has the same meaning as "Fuel Gas" as defined in the California Plumbing Code and Mechanical Code.
(10) “Newly Constructed” means a building that has never before been used or occupied for any purpose.
(11) "Qualified green building rater" means an individual who has been trained and certified as a CALGreen inspector, LEED AP w/a specialty, GreenPoint rater, PHIUS consultant, or has similar qualifications and certifications if acceptable to the chief building official.
(12) “Single-Family” means a building designed for and/or occupied exclusively by one family. It is used herein to describe one and two-family dwellings and townhouses with attached private garages. It also includes factory-built, modular housing units, constructed in compliance with the California Building Code (CBC), and mobile homes/manufactured housing on permanent foundations and agricultural worker housing.

15.04.075 – Requirements for additions and alterations; Local amendments to 2025 California Energy Code

Pursuant to §15.04.010(g), Fairfax has adopted the 2025 Edition of the California Energy Code known as California Code of Regulations, Part 6 of Title 24, with additions and deletions as provided in this subchapter.

The provisions of this subchapter shall constitute local amendments to the cross-referenced provisions of the 2025 California Energy Code and shall be deemed to replace the crossreferenced sections of said Code with the respective provisions set forth in this subchapter.

The California Energy Code, Title 24, Part 6, is hereby amended provided below:

Section 100.0 of Subchapter 1 of the 2025 California Energy Code is modified to add new section (i) as follows:
(i) Single-Family Building Remodel Energy Reach Code - Purpose and Intent. In addition to all requirements of the California Energy Code applicable to Existing Single-Family Building additions and alterations, the energy efficiency and renewable energy measures specified in Section 150.0(w) shall be required for Covered Projects of mixed-fuel buildings.

Section 100.1(b) is modified by adding the following definitions:
"All-electric Building" or “All-electric Design” as defined in § 15.04.070(C)(2), Fairfax Town Code.
"Covered Project(s)" as defined in § 15.04.070(C)(7), Fairfax Town Code. “Mixed-fuel” building as defined in § 15.04.070(C)(8), Fairfax Town Code.

Section 150.0 SINGLE-FAMILY RESIDENTIAL BUILDINGS – MANDATORY FEATURES AND DEVICES, first two paragraphs, are modified to read as follows:

Existing Single-Family residential buildings shall comply with the applicable requirements of Sections 150.0(a) through 150.0(v), and Covered Existing Single-Family Projects, other than projects identified as all-electric construction for newly constructed or new construction buildings in § 15.04.070(C)(2) of the Fairfax Town Code, shall comply with the applicable requirements of Section 150.0(w).

NOTE: The requirements of Sections 150.0(a) through 150.0(v) apply to newly constructed buildings. Sections 150.2(a) and 150.2(b) specify which requirements of Sections 150.0(a) through 150.0(v) also apply to additions or alterations. In addition, Covered Existing Single-Family Projects shall also be required to comply with Section 150.0(w).

Section 150.0(w) is added to read as follows
(w) Requirements for a Covered Project are outlined by project type in §15.04.085, Table 1, Fairfax Town Code. A Covered Existing Single-Family Project, as defined in § 15.04.070(C)(7) of the Fairfax Town Code, in a building originally permitted for construction on or before December 31, 2010, shall install a set of measures from the Measure Menu in § 15.04.085, Table 2, Fairfax Town Code, to achieve a total Measure Point Score that is equal to or greater than the Target Score in said table

and shall conform to the List of Measure Specifications in § 15.04.085, Table 3, Fairfax Town Code, except as otherwise described below:
(i) Projects in buildings identified as all-electric as defined in §15.04.070(C)(2) of the Fairfax Town Code.
(ii) Projects less than 200 square feet. Square footage associated with the creation of a new ADU or JADU will not be included in the calculation of project square footage.
(iii) Projects that are limited solely to a newly created attached ADU or JADU as defined in § 15.04.070(C)(3) of the Fairfax Town Code. A newly created ADU and JADU shall include either additions or conversions of existing space. This exception DOES NOT apply to a Covered Existing Single-Family Project of an existing ADU or JADU.
(iv) Mobile Homes, Manufactured Housing, or Factory-built Housing as defined in Division 13 of the California Health and Safety 12 Code (commencing with section 17000 of the Health and Safety Code). (v) If due to conditions specific to the project, it is technically or economically infeasible to achieve compliance, the chief building official may reduce the Target Score and/or waive some or all of the mandatory requirements.
(vi) If the applicant demonstrates that the Energy Budget of the proposed building, as calculated under Section 150.1(b), would be less than or equal to the Energy Budget of the building if it otherwise complied with this Section 150.0(w).
(vii) A resident owner or occupant demonstrates that they qualify for the California Alternative Rates for Energy (CARE) or Family Electric Rate Assistance (FERA) program may comply by installing, to the specifications in § 15.04.085, Table 3 of the Fairfax Town Code, the following:
(a) E1: Lighting Measures; and
(b) E2: Water Heating Package
Unless otherwise specified, the requirements shall apply to the entire dwelling unit, not just the additional or altered portion. Measures from the Measure Menu table that are to be installed to satisfy requirements under the California Energy Code, Title 24, Part 6, may not count towards compliance with these requirements. Where these requirements conflict with other California Energy Code requirements, the stricter requirements shall prevail.

In addition, all mandatory measures listed in §15.04.085, Table 2 of the Fairfax Town Code, shall be installed.

Measure verification shall be explicitly included as an addendum to the Certificate of Compliance to be filed pursuant to 2025 Title 24, Part 6, Section 10-103.

Section 301.1 of Chapter 3 of the 2025 CALGreen Code is hereby amended as underlined and struck through:
301.1 Scope. Buildings shall be designed to comply with applicable requirements of Town of Fairfax Green Building Requirements beginning at Chapter 15.04.065(A), Fairfax Town Code, and shall also include the green building measures specified as mandatory in the application checklists contained in this code.

15.04.085 Standards for compliance.

The Town of Fairfax Green Building Requirements contain compliance thresholds for different projects that are covered by this chapter. These standards are summarized below in Table 1. The energy efficiency and electrification measures menu and specifications are detailed in Tables 2 and 3.

Table 1: Requirements by Project Type and Size
Project
Type
and Size
Green Building
Requirements
Energy
Efficiency
Requirements
Electric
Vehicle
Requirements
Single and
Two-Family
Newly
Constructed or
New
Construction
CALGreen Tier 1
except Energy
Measures
Meet the
standards
outlined for the
project in the
2025 California
Energy Code
CAL Green Tier 1
Multifamily
Residential
Newly
Constructed or
New
Construction
Nonresidential
Newly
Constructed or
New
Construction
CALGreen Tier 1
Except Energy
Efficiency Measures
Meet the
standards
outlined for the
project in the
2025 California
Energy Code
CALGreen Tier 1
Single and
Two-Family
Additions and
Alterations less
than 200
square feet
CALGreen Mandatory Meet the
standards
outlined for the
project in the
2025 California
Energy Code
CALGreen Mandatory

Table 1: Requirements by Project Type and Size
Project
Type
and Size
Green Building
Requirements
Energy
Efficiency
Requirements
Electric
Vehicle
Requirements
Single and
Two-Family
Additions and
Alterations 200
square feet or
greater
CALGreen Tier 1
Except the Energy
Efficiency Measures
Using the
Measure Menu
in Table 2,
achieve a total
score that is
equal to or
greater than the
Target Score for
the applicable
climate zone
CALGreen Tier 1
Multifamily
Residential
Additions and
Alterations less
than 200
square feet
CALGreen Mandatory Meet the
standards
outlined for the
project in the
2025 California
Energy Code
CALGreen Mandatory
Multifamily
Residential
Additions and
Alterations 200
square feet or
greater
CALGreen Tier 1
Except Energy
Efficiency Measures
CALGreen Tier 1
Nonresidential
Additions and
Alterations
The following conditions also apply to Table 1:
(a) Cumulative new construction or remodels during the preceding 36-month period from the acceptance of this application shall be considered as a single covered project, and subject to the highest compliance threshold based on the cumulative project size or valuation.
(b) Mixed use (residential and commercial) projects must comply either with the applicable covered project requirements for the respective residential and commercial portions of the project or may propose to utilize a mixed-use rating system, subject to approval by the chief building official.

Table 2: Energy and Electrification Menu of Measures by Climate Zone Measure
Climate Zone Steps
2 1) Choose your Climate
Zone using CEC toolfinder1
Specification
Spec. ID
(Refer to
Table 3)
Target Score 2) Minimum Target Score
needed to comply
(1 point = 1MMBTU savings
per yr.)
9 Lighting E1 Mandatory 3) Choose a measure or a
combination of measures
that adds up to the
minimum target score
above based on CZ.

Measures listed as
“Mandatory” MUST be
installed.
4) Use the Specification
Number (Spec. ID) column
as a key and conform to the
specifications in Table 3
below. Table 3 describes,
specifies, and details
compliance with each
corresponding measure.

Water Heating
Package E2 2
Air Sealing E3 1
R-49 Attic
Insulation E4.B 2
Duct Sealing E5 3
New Ducts, R8 Insulation +
Duct Sealing
E6.B 6
Windows E7 3
R-19 Raised
floor
insulation
E10.A 8
Radiant
Barrier Under
Roof
E12 1
HPWH
Replacing
Gas
FS1 12
High Eff
HPWH
Replacing
Gas
FS2 13
HPWH
Replacing
Electric
FS3 4
High Eff
HPWH
Replacing
Electric
FS4 5
HVAC Heat
Pump FS5 17
High
Efficiency FS6 19

HVAC Heat
Pump
Heat Pump
Clothes Dryer FS8 1
Induction
Cooktop FS9 1
Solar PV PV.A 14
1California Energy Commission climate zone tool finder at https://www.energy.ca.gov/programs-andtopics/programs/building-energy-efficiency-standards/climate-zone-tool-maps-and.

The following conditions also apply to Table 2:
(a) Unless otherwise specified, the requirements shall apply to the entire dwelling unit, not just the additional or altered portion.
(b) Measures from the Measure Menu in Table 2 and specified in Table 3, that already exist in the home, may be counted towards compliance with these requirements, unless otherwise specified in Table 3.
(c) Measures from the Measure Menu in Table 2 that are to be installed to satisfy requirements under the State Energy Code, Title 24, Part 6, may also be counted towards compliance with these requirements. Where these requirements conflict with other Energy Code requirements, the stricter requirements shall prevail.

Table 3: Energy Efficiency Measures
ID Measure Specification
Energy
Measurer
s
E1 Lighting Measures – Install lighting with an efficiency of 45 lumens per watt or greater in all interior and exterior screw-in fixtures. Install photocell, occupancy sensor or energy management system controls that meet the requirements of 150.0(k)3 in all outdoor lighting permanently mounted to a residential building or to other buildings on the same lot.

E2 Water Heating Package: Insulate all accessible hot water pipes with pipe insulation a minimum of ¾ inch thick. This includes insulating the supply pipe leaving the water heater, piping to faucets underneath sinks, and accessible pipes in attic spaces or crawlspaces. Upgrade fittings in sinks and showers to meet current California Green Building Standards Code (Title 24, Part 11) Section 4.303 water efficiency requirements.

Exception: Upgraded fixtures are not required if existing fixtures have rated or measured flow rates of no more than ten percent greater than 2025 California Green Building Standards Code (Title 24, Part 11) Section 4.303 water efficiency requirements.

E3 Air Sealing: Seal all accessible cracks, holes, and gaps in the building envelope at walls, floors, and ceilings. Pay special attention to penetrations including plumbing, electrical, and mechanical vents, recessed can light luminaires, and windows. Weather-strip doors if not already present. Verification shall be conducted following a prescriptive checklist that outlines which building aspects need to be addressed by the permit applicant and verified by an inspector. Compliance can also be demonstrated with blower door testing conducted by a certified ECC Rater no more than three years prior to the permit application date that either:
a) shows at least a 30 percent reduction from pre-retrofit conditions; or b) shows that the number of air changes per hour at 50 Pascals pressure difference (ACH50) does not exceed ten for Pre-1978 vintage buildings, seven for 1978 to 1991 vintage buildings and five for 1992- 2010 vintage buildings. If combustion appliances are located within the pressure boundary of the building, conduct a combustion safety test by a certified ECC Rater or a professional certified by the Building Performance Institute, in accordance with the BPI Technical Standards for the Building Analyst Professional.

E4.B R-49 Attic Insulation: Attic insulation shall be installed to achieve a weighted assembly U-factor of 0.020 or insulation installed at the ceiling level shall have a thermal resistance of R-49 or greater for the insulation alone. Recessed downlight luminaires in the ceiling shall be covered with insulation to the same depth as the rest of the ceiling. Luminaires not rated for insulation contact must be replaced or fitted with a fire-proof cover that allows for insulation to be installed directly over the cover. Exception: In buildings where existing R-30 is present and existing recessed downlight luminaires are not rated for insulation contact, insulation is not required to be installed over the luminaires.

E5 Duct Sealing: Air seal all space conditioning ductwork to meet the requirements of the 2025 Title 24, Part 6, Section 150.2(b)1E. The duct system must be tested by a ECC Rater no more than three years prior to the Covered Single Family Project permit application date to verify the duct sealing and confirm that the requirements have been met. This measure may not be combined with the New Ducts and Duct Sealing measure in this Table.

Exception: Buildings without ductwork or where the ducts are in conditioned space.

E6.B New Ducts, R-8 insulation + Duct Sealing: Replace existing space conditioning ductwork with new R-8 ducts that meet the requirements of 2025 Title 24, Part 6, Section 150.0(m)11. This

measure may not be combined with the Duct Sealing measure in this Table. To qualify, a preexisting measure must have been installed no more than three years before the Covered Single Family Project permit application date.

E7 Windows: Replace at least 50% of existing windows with high performance windows with an area-weighted average U-factor no greater than [0.27 in Climate Zones 2] E8 R-15 Wall Insulation: Install wall insulation in all exterior walls to achieve a weighted U-factor of 0.095 or install wall insulation in all exterior wall cavities that shall result in an installed thermal resistance of R-15 or greater for the insulation alone.

E9 Reserved for future use
E10.A R-19 Floor Insulation: Raised-floors shall be insulated such that the floor assembly has an assembly U-factor equal to or less than U-0.037 or shall be insulated between wood framing with insulation having an R-value equal to or greater than R-19.

E12 Radiant Barrier: A radiant barrier that meets the requirements of Section 150.1(c)2 shall be installed under at least 50% of the roof surface.

Fuel Substitution and Solar PV Measures
FS1 Heat Pump Water Heater (HPWH) Replacing Gas: Replace existing natural gas water heater with a heat pump water heater that meets the requirements of Sections 110.3 and 150.2(b)1.H.iii.b.

FS2 High Efficiency Heat Pump Water Heater (HPWH) Replacing Gas: Replace existing natural gas water heater with heat pump water heater with a Northwest Energy Efficiency Alliance (NEEA) Tier 3 or higher rating that also meets the requirements of Sections 110.3 and 150.2(b)1.H.iii.c.

FS3 Heat Pump Water Heater (HPWH) Replacing Electric: Replace existing electric resistance water heater with a heat pump water heater that meets the requirements of Sections 110.3 and 150.2(b)1.H.iii.b.

FS4 High Efficiency Heat Pump Water Heater (HPWH) Replacing Electric: Replace existing electric resistance water heater with heat pump water heater with a Northwest Energy Efficiency Alliance (NEEA) Tier 3 or higher rating that also meets the requirements of Sections 110.3, and 150.2(b)1.H.iii.c.

FS5 Heat Pump Space Conditioning System: Replace all existing gas and electric resistance primary space heating systems with a heat pump system that meets the requirements of Sections 110.3, 150.2(b)1.C, 150.2(b)1.E, 150.2(b)1.F, and 150.2(b)1.G.

FS6 High Efficiency Heat Pump Space Conditioning System: Replace all existing gas and electric resistance primary space heating systems with an electric-only heat pump system that meets the requirements of Sections 110.3 and 150.2(b)1.C, 150.2(b)1.E, 150.2(b)1.F, and 150.2(b)1.G and one of the following:

A. A ducted heat pump system with a SEER2 rating of 16.5 or greater, an EER2 rating of

12.48 or greater and an HSPF2 rating of 9.5 or greater; or B. A ductless mini-split heat pump system with a SEER2 rating of 14.3 or greater, an EER2 rating of 11.7 or greater and an HSPF2 rating of 7.5 or greater FS7 Dual Fuel Heat Pump Space Conditioning System: Install a heat pump space conditioning system that meets the requirements of Sections 110.3 and 150.2(b)1.C, 150.2(b)1.E, 150.2(b)1.F, and 150.2(b)1.G and either:

A. Replaces all existing gas and electric resistance primary heating systems with a hybrid gas and electric heat pump system, or
B. Is an electric-heat pump system in tandem with a gas furnace and controls to use the gas furnace for backup heat only.

FS8 Heat Pump Clothes Dryer: Replace existing electric resistance or gas clothes dryer with heat pump dryer with no resistance element and cap gas line.

FS9 Induction Cooktop: Replace all existing gas and electric resistance stove tops with induction stove top and cap the gas line.

PV.A Solar PV: Install a solar PV system that meets the requirements of Section 150.1(c)14.

15.04.090 Incentives for compliance
In addition to the required standards for compliance, the Town Council may establish by resolution, financial or application processing incentives and/or award or recognition programs to encourage higher levels of green building compliance for a project.

15.04.095 Administrative procedures.

The procedures for compliance with the provisions of this chapter shall include, but not be limited to the following:
(a) Project design. Applicants for a covered project are strongly encouraged to involve a qualified green building rater in the initial design phases of the project in advance of submittal of an application to determine applicable green building compliance thresholds and the most cost effective and appropriate means of achieving compliance.
(b) Planning applications. If a discretionary planning application is required for a covered project, applicants should be prepared to identify expected green building measures to be included in the project to achieve the compliance thresholds. Applicants should identify any anticipated difficulties in achieving compliance and any exemptions from the requirements of this chapter that may be requested. (c) Building plan check review. Upon submittal of an application for a building permit, building plans for any covered project shall include a green building program description and completed checklist. The checklist shall be incorporated onto a separate full-sized plan sheet included with the building plans. Evidence that the project, as indicated by the project plans and green building program description, will achieve the standards for compliance outlined in Section 15.04.085, shall be provided prior to issuance of a building permit.
(d) Changes during construction. During the construction process, alternate green building measures may be substituted, provided that documentation of the proposed change and the project's continued ability to achieve the standards for compliance to the chief building official shall be provided.
(e) Final building inspection. Prior to final building inspection and occupancy for any covered project, evidence that project construction has achieved the required compliance set forth in the standards for compliance outlined in Section 15.04.085 shall be provided. The chief building official shall review the documentation submitted by the applicant and determine whether the project has achieved the compliance threshold as set forth in the standards for compliance outlined in Section 15.04.085. If the chief building official determines that the applicant has met these requirements, the final building inspection may proceed.
(f) Conflict with other laws. The provisions of this chapter are intended to be in addition to and not in conflict with other laws, regulations and ordinances relating to building construction and site development. If any provision of this chapter conflicts with any duly adopted and valid statutes or regulations of the federal government or the state of California, the federal or state statutes or regulations shall take precedence.

15.04.100 Exemptions.
(a) The provisions of this chapter shall not apply to:
(1) Buildings which are temporary (such as construction trailers). (2) Building area which is not or is not intended to be conditioned space. (3) Any requirements of this chapter which would impair the historic integrity of any building listed on a local, state or federal register of historic structures, as determined by the chief building official and as regulated by the California Historic Building Code (Title 24, Part 8). In making such a determination, the chief building official may require the submittal of an evaluation by an architectural historian or similar expert.
(b) As outlined in the 2025 CALGreen code, sections 4.106.4 and 5.106.5, applicants may be exempted from the electric vehicle changing requirements on a case-by-case basis where the local enforcing agency has determined EV charging and infrastructure are not feasible based upon one or more of the following conditions:
(1) Where there is no local utility power supply or the local utility is unable to supply adequate power.
(2) Where there is evidence suitable to the local enforcing agency substantiating that additional local utility infrastructure design requirements, directly related to the implementation of sections 4.106.4 and 5.106.5 may adversely impact the construction cost of the project.
(3) ADUs and JADUs without additional parking facilities. (4) Areas of parking facilities served by parking lifts, including but not limited to, automated mechanical-access open parking garages as defined in the California Building Code; or parking facilities otherwise of supporting electric vehicle charging.
(c) Hardship or infeasibility exemption. If an applicant for a covered project believes that circumstances exist that make it a hardship or infeasible to meet the requirements of this chapter, the applicant may request an exemption as set forth below. In applying for an exemption, the burden is on the applicant to show hardship or infeasibility. (1) Application. Based on the following, the applicant shall identify in writing the specific requirements of the standards for compliance that the project is unable to achieve and the circumstances that make it a hardship or infeasible for the project to comply with this chapter. The applicant may not petition for relief from any requirement of the 2025 California Energy Code (Title 24, Part 6) and referenced standards, or the 2025 California Green Building Standards (Title 24, Part 11) of the California Building Standards Code. Circumstances that constitute hardship or infeasibility shall include one of the following:
a. That the cost of achieving compliance is disproportionate to the overall cost of the project;
b. That strict compliance with these standards would create or maintain a hazardous condition(s) and present a life safety risk to the occupants; c. There is a conflict between the provisions of the applicable green building rating system and the California Building Standards Code, other state code

provisions, other requirements of this title or conditions imposed on the project through a previously approved planning application; d. That compliance with certain requirements would impair the historic integrity of buildings listed on a local, state or federal list or register of historic structures as regulated by the California Historic Building Code (Title 24, Part 8).
(2) Granting of exemption. If the chief building official determines that it is a hardship or infeasible for the applicant to fully meet the requirements of this chapter and that granting the requested exemption will not cause the building to fail to comply with the 2025 California Energy Code (Title 24, Part 6) and referenced standards, or the 2025 California Green Building Standards (Title 24, Part 11) of the California Building Standards Code, the chief building official shall determine the maximum feasible threshold of compliance reasonably achievable for the project.

In making this determination, the chief building official shall consider whether alternate, practical means of achieving the objectives of this chapter can be satisfied, such as reducing comparable energy use at an off-site location within the county. If an exemption is granted, the applicant shall be required to comply with this chapter in all other respects and shall be required to achieve the threshold of compliance determined to be achievable by the chief building official. (3) Denial of exception. If the chief building official determines that it is reasonably possible for the applicant to fully meet the requirements of this chapter, the request shall be denied, and the applicant shall be notified of the decision in writing. The project and compliance documentation shall be modified to comply with the standards for compliance.
(4) Appeal. Any aggrieved applicant or person may appeal the determination of the chief building official regarding the granting or denial of an exemption or compliance with any other provision of this chapter. An appeal of a determination of the chief building official shall be filed in writing and processed in accordance with the provisions of Section 15.04.028 of this code.” SECTION 3. CEQA.

This Ordinance was assessed in accordance with the authority and criteria contained in the California Environmental Quality Act (CEQA), the State CEQA Guidelines, and the environmental regulations of the Town. The Town Council finds and determines that the adoption of this Ordinance is exempt from CEQA in accordance with Sections 15307 and 15308 because this Ordinance constitutes action by a regulatory agency to protect natural resources and the environment. The Ordinance will establish regulations to further energy efficiencies and efficient use of natural resources to reduce adverse impacts to the environment, consistent with the Town Council’s adopted Climate Action Plan. Pursuant to the “common sense” exemption under CEQA Guidelines section 15061(b)(3), there is no possibility that this Ordinance might have a significant adverse effect on the environment. The Ordinance establishes regulations to minimize and/or avoid impacts to the environment and to protect the health, welfare, and safety of the Town’s citizenry. The Town has further determined that no exceptions to the exemptions apply and there is no reasonable possibility that the activity will have a significant adverse effect on the environment due to unusual circumstances (CEQA Guidelines section 15300.2). At the time of future development proposals, additional environmental analysis may be required to analyze the potential environmental impacts associated with specific development projects and uses proposed at specific locations.

SECTION 4. Validity & Severability.

A. Except as specifically provided herein, nothing contained in this Ordinance shall be deemed to modify or supersede any prior enactment of the Town Council which addresses the same subject addressed herein.

B. If any section, subsection, sentence, clause, or phrase of this Ordinance is for any reason held to be invalid by a court of competent jurisdiction, such decision shall not affect the validity of the remaining portion of this Ordinance. The Town Council of the Town of Fairfax hereby declares that it would have adopted the ordinance and each section, subsection, sentence, clause, or phrase thereof, irrespective of the fact that any one or more sections, subsections, sentences, clauses or phrases shall be declared invalid.

SECTION 5. Ordinance Publication and Effective Date.

A. Within fifteen (15) days after its adoption, this Ordinance shall be posted in at least three public places in the Town of Fairfax as provided in Government Code 36933 and a certified copy of the full text of this Ordinance shall be posted in Town Hall.

B. This Ordinance shall take effect January 1, 2026.

C. The Town Clerk shall cause Section 2 of this Ordinance to be codified in the Fairfax Municipal Code.

D. This Ordinance, together with the findings in Exhibit A, shall be filed with the California Building Standards Commission within thirty (30) days after its final passage.

THE FOREGOING ORDINANCE was first read at a regular meeting of the Fairfax Town Council on October 15, 2025 and was passed and adopted at a regular meeting of the Town Council on November 5, 2025 , by the following vote, to wit:

AYES:

NOES:

ABSENT:
_________________________________
Mayor
Attest:
______________________________
Town Clerk

EXHIBIT “A”
FINDINGS OF FACT IN SUPPORT OF ORDINANCE NO. 872 ENTITLED “AN ORDINANCE OF THE TOWN OF FAIRFAX AMENDING CHAPTER 15.04 OF THE FAIRFAX TOWN CODE AND ADOPTING BY REFERENCE THE 2025 CALIFORNIA BUILDING STANDARDS CODE, INCLUDING THE 2025 CALIFORNIA ADMINISTRATIVE CODE, THE 2025 CALIFORNIA BUILDING CODE, THE 2025 CALIFORNIA RESIDENTIAL CODE, THE 2025 CALIFORNIA ELECTRICAL CODE, THE 2025 CALIFORNIA MECHANICAL CODE, THE 2025 CALIFORNIA PLUMBING CODE, THE 2025 CALIFORNIA ENERGY CODE, THE 2025 CALIFORNIA HISTORICAL BUILDING CODE, THE 2025 CALIFORNIA EXISTING BUILDING CODE, THE 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE, AND THE 2025 CALIFORNIA REFERENCED STANDARDS CODES, WITH LOCAL AMENDMENTS, AND THE 2024

EDITION OF THE INTERNATIONAL PROPERTY MAINTENANCE CODE
Pursuant to Sections 17958.5 and 17958.7(a) of the State of California Health and Safety Code, the Town Council of the Town of Fairfax has determined and finds that all the changes or modifications in this ordinance to the California Building Standards Code (California Code of Regulations, Title 24) are necessary because of the following local climatic, geological, and/or topographic conditions:

1. CLIMATIC:
a. Precipitation. The normal year’s rainfall is approximately 30 to 50 inches on the average calendar year. The area has been subject to extended periods of drought and less than normal rainfall as well as intense rains, which have caused local flooding and damage from geotechnical failure (landslides). Approximately ninety percent (90%) of the annual rainfall is experienced during the months of November through April, and 10% from May through October. b. Relative Humidity. Moisture in the air, also known as relative humidity, changes significantly during any given day. Humidity generally ranges from 50% during daytime hours to 85% at night. It drops to 30% during the summer months and occasionally drops lower. During periods when the area experiences easterly hot, dry winds, the relative humidity drops significantly, thus creating a greater danger.
c. Temperatures. Average summer highs are in the 75 degree to 85 degree range.

There are weather periods where temperatures can rapidly reach 100 degrees and have been recorded even higher.
d. Winds. Prevailing winds are generally from the West. However, winds are experienced from virtually every direction at one time or another, due to topography. Velocities are generally in the 5 – 15 mph range, gusting to 10 – 30 mph, particularly during the summer months.

Extreme winds, up to 50 mph, have been known to occur.
e. Summary. The climate (weather patterns) within the Town of Fairfax is predominantly affected by the marine influence of the Pacific Ocean. During the summer months, the southerly exposed slopes and open fields become dry with seasonal grasses, which present a fuel for the rapid spread of fire. The Northerly slopes are heavily wooded and present a moderate to heavy fuel load with respect to fire danger. These local climactic conditions affect the acceleration, intensity, and size of fire in the community. Times of little or no rainfall, of low humidity and high temperatures create extremely hazardous conditions. Furthermore, winds experienced in this area can have a tremendous

impact upon structure fires of buildings in close proximity to one another and wildland areas. All water storage and supply comes from reservoirs and lakes within the county, and are affected by the climate accordingly.

2. GEOGRAPHICAL and TOPOGRAPHICAL:
a. Geographical Features. The geographical features in and around the Town of Fairfax are a source of enjoyment for our residents. The hills and valleys give a natural beauty to the area with forested hills and golden yellow meadows leading up to them. These geographic features form the backdrop for the residential and commercial communities and dictate the locations of roadways and building locations. These geographic features also create barriers, which negatively affect accessibility and influence fire behavior during major conflagrations. Many structures (new and old) are constructed of highly combustible material, which offer little resistance to fire and could contribute to the spread of fire. For practical and cost reasons, new structures are built of wood (type V) construction. The potential for conflagration exists with the density of the various specific areas of the Town. The concentrated commercial, as well as residential occupancies, causes concern when considering the “exposure” elements of building to building to grass and brush areas of the Town. b. Seismic Location. The Town of Fairfax lies within the recognized seismic zone #4, which is the most dangerous zone. While the area has experienced several significant seismic events, there has been a minimum of damage. The Town sits between two active earthquake faults (San Andreas and Hayward) and numerous potentially active faults. The potential for great damage exists, and must be considered as a real threat to be planned for. c. Size and Population. The Town of Fairfax encompasses an area of 2.2 miles with a resident population of approximately 7,500. The Town is served by the Ross Valley Fire Authority.

Ross Valley Fire has four (4) stations (two of which are in San Anselmo, one in Fairfax, and one in Ross), 34 fire personnel (serving the Town of Fairfax, San Anselmo, Ross and the Sleepy Hollow Fire Protection District), with diverse responsibilities including wildland, urban, and paramedical. d. Roads and Streets. Several of the heavily populated areas have limited roadways and escape routes. The Town of Fairfax has numerous narrow, winding roads, some barely passable with modern fire apparatus, causes access problems and extended travel times especially in the older hillside sections of the jurisdiction. The accessibility for fire department apparatus is of concern due to the lack of turnouts and roadway widths which increases response time. e. Topography. The Department’s service area is a conglomeration of oak plains, hills, valleys and ridges. The flatter lands are found in the center portion of the service area and approximately half of the residential development is in this area. The other half of the service area with residential development consists of hillsides with slopes ranging from approximately 15-30% and 30+%. These hazardous conditions present an exceptional and continuing fire danger to the residents of the community due to the difficulty of the terrain and topography of the area, much of it consisting of boxed canyons with steep, brush covered slopes; narrow winding streets used by residents of the area and the Fire Department for ingress and egress, steep hills which hinder Fire Department response time; older and inadequate water systems in certain areas of the community; and the location of buildings and structures with relation to these dangerous areas. The water supply for domestic and fire flow systems within this Town are directly affected by the topographical layout of the Town. The supply of water comes from lakes, which are managed by a public utilities district responsible for maintaining an adequate supply. The water distribution system within the Town is very old in some areas served by mains, which are inadequate in size to provide water for fire protection. The valley floor is served by mains which contain an exceptionally large volume of water for fire protection. The

Town of Fairfax has a base elevation of approximately 120 feet and extends to areas in excess of 900 feet above sea level.
f. Vegetation. The Town Council recognizes that the Town of Fairfax has within its borders and along its boundaries, significant areas of grass, brush and heavily forested lands. In addition, the natural vegetation of the area has been altered by the addition of ornamental trees and shrubs, which are not native and add fuel around the houses and buildings of our community. The south facing exposure is primarily annual grasses, highly flammable brush, with occasional clumps of bay and oak trees in the more sheltered pockets. The north facing slopes are heavily wooded from lower elevations to ridge with oak and bay trees and minor shrubs of the general chaparral class.

Expansion of the residential community into areas of heavier vegetation has resulted in homes existing in close proximity to dense natural foliage. Often such dwellings are completely surrounded by highly combustible vegetation compounding the fire problem from a conflagration point of view. Of particular recent notice is the increase in dead down fuel and ladder accumulation directly associated with the sudden oak death syndrome.
g. Summary. The above local geographic and topographic conditions increase the magnitude, exposure, accessibility problems and fire hazards presented to the Fire Department.

Fire following an earthquake has the potential of causing greater loss of life and damage than the earthquake itself.

The valley floor has zones recognized by the Federal Emergency Management Agency as flood zones. During times of intense rainfall, flooding and landslides have occurred which have destroyed structures and threatened lives. Within the past decade, these events have caused the local government to declare disasters and seek state and federal assistance.

Some of the existing structures in the commercial areas of the Town lack the required firewall separation. These structures cause concern to the Fire Department because of the potential for major conflagration. As these structures are replaced, the exposure potential will be significantly reduced.

Several other variables may tend to intensify an incident, such as, the extent of damage to the water system; the extent of roadway damage and/or amount of debris blocking the roadways; climatic conditions (hot, dry weather with high winds); time of day will influence the amount of traffic on roadways and could intensify the risk to life during normal business hours; and the availability of timely mutual aid or military assistance.

3. AB 130 EXCEPTIONS
a. Substantially Equivalent: The Town’s proposed amendments are substantially equivalent under AB 130, as they continue adoption of Tier 1 and the Flex Compliance Pathway previously approved and filed with the California Building Standards Commission before September 30, 2025.

The updates align the Tier 1 framework with the 2025 CALGreen Code and revise FlexPath measures based on the State’s most recent cost-effectiveness guidance. These changes maintain the same intent and performance outcomes as the existing standards and do not introduce new or more stringent local requirements.

Conclusion: The Town Council of the Town of Fairfax hereby finds and determines that as a result of these conditions and the resulting health and safety hazards, the changes and modifications to the California Administrative, Building, Residential, Electrical, Mechanical, Plumbing, Energy, Historical Building, Existing Building, Green Building Standards, and Referenced Standards

Codes, thereto enacted by Chapter 15.04 of the Town Code are reasonably necessary as listed in the table below:

Chapter 15.04 Amendments to the California Building Code Town Code CBC Section Substance of Amendment Findings
Section Added or Amended (full text in Ordinance No. 872)

15.04.015 202 Add definition of “Substantial Remodel” and “Second Unit.”
Admin
903.2 Automatic Sprinkler Systems in New
Buildings—Where Required
1a, 1b, 1c,
1d, 1e, 2a,
2c, 2d, 2e,
2f, 2g
903.3 Add language regarding continued
allowance of provisions for area and height
increase, or Fire-Resistive substitution
otherwise allowed by Building Code
sections 504 and 506; requirement that
attached garages and attics be sprinkled
1a, 1b, 1c,
1d, 1e, 2a,
2c, 2d, 2e,
2f, 2g
906.11 Fire Extinguisher Documentation 1a, 1b, 1c,
1d, 1e, 2a,
2c, 2d, 2e,
2f, 2g
907.2 Add paragraphs relating to “New
Construction” and “Existing Construction”
1a, 1b, 1c,
1d, 1e, 2a,
2c, 2d, 2e,
2f, 2g
907.8.1 Smoke Alarm Documentation 2a, 2b, 2c,
2d, 2e, 2g

15.04.025 109.2 Requirement for plan review fee to be paid at time of document submittal
Admin

15.04.030 1505.1 Roof coverings, add language requiring Class A Roof Assembly
1a, 1b, 1c,
1d, 1e, 2a,
2c, 2d, 2e,
2f, 2g

15.04.045 109.7 Reinstatement of expired permits lacking only final inspection for a fee
Admin

15.04.055 1511.9.2 Alternative Power Supplies for photovoltaic panels to comply with CBSC requirements
1a, 1b, 1c,
1d, 1e, 2a,
2c, 2d, 2e,
2f 2g

Chapter 15.04 Amendments to the California Residential Code Chapter 15.04 Amendments to the 2025 California Wildland-Urban Interface Code Town Code WUI Section Substance of Amendment Findings
Section Added or
Amended
(full text in Ordinance No. )

15.04.015 R202 Add definition of “Substantial Remodel”
and “Second Unit.”
Admin

15.04.020 501.1 Scope Admin
501.1.1 Application Admin,
1a, 1b, 1c,
1d, 1e, 2a,
2c, 2d, 2e,
2f, 2g
Town Code CRC Section Substance of Amendment Findings
Section Added or Amended (full text in Ordinance No. 872)

15.04.015 R202 Add definition of “Substantial Remodel” and “Second Unit.”
Admin
R313.1/R313.2 Approved Automatic Sprinkler Systems in
New Buildings—Where Required
1a, 1b, 1c,
1d, 1e, 2a,
2c, 2d, 2e,
2f, 2g
R313.1.1/R313.2.1 Add language regarding continued
allowance of provisions for area and height
increase, or Fire-Resistive substitution
otherwise allowed by Building Code
sections 504 and 506; requirement that
attached garages and attics be sprinkled
1a, 1b, 1c,
1d, 1e, 2a,
2c, 2d, 2e,
2f, 2g

15.04.030 R902.1 Roof coverings, add language requiring Class A Roof Assembly
1a, 1b, 1c,
1d, 1e, 2a,
2c, 2d, 2e,
2f, 2g

15.04.035 Appendix CI Swimming Pool Safety Act, to the extent it does not conflict with CBC
2c, 2d

15.04.045 R108.7 Reinstatement of expired permits lacking only final inspection for a fee
Admin

15.04.055 R324.7.4 Alternative Power Supplies for photovoltaic panels to comply with CBSC requirements
1a, 1b, 1c,
1d, 1e, 2a,
2c, 2d, 2e,
2f, 2g

504.5.3 Requirement for compliant coverings
when more than 50% of exterior wall
coverings are repaired or replaced
within 36 months
1a, 1b, 1c,
1d, 1e, 2a,
2c, 2d, 2e,
2f, 2g

Chapter 15.04 Plumbing Code
Chapter 15.04 International Building Code
Town Code CPC Section Substance of Amendment Findings
Section Added or Amended (full text in Ordinance No.)

15.04.040 713.1 Requirement to have connection to public sewer, exception for existing septic tank
systems
1a, 1b
Town Code IBC Section Substance of Amendment Findings
Section Added or Amended (full text in Ordinance No.

15.04.035 3109 Swimming Pool Safety Act, to the extent it does not conflict with CBC
2c, 2d

Chapter 15.04 Energy Code
Town Code CENC Section Substance of Amendment Findings
Section Added or Amended (full text in Ordinance No. 872)

15.04.070 100.0 Single-Family Building Remodel Energy
Reach Code
Admin
100.1(b) Add definitions for “All-Electric Building,”
“All-Electric Design,” “Covered Projects,”
and “Mixed-Fuel”
Admin
150 Single-Family Residential Buildings –
Mandatory Features and Devices
Admin
150.0(w) Requirements for a Covered Project Admin

Chapter 15.04 CALGreen Code
Town Code CALGreen Section Substance of Amendment Findings Section Added or Amended (full text in Ordinance No. 872)

15.04.080 301.1 Scope Admin

15.04.085 Table 1, 2 and 3 Standards for Compliance 3a
Prepared by:

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

Kelly Cunningham, Codes and Standards Program, Pacific Gas and Electric Last modified: 2024/04/25
Revision: 1.0
$77$&+0(17%
Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Executive Summary
2 Legal Notice
This report was prepared by Pacific Gas and Electric Company and funded by the California utility customers under the auspices of the California Public Utilities Commission.

Copyright 2024, Pacific Gas and Electric Company. All rights reserved, except that this document may be used, copied, and distributed without modification.

Neither PG&E nor any of its employees makes any warranty, express or implied; or assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any data, information, method, product, policy or process disclosed in this document; or represents that its use will not infringe any privately-owned rights including, but not limited to, patents, trademarks or copyrights.

Acronym List
2023 PV$ – Present value costs in 2023
ACH50 – Air Changes per Hour at 50 pascals pressure differential ACM – Alternative Calculation Method
ADU – Accessory Dwelling Unit
AFUE – Annual Fuel Utilization Efficiency
B/C – Lifecycle Benefit-to-Cost Ratio
BEopt – Building Energy Optimization Tool
BSC – Building Standards Commission
CA IOUs – California Investor-Owned Utilities
CASE – Codes and Standards Enhancement
CBECC-Res – Computer program developed by the California Energy Commission for use in demonstrating compliance with the California Residential Building Energy Efficiency Standards CEER – Combined Energy Efficiency Rating
CFI – California Flexible Installation
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
DWHR – Drain Water Heat Recovery
EDR – Energy Design Rating
EER – Energy Efficiency Ratio
EF – Energy Factor
Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Executive Summary
3 GHG – Greenhouse Gas
HERS Rater – Home Energy Rating System Rater
HPA – High Performance Attic
HPSH – Heat Pump Space Heater
HPWH – Heat Pump Water Heater
HSPF – Heating Seasonal Performance Factor
HVAC – Heating, Ventilation, and Air Conditioning
IECC – International Energy Conservation Code
IOU – Investor Owned Utility
kBtu –British thermal unit (x1000)
kWh – Kilowatt Hour
LBNL – Lawrence Berkeley National Laboratory
LCC – Life Cycle Cost
LLAHU – Low Leakage Air Handler Unit
VLLDCS – Verified Low Leakage Ducts in Conditioned Space LSC – Long-term Systemwide Cost
MF – Multifamily
MSHP – Mini-Split Heat Pump
NEEA – Northwest Energy Efficiency Alliance
NEM – Net Energy Metering
NPV – Net Present Value
NREL – National Renewable Energy Laboratory
PG&E – Pacific Gas and Electric Company
POU – Publicly-Owned-Utilities
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
VCHP – Variable Capacity Heat Pump, Title 24 compliance credit ZNE – Zero-net Energy
Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Executive Summary
4 Summary of Revisions
Date Description Reference (page or section)
4/25/2024 Original Release N/A
Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Executive Summary
5 TABLE OF CONTENTS
Executive Summary..........................................................................................................................................................1 1 Introduction................................................................................................................................................................6 2 Methodology and Assumptions...............................................................................................................................7

2.1 Analysis for Reach Codes..................................................................................................................................................... 7

2.1.1 Modeling ....................................................................................................................................................................... 7

2.1.2 Prototype Characteristics.............................................................................................................................................. 7

2.1.3 Cost-Effectiveness Approach...................................................................................................................................... 10

2.1.4 Utility Rates................................................................................................................................................................. 11

2.1.5 Measure Cost Data Collection Approach .................................................................................................................... 12

2.2 Measure Details and Cost................................................................................................................................................... 12

2.2.1 Building Envelope & Duct Measures........................................................................................................................... 13

2.2.2 PV Measures .............................................................................................................................................................. 14

2.2.3 Equipment Fuel Substitution Measures – Heat Pump Equipment............................................................................... 15 3 Results......................................................................................................................................................................21

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

3.1.1 HPSH Measures ......................................................................................................................................................... 22

3.1.2 HPWH Measures ........................................................................................................................................................ 24

3.2 Climate Zone Case Studies ................................................................................................................................................ 26

3.2.1 HPSH Cost-Effectiveness ........................................................................................................................................... 26

3.2.2 HPWH Cost-Effectiveness .......................................................................................................................................... 27

3.2.3 Envelope & Duct Improvement Cost-Effectiveness..................................................................................................... 28

3.2.4 Sensitivities................................................................................................................................................................. 29

3.3 Gas Pathways for Heat Pump Replacements..................................................................................................................... 30 4 Recommendations and Discussion.......................................................................................................................32 5 References ...............................................................................................................................................................36 6 Appendices ..............................................................................................................................................................37

6.1 Map of California Climate Zones......................................................................................................................................... 37

6.2 Utility Rate Schedules......................................................................................................................................................... 38

6.2.1 Pacific Gas & Electric.................................................................................................................................................. 39

6.2.2 Southern California Edison ......................................................................................................................................... 47

6.2.3 Southern California Gas.............................................................................................................................................. 51

6.2.4 San Diego Gas & Electric............................................................................................................................................ 53

6.2.5 City of Palo Alto Utilities.............................................................................................................................................. 63

6.2.6 Sacramento Municipal Utilities District (Electric Only)................................................................................................. 65

6.2.7 Fuel Escalation Assumptions...................................................................................................................................... 67 Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Executive Summary
6 LIST OF TABLES
Table 1. Prototype Characteristics........................................................................................................................................................ 8 Table 2. Efficiency Characteristics for Three Vintage Cases ................................................................................................................ 9 Table 3. Measure Cost Assumptions – Efficiency & Duct Measures .................................................................................................. 14 Table 4. Measure Descriptions & Cost Assumptions – PV ................................................................................................................. 15 Table 5. Lifetime Analysis Replacement Assumptions for DFHP (Existing Furnace) Scenario .......................................................... 16 Table 6. System Sizing by Climate Zone ............................................................................................................................................ 17 Table 7. Ducted HVAC Measure Cost Assumptions – 4-Ton Electric Replacements......................................................................... 18 Table 8. Non-Ducted HVAC Measure Cost Assumptions – 4-Ton Electric Replacements ................................................................. 18 Table 9. Water Heating Measure Cost Assumptions – Existing Gas .................................................................................................. 19 Table 10. Water Heating Measure Cost Assumptions – Existing Electric Resistance ........................................................................ 20 Table 11. HPSH CZ 12 [1992-2010]................................................................................................................................................... 26 Table 12. HPSH CZ 16 [1992-2010]................................................................................................................................................... 26 Table 13. HPWH CZ 12 [1992-2010].................................................................................................................................................. 27 Table 14. HPWH CZ 16 [1992-2010].................................................................................................................................................. 27 Table 15. Envelope and Duct Measures CZ 3 [Pre-1978] .................................................................................................................. 28 Table 16. Envelope and Duct Measures CZ 10 [Pre-1978]................................................................................................................. 28 Table 17. Envelope and Duct Measures CZ 12 [Pre-1978]................................................................................................................. 28 Table 18. Sensitivity Analysis Results for On-Bill NPV Cost-Effectiveness in Climate Zone 12, PG&E.............................................. 29 Table 19. Electric Panel Upgrade Sensitivity for CZ 12 [1992-2010] .................................................................................................. 29 Table 20. PG&E Baseline Territory by Climate Zone.......................................................................................................................... 39 Table 21. PG&E Monthly Gas Rate ($/therm)..................................................................................................................................... 39 Table 22: SCE Baseline Territory by Climate Zone ............................................................................................................................ 47 Table 23. SoCalGas Baseline Territory by Climate Zone ................................................................................................................... 51 Table 24. SoCalGas Monthly Gas Rate ($/therm) .............................................................................................................................. 51 Table 25. SDG&E Baseline Territory by Climate Zone ....................................................................................................................... 53 Table 26. SDG&E Monthly Gas Rate ($/therm) .................................................................................................................................. 53 Table 27. CPAU Monthly Gas Rate ($/therm)..................................................................................................................................... 63 Table 28: Real Utility Rate Escalation Rate Assumptions, CPUC En Banc and 2022 TDV Basis ...................................................... 67 Table 29: Real Utility Rate Escalation Rate Assumptions, 2025 LSC Basis ....................................................................................... 68 Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Executive Summary
7 LIST OF FIGURES
Figure 1: DFHP with Existing Furnace............................................................................................................................................ 22 Figure 2: Standard Efficiency HPSH............................................................................................................................................... 22 Figure 3: High Efficiency HPSH...................................................................................................................................................... 23 Figure 4: Ducted MSHP.................................................................................................................................................................. 23 Figure 5: HPSH + PV...................................................................................................................................................................... 23 Figure 6: 240V Federal Minimum HPWH........................................................................................................................................ 24 Figure 7: 240V Market Standard NEEA HPWH .............................................................................................................................. 24 Figure 8: 120V Market Standard NEEA HPWH .............................................................................................................................. 24 Figure 9: 240V Federal Minimum HPWH + PV............................................................................................................................... 24 Figure 10: R-6 Ducts....................................................................................................................................................................... 25 Figure 11: 10% Duct Leakage ........................................................................................................................................................ 25 Figure 12: R-13 Wall Insulation....................................................................................................................................................... 25 Figure 13: R-49 Attic Insulation....................................................................................................................................................... 25 Figure 14. Heat pump space heater path compared to the air conditioner path. ............................................................................ 31 Figure 15. Heat pump water path compared to gas with solar thermal........................................................................................... 31 Figure 16. Map of California climate zones..................................................................................................................................... 37

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Executive Summary
1 California Energy Codes & Standards | A statewide utility program 2024-04-25 Executive 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 (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.

This report documents cost-effective measure upgrades in existing single family buildings that exceed the minimum state requirements. It evaluates efficiency measures such as adding insulation, replacing windows, and duct upgrades, fuel substitution measures that upgrade space heating and water heating to heat pumps, and solar photovoltaics (PV) across all 16 California climate zones. A 1,665 square foot single family home prototype with an attached garage was evaluated in this study.

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 over a 30-year analysis period. On-Bill cost-effectiveness is a customer-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. Long-term Systemwide Cost (LSC) is the California Energy Commission’s LCC methodology for the 2025 Title 24, Part 6 (Title 24) code cycle (previously referred to as Time Dependent Valuation (TDV)), which 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. This is the methodology used by the Energy Commission in evaluating cost-effectiveness for efficiency measures in Title 24 code development.

The following summarizes key results from the study:

Conclusions and Discussion:

1. Envelope measures. Improving envelope performance is very cost-effective in many older homes. In addition to reducing utility costs, these measures provide many other benefits such as improving occupant comfort and satisfaction and increasing a home’s ability to maintain temperatures during extreme weather events and power outages. Below is a discussion of the results of specific measures. a. Adding attic insulation is cost-effective based on both LSC and On-Bill in many climate zones in homes with no more than R-19 existing attic insulation levels. Increasing attic insulation from R-30 to R-49 was still found to be cost-effective based on at least one metric in the colder and hotter climates of Climate Zone 10 (SDG&E territory only) through 16.
b. Insulating existing uninsulated walls is very cost-effective based on both metrics everywhere except Climate Zones 6 and 7 (in Climate Zone 8 it’s only cost-effective based on LSC). c. Adding R-19 or R-30 floor insulation is cost-effective based on LSC in the older two vintages (Pre-1978 and 1978-1991) in all CZ except CZ 6-10.
d. Replacing old single pane windows with new high-performance windows has a very high cost and is typically not done for energy savings alone. However, energy savings are substantial and justify costeffectiveness of this measure based on at least one metric in Climate Zones 4, 8 through 12 (PG&E territory only), and 13 through 16.
e. At time of roof replacement, a cool roof with an aged solar reflectance of 0.25 was found to be costeffective in Climate Zones 4, 6 through 12 (PG&E territory only), and 13 through 15. When the roof deck is replaced during a roof replacement, adding a radiant barrier is low cost and provides substantial cooling energy savings, and was found to be cost-effective in almost all climate zones and homes.

2. Duct measures: Many older homes have old, leaky duct systems that should be replaced when they reach the end of life, typically 20-30 years. In this case, installing new ducts was found to be cost-effective based on at least one metric (both in most cases) everywhere except mild Climate Zone 7 and Climate Zones 5 and 6 in Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Executive Summary
2 California Energy Codes & Standards | A statewide utility program 2024-04-25 the 1978-1991 vintage. If duct systems still have remaining life they should be sealed and tested to meet 10% leakage or lower; however, duct upgrades alone were only found to be cost-effective for newer homes in Climate Zones 10 (SDG&E territory only), 11, and 13 through 16. Duct upgrades may be able to be coupled with other measures to reduce the cost.

3. Heat pump space heating: HPSHs were found to be LSC cost-effective in many cases. The Dual Fuel Heat Pump (existing furnace) was LSC cost-effective everywhere except Climate Zone 15. The HPSH was LSC cost-effective everywhere except Climate Zones 8 and 15. a. Challenges to On-Bill cost-effectiveness include higher first costs and higher first-year utility costs due to higher electricity tariffs relative to gas tariffs. SMUD and CPAU are two exceptions where first year utility costs are lower for heat pumps than for gas equipment. Table 11 shows the impact of utility rates on cost-effectiveness of HPSH where the standard and high efficiency HPSH and the HPSH + PV measures are cost-effective under SMUD but not PG&E. Even with higher first year utility bills, there were some cases that still proved On-Bill cost-effective including the DFHP with an existing furnace in the central valley and northern coastal PG&E territories, the ducted MSHP in the central valley as well as Climate Zone 14 in SDG&E territory, and the HPSH + PV measure in CZ 3-5 (PGE), 7-11, and 12 (SMUD) – 15.
b. The ductless MSHPs were only found to be cost-effective based on either metric in Climate Zones 1 and 16. Ductless MSHPs have a high incremental cost because it is a more sophisticated system than the base model of a wall furnace with a window AC unit. However, the ductless MSHP would provide greater comfort benefits if properly installed to directly condition all habitable spaces (as is required under the VCHP compliance credit as evaluated in this study) which may be an incentive for a homeowner to upgrade their system.
c. Higher efficiency equipment lowered utility costs in all cases and improved cost-effectiveness in many cases, particularly with a ducted MSHP.

4. Heat pump water heating: All the HPWH measures were LSC cost-effective in all climate zones. Most measures were not On-Bill cost-effective with the exception of the HPWH + PV which was cost-effective OnBill in CPAU, SMUD, and SDG&E territories in addition to Climate Zones 11, 13, 14, and 15. The HPWH measures share many of the same challenges as the HPSH measures to achieving cost-effectiveness including high first costs and utility rates and assumptions. Table 13 shows the impact of utility rates on costeffectiveness where some HPWH measures are cost-effective under SMUD utility rates but are not costeffective anywhere under PG&E rates in Climate Zone 12. a. Various HPWH locations were also explored, however there are some factors outside of costeffectiveness that should also be considered. i. HPWHs in the conditioned space can provide benefits such as free-cooling during the summer, reduced tank losses, and shorter pipe lengths, and in some cases show improved cost-effectiveness over garage located HPWHs. However, there are various design considerations such as noise, comfort concerns, an additional heating load in the winter, and condensate removal. Ducting the inlet and exhaust air resolves comfort concerns but adds costs and complexity. Split heat pump water heaters address these concerns, but currently there are limited products on the market and there is a cost premium relative to the packaged products.
ii. Since HPWHs extract heat from the air and transfer it to water in the storage tank, they must have adequate ventilation to operate properly. Otherwise, the space cools down over time, impacting the HPWH operating efficiency. This is not a problem with garage installations but needs to be considered for water heaters located in interior or exterior closets. For the 2025 Title 24 code the CEC is proposing that all HPWH installations meet mandatory ventilation requirements (California Energy Commission, 2023).

5. The contractor surveys revealed overall higher heat pump costs than what has been found in previous analyses. This could be due to incentive availability raising demand for heat pumps and thereby increasing the price. This price increase may be temporary and may come down once the market stabilizes. There are also Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Executive Summary
3 California Energy Codes & Standards | A statewide utility program 2024-04-25 new initiatives to obtain current costs including the TECH Clean California program1 that publishes heat pump data and costs; however, at the time of this analysis, the TECH data did not contain incremental costs because it only had the heat pump costs but not the gas base case costs.

6. Table 18 shows how CARE rates and escalation rate assumptions will impact cost-effectiveness. a. Applying CARE rates in the IOU territories has the overall impact to increase utility cost savings for an all-electric building compared to a code compliant mixed fuel building, improving On-Bill costeffectiveness. This is due to the CARE discount on electricity being higher than that on gas. The reverse occurs with efficiency measures where lower utility rates reduce savings and subsequently reduce cost-effectiveness.
b. If gas tariffs are assumed to increase substantially over time, in-line with the escalation assumption from the 2025 LSC development, cost-effectiveness substantially improves for the heat pump measures over the 30-year analysis period and many cases become cost-effective that were not found to be cost-effective under the CPUC / 2022 TDV escalation scenario. There is much uncertainty surrounding future tariff structures as well as escalation values. While it’s clear that gas rates will increase, how much and how quickly is not known. Future electricity tariff structures are expected to evolve over time, and the CPUC has an active proceeding to adopt an income-graduated fixed charge that benefits low-income customers and supports electrification measures for all customers.2 The CPUC will make a decision in mid-2024 and the new rates are expected to be in place later that year or in 2025. While the anticipated impact of this rate change is lower volumetric electricity rates, the rate design is not finalized. While lower volumetric electricity rates provide many benefits, it also will make building efficiency measures harder to justify as cost-effective due to lower utility bill cost savings.

7. Under NBT, utility cost savings for PV are substantially less than what they were under prior net energy metering rules (NEM 2.0); however, savings are sufficient to be On-Bill cost-effective in all climate zones except Climate Zones 1 through 3, 5, and 6.
a. Combining a heat pump with PV allows the additional electricity required by the heat pump to be offset by the PV system while also increasing on-site utilization of PV generation rather than exporting the electricity back to the grid at a low rate.
b. While not evaluated in this study, coupling PV with battery systems can be very advantageous under NBT increasing utility cost savings because of improved on-site utilization of PV generation and fewer exports to the grid.

Recommendations:

1. There are various approaches for jurisdictions who are interested in reach codes for existing buildings. Some potential approaches are listed below along with key considerations. a. Prescriptive measures: Non-preempted measures that are found to be cost-effective may be prescriptively required in a reach code. One example of this type or ordinance is a cool roof requirement at time of roof replacement. Another example is requiring specific cost-effective measures for larger remodels, such as high-performance windows when new windows are installed or duct sealing and testing when ducts are in an unconditioned space. b. Replacement equipment: This flavor of reach code sets certain requirements at time of equipment replacement. This study evaluated space heating and water heating equipment. Where a heat pump measure was found to be cost-effective based on either LSC or On-Bill, this may serve as the basis of a reach code given the following considerations.
i. Where reach codes reduce energy usage and are not just fuel switching, cost-effectiveness calculations are required and must be based on equipment that does not exceed the federal minimum efficiency requirements.
ii. Where reach codes are established using cost-effectiveness based on LSC, utility bill impacts and the owner’s first cost should also be reviewed and considered. 1 TECH Public Reporting Home Page (techcleanca.com)
2 https://www.cpuc.ca.gov/industries-and-topics/electrical-energy/electric-costs/demand-response-dr/demand-flexibility-rulemaking Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Executive Summary
4 California Energy Codes & Standards | A statewide utility program 2024-04-25 iii. A gas path should also be prescriptively allowed to safely satisfy federal preemption requirements considering the CRA v. Berkeley case.3 Additional requirements may apply to the gas path, as described in Section 3.3, as long as the paths are reasonably energy or cost equivalent.
c. “Flexible Path”, minimum energy savings target: This flexible approach establishes a target for required energy savings based on a measure or a set of measures that were found to be cost-effective based on either LSC or On-Bill. A points menu compares various potential upgrades ranging from efficiency, PV, and fuel substitution measures, based on site or source energy savings. The applicant must select upgrades that individually or in combination meet the minimum energy savings target. The maximum target value shown in the Cost-effectiveness Explorer is based on a combination of costeffective, non-preempted measures.

2. Equipment replacement ordinances should consider appropriate exceptions for scenarios where it will be challenging to meet the requirements, such as location of the HPWH, total project cost limitations, or the need for service panel upgrades that wouldn’t have been required as part of the proposed scope of work in absence of the reach code.

3. Consider extending relevant proposals made by the CEC for the 2025 Title 24 code (California Energy Commission, 2023) in ordinances that apply under the 2022 Title 24 code, such as the following:
a. Mandatory ventilation requirements for HPWH installations (Section 110.3(c)7). The cost-effectiveness analysis can be found in the Multifamily Domestic Hot Water CASE report (Statewide Team, 2023). b. Requirement for HERS verified refrigerant charge verification for heat pumps in all climate zones (Table 150.1-A4). The cost-effectiveness analysis can be found in the Residential HVAC Performance CASE report (Statewide Team, 2023).

4. When evaluating reach code strategies, the Reach Codes Team recommends that jurisdictions consider combined benefits of energy efficiency alongside electrification. Efficiency and electrification have symbiotic benefits and are both critical for decarbonization of buildings. As demand on the electric grid is increased through electrification, efficiency can reduce the negative impacts of additional electricity demand on the grid, reducing the need for increased generation and storage capacity, as well as the need to upgrade upstream transmission and distribution equipment.

5. Education and training can play a critical role in ensuring that heat pumps are installed, commissioned, and controlled properly to mitigate grid impacts and maximize occupant satisfaction. Below are select recommended strategies.
a. The Quality Residential HVAC Services Program5 is an incentive program to train California contractors in providing quality installation and maintenance while advancing energy-efficient technologies in the residential HVAC industry. Jurisdictions can market this to local contractors to increase the penetration of contractors skilled in heat pump design and installation. b. Educate residents and contractors of available incentives, tax credits, and financing opportunities. c. Educate contractors on code requirements. Energy Code Ace provides free tools, training, and resources to help Californians comply with the energy code. Contractors can access interactive compliance forms, fact sheets, and live and recorded trainings, among other things, on the website:
https://energycodeace.com/. Jurisdictions can reach out to Energy Code Ace directly to discuss offerings.

6. Health and safety
a. Combustion Appliance Safety and Indoor Air Quality: Implementation of some of the recommended measures will affect the pressure balance of the home which can subsequently impact the safe operation of existing combustion appliances as well as indoor air quality. Buildings with older gas appliances can present serious health and safety problems which may not be addressed in a remodel 3 https://www.publichealthlawcenter.org/sites/default/files/2024-01/CRA-v-Berkeley-Ninth-Circuit-Opinion-Jan2024.pdf 4 This requirement does not show up in the Express Terms for alterations in Section 150.2(b)1F, but the Statewide Reach Codes Team expects that it will be added to the next release of the proposed code language in the 45-day language as it aligns with the proposal made by the Codes and Standards Enhancement Team (Statewide CASE Team, 2023). 5 https://qualityhvac.frontierenergy.com/ Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Executive Summary
5 California Energy Codes & Standards | A statewide utility program 2024-04-25 if the appliances are not being replaced. It is recommended that the building department require inspection and testing of all combustion appliances located within the pressure boundary of the building after completion of retrofit work that involves air sealing or insulation measures. b. Jurisdictions may consider requiring mechanical ventilation in homes where air sealing has been conducted. In older buildings, outdoor air is typically introduced through leaks in the building envelope.

After air sealing a building, it may be necessary to forcefully bring in fresh outdoor air using supply and/or exhaust fans to minimize potential issues associated with indoor air quality.

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 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 CA Building 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. Although a cost-effectiveness study is only required to amend Part 6 of the CA Building Code, this study provides valuable context for jurisdictions pursuing other ordinance paths 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 residents, local leadership, and other stakeholders make informed policy decisions.

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].

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Introduction
6 California Energy Codes & Standards | A statewide utility program 2024-04-25 1 Introduction
This report documents cost-effective measure upgrades in existing single family buildings that exceed the minimum state requirements, the 2022 Building Energy Efficiency Standards, effective January 1, 2023. 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. This report was developed in coordination with the California Statewide Investor-Owned Utilities (IOUs) Codes and Standards Program, key consultants, and engaged cities—collectively known as the Statewide Reach Codes Team.

The focus of this study is on existing single family buildings and does not apply to low or high-rise multifamily buildings.

Each jurisdiction must establish the appropriate structure and threshold for triggering the proposed requirements.

Some common jurisdictional structures include triggering the requirements at major remodels, additions, or date-certain (upgrades must be completed by a specific date). Some of these measures could be triggered with a permit for another specific measure, such as a re-roofing project. The analysis includes scenarios of individual measures and identifies cost-effective options based on the existing conditions of the building in all 16 California Climate Zones (CZ) (see CostEffectiveness Results for a graphical depiction of climate zone locations).

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/.

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.

The California Building Energy Efficiency Standards Title 24, Part 6 (Title 24) (CEC, 2019) is maintained and updated every three years by two state agencies: the California Energy Commission (the Energy Commission) and the Building Standards Commission (BSC). In addition to enforcing the code, local jurisdictions have the authority to adopt local energy efficiency ordinances—or reach codes—that exceed the minimum standards defined by Title 24 (as established by Public Resources Code Section 25402.1(h)2 and Section 10-106 of the Building Energy Efficiency Standards).

Local jurisdictions must demonstrate that the requirements of the proposed ordinance are cost-effective and do not result in buildings consuming more energy than is permitted by Title 24. In addition, the jurisdiction must obtain approval from the Energy Commission and file the ordinance with the BSC for the ordinance to be legally enforceable.

The Department of Energy (DOE) sets minimum efficiency standards for equipment and appliances that are federally regulated under the National Appliance Energy Conservation Act, including heating, cooling, and water heating equipment (E-CFR, 2020). Since state and local governments are prohibited from adopting higher minimum efficiencies than the federal standards require, the focus of this study is to identify and evaluate cost-effective packages that do not include high efficiency heating, cooling, and water heating equipment. High efficiency appliances are often the easiest and most affordable measure to increase energy performance. While federal preemption limits reach code mandatory requirements for covered appliances, in practice, builders may install any package of compliant measures to achieve the performance requirements.

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Methodology and Assumptions
7 California Energy Codes & Standards | A statewide utility program 2024-04-25 2 Methodology and Assumptions

2.1 Analysis for Reach Codes
This section describes the approach to calculating cost-effectiveness including benefits, costs, metrics, and utility rate selection.

2.1.1 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 was used instead of the 2022 version to take advantage of updated weather files and metrics. Site energy results are similar between CBECC-Res 2022 and 2025; however, the 2025 compliance metrics applies assumptions reflective of an electrified future, such as high escalation for natural gas retail rates, which favors electric buildings. In addition, in 2025 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.

Three unique building vintages are considered: pre-1978, 1978-1991, and 1992-2010. The vintages were defined based on review of historic Title 24 code requirements and defining periods with distinguishing features. Prospective energy efficiency measures were identified and modeled to determine the projected site energy (therm and kWh), source energy, GHG emissions, and LSC (long-term systemwide cost) impacts. Annual utility costs were calculated using hourly data output from CBECC, and current (as of 11/01/2023) electricity and natural gas tariffs for each of the investor-owned utilities (IOUs) appropriate for that climate zone.

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 lbs CO2-equivalent (CO2e) emissions.

The Statewide Reach Codes Team designed the analysis approach and selected measures for evaluation based on the 2019 existing building single family reach code analysis (Statewide Reach Codes Team, 2021) and work to support the 2025 Title 24 code development cycle as well as from outreach to architects, builders, and engineers.

2.1.2 Prototype Characteristics
The Energy Commission defines building prototypes which it uses to evaluate the cost-effectiveness of proposed changes to Title 24 requirements. Average home size has steadily increased over time,6 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 1 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 Title 24, Part

6. The CEC has proposed changes to the 2025 Energy Code that would remove the allowance of gas space heating and water heating equipment for additions and instead require additions to follow the same space heating and water heating equipment requirements as new construction (California Energy Commission, 2023). The proposed prescriptive requirements for single family new construction homes are heat pump space heaters and water heaters, with gas equipment only allowed in the performance approach. 6 https://www.census.gov/const/C25Ann/sftotalmedavgsqft.pdf Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Methodology and Assumptions
8 California Energy Codes & Standards | A statewide utility program 2024-04-25 Table 1. Prototype Characteristics
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 costeffective, 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 determined based on either prescriptive requirements from Title 24 that were in effect or standard construction practice during that time period.

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 2 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.
x Individual space conditioning and water heating systems, one per single family building. x Split-system air conditioner with natural gas furnace. o Scenarios with an existing natural gas wall furnace without AC were also evaluated. x Small storage natural gas water heater.
o Scenarios with an existing electric resistance storage water heater were also evaluated. x Gas cooktop, oven, and clothes dryer.

The methodology applied in the analyses begins with a design that matches the specifications as described in Table 2 for each of the three vintages. Prospective energy efficiency measures were modeled to determine the projected energy performance and utility cost impacts relative to the baseline vintage. In some cases, where logical, measures were packaged together.

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades Methodology and Assumptions
9 California Energy Codes & Standards | A statewide utility program 2024-04-25 Table 2. Efficiency Characteristics for Three Vintage Cases Building Component Efficiency
Feature
Vintage Case
Pre-1978 1978-1991 1992-2010
Envelope
Exterior Walls 2x4, 16-inch on center wood frame,
R-0a
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/SHGCb 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 a Pre-1978 wall modeled with R-5 cavity insulation to better align wall system performance with monitored field data and not overestimate energy use. b 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.

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 10 Methodology and Assumptions
California Energy Codes & Standards | A statewide utility program 2024-04-25

2.1.3 Cost-Effectiveness Approach

2.1.3.1 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 (the numerator in the benefit cost calculation):

Utility Bill Impacts (On-Bill): This customer-based lifecycle cost (LCC) approach values energy based upon estimated site energy usage and customer utility bill savings using the latest electricity and natural gas utility tariffs available at the time of writing this report. Total savings are estimated over a 30-year duration and include discounting of future utility costs, as well as assumed energy cost inflation over time.

Long-term Systemwide Cost (LSC): Formerly known as Time Dependent Valuation (TDV) energy cost savings, LSC reflects the Energy Commission’s current 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 efficiency measures in the 2025 Energy Code.

2.1.3.2 Costs
The Reach Codes Team assessed the incremental costs of the measures and packages over a 30-year analysis period. Incremental costs represent the equipment, installation, replacement, and maintenance costs of the proposed measure relative to the 2022 Title 24 Standards minimum requirements or standard industry practices. Present value of replacement cost is included only for measures with lifetimes less than the 30-year evaluation period. In cases where at the end of the analysis period the measure has useful life remaining, the value of this remaining life is calculated and credited in the total lifetime cost.

2.1.3.3 Metrics
Cost-effectiveness is presented using net present value (NPV) and benefit-to-cost (B/C) ratio metrics.

NPV: Equation 1 demonstrates how lifetime NPV is calculated. If the NPV of a measure or package is positive, it is considered cost-effective. A negative value represents a net increase in costs over the 30-year lifetime.

B/C Ratio: This is the ratio of the present value of all benefits to the present value of all costs over 30 years (present value benefits divided by present value costs). A value of one indicates the NPV of the savings over the life of the measure is equivalent to the NPV of the lifetime incremental cost of that measure. A value greater than one represents a positive return on investment. The B/C ratio is calculated according to Equation 2.

Equation 1
ݐݏ݋ܿ ݅݉݁ݐ݈݂݅݁ ݂݋ ݁ݑ݈ܽݒ ݐ݁݊ݏ݁ݎ݌ െ ݐܾ݂݁݊݁݅ ݅݉݁ݐ݈݂݅݁ ݂݋ ݁ݑ݈ܽݒ ݐ݁݊ݏ݁ݎ݌ = ܸܰܲ Equation 2
ݐܾ݂݁݊݁݅ ݅݉݁ݐ݈݂݅݁ ݂݋ ݁ݑ݈ܽݒ ݐ݁݊ݏ݁ݎ݌ = ݋݅ݐܴܽ ݐݏ݋ܥ െ ݋ݐ െ ݐ݂݁݊݁݅ܤ ݐݏ݋ܿ ݅݉݁ݐ݈݂݅݁ ݂݋ ݁ݑ݈ܽݒ ݐ݁݊ݏ݁ݎ݌
Improving the efficiency of a project often requires an initial incremental investment. In most cases the benefit is represented by annual On-Bill utility or LSC savings, and the cost is represented by incremental first cost and future replacement costs. Some packages result in initial construction cost savings relative to the assumed base case scenario, 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 costeffective immediately (i.e., upfront construction cost savings and lifetime energy cost savings), B/C ratio costeffectiveness is represented by “>1”.

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 11 Methodology and Assumptions
California Energy Codes & Standards | A statewide utility program 2024-04-25 The lifetime costs or benefits are calculated according to Equation 3.

Equation 3
௧)ݐܾ݂݁݊݁݅ ݎ݋ ݐݏ݋ܿ ݈ܽݑ݊݊ܣ)෍ = ݐܾ݂݁݊݁݅ ݎ݋ ݐݏ݋ܿ ݅݉݁ݐ݈݂݅݁ ݂݋ ݁ݑ݈ܽݒ ݐ݁݊ݏ݁ݎܲ (1 + ݎ(௧
௡
௧ୀ଴
Where:

1. n = analysis term in years

2. r = discount rate
The following summarizes the assumptions applied in this analysis to both methodologies.

3. Analysis term of 30 years

4. Real discount rate of three percent
Both base case measures and alternative energy efficiency measures may have different lifetime assumptions which impact life cycle economics. Future costing of many of the evaluated electrification measures are only based on current cost assumption, which may be overly conservative as the expected growth in heat pump-based technologies is growing rapidly and will likely lead to future cost reductions (at least relative to current fossil fueled equipment) as production volumes increase.

2.1.4 Utility Rates
In coordination with the CA IOU rate 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 costeffectiveness for the proposed measures and packages. The utility tariffs, summarized in Chapter 6.2, were determined based on the appropriate rate for each case in each territory. 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.

For cases with onsite generation (i.e. solar photovoltaics (PV)), the approved NBT tariffs were applied along with monthly service fees and hourly export compensation rates for 2024.7 In December 2022, the California Public Utilities Commission (CPUC) issued a decision adopting NBT as a successor to NEM 2.0 that went into effect April of 20238.

Utility rates are assumed to escalate over time according to the 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. The Statewide Natural Gas Residential Average Rate for 2023 through 2030 is projected to be 4.6%. The Electric Residential Average Rate for PG&E, SCE and SDG&E for 2023 through 2030 is projected to be 1.8%,1.6% and 2.8% respectively. A second set of escalation rates were also evaluated to demonstrate the impact that utility cost changes have on cost-effectiveness over time. This utility rate escalation sensitivity analysis, presented in Section 3.2.4, was based on those used within the 2025 LSC factors (LSC replaces TDV in the 2025 code cycle) which assumed steep 7 Hourly export compensation rates were based on the NBT spreadsheet model created by E3 for the CPUC. https://www.cpuc.ca.gov/-/media/cpuc-website/divisions/energy-division/documents/net-energy-meteringnem/nemrevisit/nbt-model--12142022.xlsb 8 https://www.cpuc.ca.gov/nemrevisit Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 12 Methodology and Assumptions
California Energy Codes & Standards | A statewide utility program 2024-04-25 increases in gas rates in the latter half of the analysis period. See Appendix 6.2.7 Fuel Escalation Assumptions for details.

Future electricity tariff structures are expected to evolve over time, and the CPUC has an active proceeding to adopt an income-graduated fixed charge that benefits low-income customers and supports electrification measures.10 These were not included in this analysis but may be evaluated later in 2024 once the rates are finalized.

2.1.5 Measure Cost Data Collection Approach
To support this effort, a detailed cost study was completed in the summer of 2023 to gather data from a range of contractors to inform actual installed costs in the areas they provide services. These areas include HVAC, plumbing, envelope and air-sealing, and PV installation. Home performance contractors were also approached to collect this data. Collecting this type of data is challenging, both due to contractor reticence to share cost information and due to the timing of the survey which unfortunately coincided with the summer busy season for most contractors, especially HVAC installers. With these known challenges, the outreach effort focused on leveraging existing relationships between the analysis team and contractors to both gain access and provide assurance that all cost data would remain confidential and aggregated. Contractors that provided feedback were nominally compensated for their time.

The collected cost data was intended to represent recent costs for a “typical” retrofit installation. Each home in which a contractor does work has different site-specific issues that will likely affect costs. In addition, different jurisdictions have different levels of building department installation oversight and permit fees. Finally, each contractor typically has a different manufacturer product line they prefer to install. All these factors will influence installed costs11.

The most detailed and broad cost request was for the HVAC contractors, as there are a wide range of equipment replacement scenarios available for an existing ducted gas furnace with central split-system air conditioning. Options range from a base case scenario (like for like swap out), split-system heat pump replacement, dual fuel heat pumps (DFHP), ducted mini-split heat pumps, non-ducted mini-splits, etc. For plumbing contractors, a range of scenarios existed for water heater replacements including like-for-like replacement, HPWHs (in different locations- garage, indoor), need for electrical upgrade for HPWH installation, need for HPWH ducting, etc. Envelope measures focused on attic and wall insulation, window replacement, re-roofing (with Cool Roof materials or not), and attic ceiling plane airsealing. PV costing included different system sizes, panel upgrades costs, and battery costs. Home performance contractors were asked to provide as much data as they could on the different measure options. All costing information requested was intended to represent most recent installations, in an effort to capture current pricing as best as possible.

The contractors that responded with their cost estimates work in different regions of the state, operate in different markets with (potentially) different local efficiency incentives, do varying amounts of work based on the size of their company, target different market demographic sectors, and install different brands of equipment. All these factors will contribute to price variability. The Team considered applying climate zone specific cost adjustments to reflect some of these differences, but ultimately decided not to since a climate zone is not a monolithic entity with uniform customer pricing throughout. The Team recognizes that “zip code” pricing is a reality, but for simplicity, as well as consistency with Title 24, Part 6 code development costing approaches, applied uniform statewide costs to all measures.

2.2 Measure Details and Cost
This section describes the details of the measures and documents incremental costs. All measure costs were obtained from the contractor survey unless otherwise noted. All contractor provided costs reflect the cost to the customer and 10 https://www.cpuc.ca.gov/industries-and-topics/electrical-energy/electric-costs/demand-response-dr/demandflexibility-rulemaking 11 One HVAC contractor mentioned that equipment brand alone may contribute to a +/-%5 variation in the total bid cost.

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 13 Methodology and Assumptions
California Energy Codes & Standards | A statewide utility program 2024-04-25 include equipment, labor, permit fees, and required HERS testing. Additional details of the measures can be found in Appendix Section Error! Reference source not found..

All measures are evaluated assuming they are not otherwise required by Title 24. For example, duct sealing is required by code whenever HVAC equipment is altered. For this analysis duct sealing was evaluated for those projects where it is not already triggered by code (i.e., no changes to the heating or cooling equipment). Where appropriate, measure requirements align with those defined in Title 24. In some cases, cost-effective measures were identified that exceed Title 24 requirements, such as attic insulation, cool roofs, and duct sealing.

2.2.1 Building Envelope & Duct Measures
The following are descriptions of each of the efficiency upgrade measures applied in this analysis.

Attic Insulation: Add attic insulation in buildings with vented attic spaces to meet either R-38 or R-49. The pre-1978 vintage assumes an existing condition of R-11, the 1978-1991 vintage assumes an existing condition of R-19, and the 1992-2010 vintage assumes R-30 as the existing insulation level. For pre-1978 vintage homes this measure was also evaluated to include air sealing of the attic. A 14% leakage reduction was modeled such that 15 ACH50 was reduced to 12.9 ACH50 in this measure. The costs for this measure include removing existing insulation.

Air Sealing and Weather-stripping: Apply air sealing practices throughout all accessible areas of the building. For this study, it was assumed that older vintage homes would be leakier than newer buildings and that approximately 30 percent improvement in air leakage is achievable through air sealing of all accessible areas. For modeling purposes, it was assumed that air sealing can reduce infiltration levels from 15 to ten air changes per hour at 50 Pascals pressure difference (ACH50) in the oldest vintages (pre-1978), to ten to seven ACH50 for the 1978-1991 vintage, and seven to five ACH50 in the 1992-2010 vintage.

Cool Roof: For steep slope roofs, install a roofing product rated by the Cool Roof Rating Council (CRRC) with an aged solar reflectance of 0.20 or 0.25 and thermal emittance of 0.75 or higher. This measure only applies to buildings that are installing a new roof as part of the scope of the remodel; the cost and energy savings associated with this upgrade reflects the incremental step between a standard roofing product with one that is CRRC rated with an aged solar reflectance of 0.20 or 0.25. This is similar to cool roof requirements in 2022 Title 24 Section 150.2(b)1Ii but assumes a higher solar reflectance.

Radiant Barrier: Add radiant barrier to any existing home vintage. This measure only applies to buildings that are installing a new roof as part of the scope of the remodel; the cost and energy savings associated with this upgrade reflects the incremental step between a standard roofing product with one that includes a laminated radiant barrier.

Raised Floor Insulation: In existing homes with raised floors and no insulation (pre-1978 and 1978-1991 vintages), add R-19 insulation. An upgraded R-30 floor insulation, assuming no current insulation, was evaluated in the pre-1978 and 1978-1991 vintages.

Wall Insulation: Blow-in R-13 wall insulation in existing homes without wall insulation (pre-1978 vintages).

Window Replacement: Replace existing windows with a non-metal dual-pane product, which has a U-factor equal to

0.28 Btu/hour-ft2-°F or lower and a Solar Heat Gain Coefficient (SHGC) equal to 0.23 or lower, except in heating dominated climates (Climate Zones 1, 3, 5, and 16) where an SHGC of 0.35 was evaluated.

Duct Sealing, New Ducts, and Duct Insulation: Air seal all ductwork to meet the requirements of the 2022 Title 24, Part 6 Section 150.2(b)1E. For this analysis, final duct leakage values of ten percent (proposed revised leakage rate for 2022 Title 24) was evaluated. The pre-1978 and 1978-1992 vintages assume leaky existing ducts (25-30% leakage).

The 1992-2010 vintage assumes moderately leaky existing ducts (15-20% leakage).

Replacing existing ductwork with entirely new ductwork to meet Sections 150.2(b)1Di and 150.2(b)1Diia of the 2022 Title 24 was also evaluated. This assumed new ducts meet 5% duct leakage and the option of R-6 and R-8 duct insulation in all climate zones.

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 14 Methodology and Assumptions
California Energy Codes & Standards | A statewide utility program 2024-04-25 Table 3 summarizes the cost assumptions for the building envelope and HVAC duct improvement measures evaluated.

All the measures in Table 3 assume a 30-year effective useful life.

Table 3. Measure Cost Assumptions – Efficiency & Duct Measures Measure Performance Level
Incremental Cost –
Single Family Building
Pre 1978 1978 – 1991 1992 - 2010
Wall Insulation R-13 $2,950 N/A N/A
Raised Floor
Insulation
R-19 $3,633 $3,633 N/A
R-30 $4,113 $4,113 $4,113
Attic Insulation
R-38 $6,762 $2,555 $1,781
R-49 $7,446 $3,612 $1,827
Air Sealing
10 ACH50 $4,684 N/A N/A
7 ACH50 N/A $4,684 N/A
5 ACH50 N/A N/A $4,684
Cool Roof

0.25 Aged Solar Reflectance
CZs 1-3,5-7,16 $2,407 $2,407 $2,407

0.25 Aged Solar Reflectance
CZs 4, 8-15 $1,203 $1,203 $1,203
Window
U-factor/SHGC

0.28 U-factor. 0.23 SHGC in
CZs 2,4,6-15. $11,463 $11,463 $11,463

0.28 U-factor. 0.35 SHGC in
CZs 1,3,5,26 $11,871 $11,871 $11,871
Radiant Barrier Add Radiant Barrier $893 $893 $893
Duct Sealing 10% nominal airflow $2,590 $2,590 $1,400
All New Duct
System
R-6 ducts;
5% duct leakage $4,808 $4,808 $4,808
R-8 ducts;
5% duct leakage $6,311 $6,311 $6,311

2.2.2 PV Measures
Installation of on-site PV is required in the 2022 Title 24 code for new construction homes, but there are no PV requirements for additions or alterations to existing buildings. PV was evaluated in CBECC-Res according to the California Flexible Installation (CFI) 1 assumptions and 98% solar access. To meet CFI eligibility, the requirements of 2022 Reference Appendices JA11.2.2 (California Energy Commission, 2021b) must be met. A 3 kW PV system was modeled both as a standalone measure as well as coupled with heat pump installations.

The costs for installing PV are summarized in Table 4. They include the first cost to purchase and install the system, future inverter replacement costs, and annual maintenance costs. Upfront solar PV system costs are estimated from the contractor surveys to be $4.58/WDC and are reduced by 30 percent to account for the federal income Residential Clean Energy Credit. The solar panels are estimated to have an effective useful life of 30 years and the inverter 25 years. The inverter replacement cost of $7,000 (future value) is also from the contractor surveys. System maintenance costs are taken from the 2019 PV CASE Report (California Energy Commission, 2017) and are assumed to be Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 15 Methodology and Assumptions
California Energy Codes & Standards | A statewide utility program 2024-04-25 $0.31/WDC present value. These costs do not include costs associated with electrical panel upgrades, which will be necessary in some instances.

Table 4. Measure Descriptions & Cost Assumptions – PV
Measure Performance
Level
Incremental Cost
Pre 1978 1978 – 1991 1992 - 2010
PV 3 kW $9,608

2.2.3 Equipment Fuel Substitution Measures – Heat Pump Equipment The fuel substitution measures are evaluated as replacements at the end of the life of the existing equipment. This means the baseline compared against is usually a like-for-like change-out of the natural gas equipment, and the upgrade is a heat pump.

For most of the space heating and water heating cases, costs for electrical service panel upgrades are not included as it is assumed many existing homes have the service capacity to support converting one appliance from gas to electric.

For homes with existing air conditioners, any incremental electric capacity necessary to support a heat pump space heater is marginal. The same applies for homes with existing electric resistance equipment. Section 3.2.4 presents the impacts for select cases where an upgrade to the electric panel is required.

Heat Pump Space Heating
All the heat pump space heater (HPSH) measures are described below. All were evaluated with HERS verified refrigerant charge aligned with the proposed code requirements for the 2025 Title 24 code. Dual fuel heat pumps (DFHPs) were controlled to lockout furnace operation above 35°F.

DFHP (Existing Furnace): Replace existing ducted air conditioner (AC) with an electric heat pump and install controls to operate the heat pump to use the existing gas furnace for backup heat. 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).

DFHP (New Furnace): Replace existing ducted AC and natural gas furnace with an electric heat pump and new gas furnace plus controls to operate the heat pump and use the new gas furnace for backup heat. A minimum federal efficiency (14.3 SEER2, 11.7 EER2, 7.5 HSPF2) heat pump and furnace (80 AFUE) were evaluated to replace existing equipment. Savings are compared to a new ducted AC and natural gas furnace (14.3 SEER2, 11.7 EER2, 80 AFUE).

Heat Pump Space Heater: Replace existing ducted AC and natural gas furnace with an electric heat pump. Minimum federal efficiency (14.3 SEER2, 11.7 EER2, 7.5 HSPF2) and 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).

Ducted Mini-Split Heat Pump (MSHP): Replace existing ducted AC and natural gas furnace with a ducted high efficiency MSHP (16.5 SEER2, 12.48 EER2, 9.5 HSPF2). Savings are compared to a new ducted AC and natural gas furnace (14.3 SEER2, 11.7 EER2, 80 AFUE).

Ductless MSHP: In a home without AC, replace existing wall furnace with a ductless MSHP. A standard efficiency unit meeting minimum federal efficiency standards (14.3 SEER2, 11.7 EER2, 7.5 HSPF2) was evaluated by modeling the variable capacity heat pump (VCHP) compliance credit in CBECC-Res. A premium, higher efficiency upgrade was also Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 16 Methodology and Assumptions
California Energy Codes & Standards | A statewide utility program 2024-04-25 evaluated using CBECC-Res’ detailed VCHP model12 by simulating the performance of a representative high efficiency product (14.3 SEER2, 11.7 EER2, 7.5 HSPF2). Savings are compared to a new natural gas wall furnace with fan distribution (75% AFUE) and window AC (9 CEER).

Over the 30-year analysis period, certain changes are assumed when the equipment is replaced that impact both lifetime costs and energy use. Table 5 presents the lifetime scenario for the DFHP (existing furnace) measure. 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 AFUE13. 5 years later the air conditioner reaches the end of its life and is replaced with a new air conditioner.

For the DFHP upgrade case, after 10 years when the furnace fails it’s expected that the furnace will be 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 would be replaced with a new aftermarket unit and would operate another 5 years until the heat pump fails and is replaced with a new heat pump and air handler.

The other ducted heat pump cases similarly apply a 95 AFUE furnace in the baseline when the furnace reaches its EUL after 20 years.

Table 5. Lifetime Analysis Replacement Assumptions for DFHP (Existing Furnace) Scenario Year Baseline Upgrade
0 AC fails, install new AC,
keep existing furnace
AC fails, install new HP,
keep existing furnace
10 Furnace fails, install new
95AFUE furnace
Furnace fails, replace fan
motor
15 AC fails, install new AC HP fails, install new HP
and air handler
Costs were applied based on the system capacity from heating and cooling load calculations in CBECC-Res as presented in Table 6. 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 demonstrated that Climate Zones 2 - 15 were cooling-dominated while Climate Zones 1 and 16 were heating-dominated. In the heating dominated climate zones the heat pump needed to be upsized relative to an air conditioner that only provides cooling. 12 The detailed VCHP option allows for the user to input detailed specifications based on the published National Energy Efficiency Partnership (NEEP) manufacturer specific performance data. It is not currently available for compliance analysis.
13 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%20living%20space.

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 17 Methodology and Assumptions
California Energy Codes & Standards | A statewide utility program 2024-04-25 Table 6. 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
Table 7 presents estimated first and lifetime costs for the various ducted 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 8 presents estimated first and lifetime costs for the ductless baseline and 2 heat pump scenarios, also for 4-ton heat pump equipment. EULs are based on 20 years for the gas wall furnace, 10 years for the window AC, and 15 years for the heat pump.14
14 The gas wall furnace and heat pump EULs were based on DEER (California Public Utilities Commission, 2021b).

Gas wall furnace lifetime was assumed to be the same as for central gas furnace equipment. Room air conditioner EUL was based on the DOE’s latest rulemaking for room air conditioned (Department of Energy, 2023). DOE determined an average lifetime of 9.3 years, which was rounded up to 10 years for this analysis.

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 18 Methodology and Assumptions
California Energy Codes & Standards | A statewide utility program 2024-04-25 Table 7. Ducted HVAC Measure Cost Assumptions – 4-Ton Electric Replacements Case AC + Coil
Gas
Furnace
/AC
DFHP
(Existing
Furnace)
DFHP (New
Furnace)
Min. Eff.

Heat Pump
High Eff.

Heat
Pump
Ducted
MSHP
Base Case - - AC + Coil
Gas
Furnace
/AC
Gas
Furnace
/AC
Gas
Furnace
/AC
Gas
Furnace
/AC
First Cost $10,402 $16,653 $12,362 $20,676 $17,825 $20,802 $18,075 Replacement Cost
(Future Value) $19,365 $19,365 $19,025 $19,025 $16,825 $19,802 $18,075 Replacement Cost
(Present Value) $13,346 $11,639 $12,334 $12,897 $10,800 $12,710 $11,601 Remaining Value
at Year 30 $0 ($1,846) $0 ($1,846) $0 $0 $0
Total Lifecycle
Cost $23,748 $26,446 $24,696 $31,727 $28,625 $33,512 $29,676 Incremental Cost - - $948 $5,281 $2,179 $7,066 $3,230
Table 8. Non-Ducted HVAC Measure Cost Assumptions – 4-Ton Electric Replacements Wall Furnace
+ Window AC
Min. Eff.

Ductless
MSHP
High Eff.

Ductless
MSHP
First Cost $4,075 $17,412 $21,342
Replacement Cost (Future Value) $4,075 $17,412 $21,342
Replacement Cost (Present Value) $3,365 $11,176 $13,698 Remaining Value at Year 30 ($532) $0 $0
Total Lifecycle Cost $6,908 $28,588 $35,040
Incremental Cost - $21,680 $28,132
Heat Pump Water Heating:

The heat pump water heater (HPWH) measures are described below, and costs are presented in Table 9 and Table

10. The most typical scenario in California is a home with existing natural gas storage tank water heaters. However, there are also many existing homes with existing electric resistance storage tank water heaters and this work considers both baselines. This analysis evaluates the following 65-gallon replacement HPWHs:

1. HPWH that meets the federal minimum efficiency requirements of UEF 2.0

2. HPWH that meets the Northwest Energy Efficiency Alliance (NEEA)15 Tier 3 rating (3.45 UEF)

3. HPWH that meets the NEEA Tier 4 rating and that has demand response (DR) or load shifting control capability (4.02 UEF)

4. 120V HPWH that meets the NEEA Tier 3 rating (3.3 UEF). 15 Based on operational challenges experienced in the past, NEEA established rating test criteria to ensure newly installed HPWHs perform adequately, especially in colder climates. The NEEA rating requires an Energy Factor equal to the ENERGY STAR® performance level and includes requirements regarding noise and prioritizing heat pump use over supplemental electric resistance heating.

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 19 Methodology and Assumptions
California Energy Codes & Standards | A statewide utility program 2024-04-25 The four cases above were evaluated with the HPWH located within an attached garage. Additionally, three separate cases for the federal minimum efficiency HPWH were analyzed to consider the impacts of location on performance and cost-effectiveness. These locations included the following:

1. Exterior closet.

2. Interior closet, no ducting.

3. Interior closet, ducted to the outside.

Additional costs for providing electrical wiring to these locations and for providing ductwork were included. Savings are compared to a new 50-gallon natural gas storage water heater (UEF 0.63) or a new 50-gallon electric water heater (UEF 0.92).

For this analysis, a HPWH that just meets the federal minimum efficiency standards of close to 2.0 Uniform Energy Factor (UEF) was evaluated in order to satisfy preemption requirements. However, the Reach Codes Team is not aware of any 2.0 UEF products that are available on the market. The lowest UEF reported for certified products in the Northwest Energy Efficiency Alliance (NEEA)16 database is 2.73. In fact, of the four certification tiers offered by NEEA for high efficiency HPWHs, those meeting Tier 3 or Tier 4 are the dominant products on the market today. According to NEEA all major HPWH manufacturers are represented in NEEA’s qualified product list17 and there are fewer than 10 integrated products certified as Tier 1 or Tier 2, all of which have UEFs greater than 3.0.18 Therefore, in this analysis, we refer to the NEEA rated HPWH as the “market standard” HPWH.

The HPWH costs for the 120V and NEEA certified units are based on a larger (60 or 65 gallon) HPWH, as most contractors are upsizing the HPWH tank size relative to an equal volume, but higher capacity gas storage water heater.

Costs include all material and installation labor including providing a new 240 V electrical service to the water heater location (not needed for the 120V product). Water heating equipment lifetimes are based on DOE’s recent water heater rulemaking (Department of Energy, 2022) and assume 15-year EULs for both the baseline water heaters and the HPWHs.19 Future replacement costs for 240V HPWHs do not include any initial costs associated with 240V electrical service, condensate disposal, etc.

Table 9. Water Heating Measure Cost Assumptions – Existing Gas Gas
Storage
Water
Heater
240V
Fed.

Min.

HPWH
240V
Market
Std. NEEA
HPWH
240V
Market
Std. NEEA
HPWH +
DR
120V
Market
Std. NEEA
HPWH
240V Fed.

Min.

HPWH,
Exterior
Closet
240V Fed.

Min. HPWH,
Interior
Closet, Not
Ducted
240V Fed.

Min. HPWH,
Interior
Closet,
Ducted
First Cost $2,951 $7,283 $8,144 $8,144 $5,844 $7,702 $7,363 $8,442 Replacement Cost
(Future Value) $2,951 $6,413 $7,274 $7,274 $5,101 $6,413 $6,413 $6,413 Replacement Cost
(Present Value) $1,894 $4,116 $4,669 $4,669 $3,274 $4,116 $4,116 $4,116 Total Lifecycle Cost $4,845 $11,399 $12,813 $12,813 $9,118 $11,818 $11,479 $12,558 Incremental Cost - $6,554 $7,968 $7,968 $4,273 $6,973 $6,634 $7,713 16 Based on operational challenges experienced in the past, NEEA established rating test criteria to ensure newly installed HPWHs perform adequately, especially in colder climates. The NEEA rating requires products comply with ENERGY STAR and includes requirements regarding noise and prioritizing heat pump use over supplemental electric resistance heating.
17 https://neea.org/success-stories/heat-pump-water-heaters 18 As of 12/21/23: https://neea.org/img/documents/residential-unitary-HPWH-qualified-products-list.pdf 19 The recent DOE rulemaking references a lifetime of 14 years for gas storage water heaters and 14.8 years for electric storage water heaters. 15 years for each was used in this analysis for both types for simplification.

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 20 Methodology and Assumptions
California Energy Codes & Standards | A statewide utility program 2024-04-25 Table 10 presents similar costs to Table 9, except that the costs assume replacement of an existing 50-gallon electric storage water heater and does not include the 240 V electrical service cost.

Table 10. Water Heating Measure Cost Assumptions – Existing Electric Resistance Electric
Storage
Water
Heater
240V
Fed. Min.

HPWH
240V
Market
Std. NEEA
HPWH
240V
Market
Std. NEEA
HPWH +
DR
120V
Market
Std. NEEA
HPWH
240V Fed.

Min.

HPWH,
Exterior
Closet
240V Fed.

Min. HPWH,
Interior
Closet, Not
Ducted
240V Fed.

Min. HPWH,
Interior
Closet,
Ducted
First Cost $2,583 $6,413 $7,274 $7,274 $5,101 $6,413 $6,413 $7,492 Replacement Cost
(Future Value)
$2,583 $6,413 $7,274 $7,274 $5,101 $6,413 $6,413 $6,413 Replacement Cost
(Present Value)
$1,658 $4,116 $4,669 $4,669 $3,274 $4,116 $4,116 $4,116 Total Lifecycle Cost $4,241 $10,529 $11,943 $11,943 $8,375 $10,529 $10,529 $11,608 Incremental Cost - $6,288 $7,702 $7,702 $4,134 $6,288 $6,288 $7,367 Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 21 Results
California Energy Codes & Standards | A statewide utility program 2024-04-25 3 Results
The primary objective of the evaluation is to identify cost-effective energy upgrade measures and packages for existing single family buildings, to support the design of local ordinances requiring upgrades, which may be triggered by different events, such as at the time of a significant remodel or at burnout of mechanical equipment. In this report, the 1992-2010 vintage is shown for the equipment measures because it is the most conservative case (lowest loads), while the pre-1978 vintage is shown for the envelope and duct measures because some of those measures only apply to the pre-1978 vintage. 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/.

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 22 Results
California Energy Codes & Standards | A statewide utility program 2024-04-25

3.1 Cost-Effectiveness Results
The extensive analysis for this type of report leads to an overwhelming number of scenarios including different base cases, house vintages, replacement options, and climate zones. To simplify the reporting, the Statewide Reach Codes Team has relied on graphical representation of select key cases indicating high level measure cost effectiveness from either an On-Bill perspective, an LSC perspective, both metrics, or neither. Figure 1 through Figure 13 present this reduced set of results of the LSC and On-Bill cost-effectiveness conclusions across the 16 climate zones. In the cases where there are multiple utilities serving a single climate zone, an asterisk “*” label is added to separately show the alternate utility cases. These graphs provide a general sense of the findings. 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/.

3.1.1 HPSH Measures
Figure 1 through Figure 5 show the cost-effectiveness of space heating equipment replacement measures for the 1992-2010 vintage including the following cases. The 1992-2010 vintage results are presented here as this is the most conservative scenario for HPSH measures. In general, where a HPSH measure is cost-effective for a new home it was also found to be cost-effective for older homes.
x Dual fuel heat pump with existing furnace as backup.
x Standard efficiency ducted central heat pump replacement. x High efficiency ducted central heat pump replacement. x Ducted mini-split heat pump replacement.
x Standard efficiency ducted central heat pump replacement with 3kW PV system.

Figure 1: DFHP with Existing Furnace Figure 2: Standard Efficiency HPSH Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 23 Results
California Energy Codes & Standards | A statewide utility program 2024-04-25 Figure 3: High Efficiency HPSH Figure 4: Ducted MSHP
Figure 5: HPSH + PV
Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 24 Results
California Energy Codes & Standards | A statewide utility program 2024-04-25

3.1.2 HPWH Measures
Figure 6 through Table 11 show the cost-effectiveness of water heater measures for the 1992-2010 vintage including the following cases. HPWH energy savings and LSC cost-effectiveness is not sensitive to home vintage but rather depends on the magnitude of hot water loads, which are typically driven by the number of occupants. On-Bill costeffectiveness does vary slightly by vintage due to the impact of the electrification tariff relative to the load profile of the existing home. The impact is largest for the HPWH + PV case where On-Bill cost-effectiveness improves for older homes or homes with overall higher energy use resulting in less exports to the grid for a fixed size PV system. x 240V federal minimum HPWH
x 240V market standard NEEA HPWH
x 120V market standard NEEA HPWH
x 240V federal minimum HPWH with 3kW PV
Figure 6: 240V Federal Minimum HPWH Figure 7: 240V Market Standard NEEA HPWH Figure 8: 120V Market Standard NEEA HPWH Figure 9: 240V Federal Minimum HPWH + PV Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 25 Results
California Energy Codes & Standards | A statewide utility program 2024-04-25 x Envelope and Duct Measures
Figure 10 through Figure 13 show the cost-effectiveness results of envelope and duct measures for the pre-1978 vintage including the following measures. The pre-1978 vintage is presented as representing the most favorable existing conditions for cost-effective upgrades. Newer homes with higher performing envelope may still benefit from these types of upgrade measures, but cost-effectiveness is reduced. Some measures, like R-13 wall insulation, aren’t applicable to newer homes which would have been constructed originally with insulated walls. x New R-6 ducts
x 10% duct leakage
x R-13 wall insulation
x R-49 attic insulation
Figure 10: R-6 Ducts Figure 11: 10% Duct Leakage
Figure 12: R-13 Wall Insulation Figure 13: R-49 Attic Insulation Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 26 Results
California Energy Codes & Standards | A statewide utility program 2024-04-25

3.2 Climate Zone Case Studies
To better understand the details of the results, a few climate zones were selected to provide a more detailed presentation of cost-effectiveness results. Section 3.2.1 through 3.2.3 show the first-year incremental cost, first-year utility savings, and NPV for a variety of cases. Section 3.2.4 shows the sensitivity of the cost effectiveness results due to varying utility escalation rates, the impact of CARE rates, future equipment cost assumptions, and the need for electrical panel upgrades. The climate zones were selected to be representative of areas of significant reach code activity. Please refer to the Cost-Effectiveness Explorer (Statewide Reach Codes, 2023) or the source dataset for the full analysis.

3.2.1 HPSH Cost-Effectiveness
Cost-effectiveness of heat pump space heating measures for Climate Zones 12 and 16 is summarized in Table 11 and Table 12 below. In Climate Zone 12, HPSH measures are cost-effective based on LSC in all cases except the ductless MSHP cases and are cost-effective On-Bill with SMUD rates in all cases except the DFHP case with a new furnace and the ductless MSHP cases. These measures are cost-effective On-Bill with PGE for the DFHP with an existing furnace and ducted MSHP measures. Climate Zone 16 provides an example of HPSH cost-effectiveness in a cold climate where almost all HPSH measures are cost effective based on LSC but not cost-effective On-Bill.

Table 11. HPSH CZ 12 [1992-2010]
Measure
First
Incremental
Cost
2025 LSC
NPV

PGE SMUD
First-year
Utility
Savings
On-Bill
NPV
First-year
Utility
Savings
On-Bill
NPV
DFHP Existing Furnace $1,960 $7,093 ($19) $1,633 $247 $7,693 DFHP New Furnace $4,023 $3,915 ($34) ($3,134) $234 $2,979 HPSH (Std Efficiency) $1,172 $6,990 ($147) ($2,151) $246 $6,812 HPSH (High Efficiency) $4,149 $5,366 $13 ($3,368) $300 $3,160 Ducted MSHP $1,421 $9,136 $10 $378 $298 $6,951
Ductless MSHP (Std Efficiency) $13,336 ($9,175) $30 ($18,039) $276 ($12,428) Ductless MSHP (High Efficiency) $17,266 ($6,753) $409 ($15,853) $423 ($15,532) HPSH + PV $10,780 $5,289 $452 ($59) $885 $9,821
Table 12. HPSH CZ 16 [1992-2010]
Measure
First
Incremental
Cost
2025 LSC
NPV
PGE
First-year
Utility Savings On-Bill NPV
DFHP Existing Furnace $2,397 $7,289 ($116) ($1,891)
DFHP New Furnace $4,757 $2,457 ($133) ($6,322)
HPSH (Std Efficiency) $2,725 $11,142 ($480) ($8,532)
HPSH (High Efficiency) $5,701 $12,099 ($204) ($7,125)
Ducted MSHP $2,155 $16,554 ($221) ($2,853)
Ductless MSHP (Std Efficiency) $13,336 ($134) ($170) ($19,742) Ductless MSHP (High Efficiency) $17,266 $9,397 $539 ($10,031) HPSH + PV $12,333 $10,640 $316 ($1,949)
Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 27 Results
California Energy Codes & Standards | A statewide utility program 2024-04-25

3.2.2 HPWH Cost-Effectiveness
Cost-effectiveness of heat pump water heating measures for Climate Zones 12 and 16 is summarized in Table 13 and Table 14 below. This sensitivity study looks at a wider range of HPWH tank locations and whether or not the unit has ducting for supply and exhaust air. All the HPWH measures in Climate Zones 12 and 16 are cost effective based on LSC.

Table 13. HPWH CZ 12 [1992-2010]
Measure
First
Incremental
Cost
2025 LSC
NPV

PGE SMUD
First-Year
Utility
Savings
On-Bill
NPV
First-Year
Utility
Savings
On-Bill
NPV
240V Fed. Min. HPWH $4,332 $3,536 ($213) ($8,738) $191 $477 240V Market Std. NEEA
HPWH $5,193 $4,304 ($82) ($7,164) $230 ($56)
240V Market Std. NEEA
HPWH + DR $5,193 $5,536 ($21) ($5,773) $248 $362
120V Market Std. NEEA
HPWH $2,893 $9,730 ($2) ($1,651) $254 $4,203
240V Fed. Min. HPWH
(Exterior Closet) $4,751 $2,834 ($224) ($9,431) $186 ($78) 240V Fed. Min. HPWH
(Interior Closet) $4,413 $3,123 ($71) ($6,138) $188 ($235) 240V Fed. Min. HPWH
(Interior Closet, ducted) $5,492 $3,359 ($202) ($9,505) $205 ($231) 240V Fed. Min. HPWH + PV $13,940 $3,567 $577 ($2,300) $831 $3,486 Table 14. HPWH CZ 16 [1992-2010]
Measure
First
Incremental
Cost
2025 LSC
NPV
PGE
First-Year Utility
Savings On-Bill NPV
240V Fed. Min. HPWH $4,332 $4,186 ($250) ($9,307)
240V Market Std. NEEA HPWH $5,193 $4,088 ($160) ($8,652) 240V Market Std. NEEA HPWH + DR $5,193 $5,653 ($79) ($6,804 120V Market Std. NEEA HPWH $2,893 $10,646 ($13) ($1,602) 240V Fed. Min. HPWH (Exterior Closet) $4,751 $3,317 ($268) ($10,154) 240V Fed. Min. HPWH (Interior Closet) $4,413 $5,004 ($18) ($4,690) 240V Fed. Min. HPWH (Interior Closet,
ducted) $5,492 $4,857 ($202) ($9,174)
240V Fed. Min. HPWH + PV $13,940 $5,049 $620 ($1,043)
Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 28 Results
California Energy Codes & Standards | A statewide utility program 2024-04-25

3.2.3 Envelope & Duct Improvement Cost-Effectiveness
Cost-effectiveness of envelope and duct measures for Climate Zones 3, 10, and 12 is summarized in Table 15 through Table 17.

Table 15. Envelope and Duct Measures CZ 3 [Pre-1978]
Measure
First
Incremental
Cost
2025 LSC
NPV
PG&E
First-year Utility
Savings On-Bill NPV
R-6 Ducts $4,808 $2,851 $188 $463
R-8 Ducts $6,311 $1,747 $198 ($776)
10% Duct Sealing $2,590 $1,956 $104 $397
R-13 Wall Insulation $2,950 $3,476 $144 $1,221
R-38 Attic Insulation $6,762 ($1,567) $127 ($3,178)
R-49 Attic Insulation $7,446 ($1,768) $139 ($3,520)
R-30 Raised Floor Insulation $4,113 $9,008 $224 $2,975
Cool Roof (0.20 Ref) $893 ($2,419) ($18) ($1,811)
Table 16. Envelope and Duct Measures CZ 10 [Pre-1978]
Measure
First
Incremental
Cost
2025 LSC
NPV

SCE/SCG SDGE
First-year
Utility
Savings
On-Bill
NPV
Firstyear
Utility
Savings
On-Bill
NPV
R-6 Ducts $4,808 $7,463 $783 $13,168 $1,100 $22,155
R-8 Ducts $6,311 $6,326 $800 $12,076 $1,125 $21,268
10% Duct Sealing $2,590 $3,438 $370 $5,969 $518 $10,166 R-13 Wall Insulation $2,950 $1,795 $179 $1,476 $250 $3,494 R-38 Attic Insulation $6,762 $664 $416 $2,951 $582 $7,654 R-49 Attic Insulation $7,446 $796 $467 $3,435 $655 $8.756 R-30 Raised Floor Insulation $4,113 ($999) ($29) ($4,235) ($46) ($4,687) Cool Roof (0.20 Ref) $893 $428 $174 $2,647 $246 $4,656
Table 17. Envelope and Duct Measures CZ 12 [Pre-1978]
Measure
First
Incremental
Cost
2025 LSC
NPV

PG&E SMUD
First-year
Utility
Savings
On-Bill
NPV
Firstyear
Utility
Savings
On-Bill
NPV
R-6 Ducts $4,808 $11,609 $804 $14,727 $413 $5,816
R-8 Ducts $6,311 $10,722 $828 $13,849 $427 $4,711
10% Duct Sealing $2,590 $6,418 $397 $7,280 $222 $3,281
R-13 Wall Insulation $2,950 $5,774 $262 $4,054 $187 $2,342 R-38 Attic Insulation $6,762 $3,727 $499 $5,461 $261 $19 R-49 Attic Insulation $7,446 $4,092 $552 $6,063 $288 $33 R-30 Raised Floor Insulation $4,113 $5,245 $27 ($1,176) $156 $1,175 Cool Roof (0.20 Ref) $893 ($354) $154 $2,123 $44 ($386) Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 29 Results
California Energy Codes & Standards | A statewide utility program 2024-04-25

3.2.4 Sensitivities
Table 18 shows the On-Bill NPV results of Climate Zone 12 with PG&E utility rates and the impacts of escalation rates, and CARE rates. The “Standard Results” in Table 18 assumes the escalation rates used in the analysis presented elsewhere in this report. Table 19 shows the impact of electrical panel upgrades. The “Standard Results” in Table 19 does not assume a panel upgrade is required.

Table 18. Sensitivity Analysis Results for On-Bill NPV Cost-Effectiveness in Climate Zone 12, PG&E Measure Vintage Standard
Results
2025 LSC
Escalation CARE
DFHP Existing Furnace 1992-2010 $1,063 $8,443 $1,884
DFHP New Furnace 1992-2010 ($6,770) $383 ($5,846)
HPSH (Std Efficiency) 1992-2010 ($2,151) $6,011 ($220)
HPSH (High Efficiency) 1992-2010 ($3,368) $4,987 ($2,721) Ducted MSHP 1992-2010 $378 $8,729 $1,057
Ductless MSHP (Std Efficiency) 1992-2010 ($18,039) ($10,732) ($17,623) Ductless MSHP (High Efficiency) 1992-2010 ($15,853) ($8,091) ($18,460) HPSH + PV 1992-2010 ($59) $8,822 ($1,255)
240V Fed. Min. HPWH 1992-2010 ($8,738) ($2,433) ($6,448) 240V Market Std. NEEA HPWH 1992-2010 ($7,164) ($694) ($5,918) 240V Market Std. NEEA HPWH + DR 1992-2010 ($5,773) $770 (5,014) 120V Market Std. NEEA HPWH 1992-2010 ($1,651) $4,930 (1,038) 240V Fed. Min. HPWH (Exterior Closet) 1992-2010 ($9,431) ($3,184) ($7,055) 240V Fed. Min. HPWH (Interior Closet) 1992-2010 ($6,138) ($1,000) ($5,098) 240V Fed. Min. HPWH (Interior Closet, ducted) 1992-2010 ($9,505) ($2,836) ($7,271) 240V Fed. Min. HPWH + PV 1992-2010 ($2,300) $4,952 ($4,858) R-6 Ducts Pre-1978 $14,727 $18,685 $8,592
R-8 Ducts Pre-1978 $13,849 $17,990 $7,532
10% Duct Sealing Pre-1978 $7,280 $9,752 $4,294
R-13 Wall Insulation Pre-1978 $4,054 $6,898 $2,196
R-38 Attic Insulation Pre-1978 $5,461 $8,126 $1,668
R-49 Attic Insulation Pre-1978 $6,063 $8,978 $1,864
R-30 Raised Floor Insulation Pre-1978 ($1,776) $2,468 ($1,602) Cool Roof (0.20 Ref) Pre-1978 $2,123 $1,848 $851
Table 19. Electric Panel Upgrade Sensitivity for CZ 12 [1992-2010] Measure Standard Results Electric Panel Upgrade
On-Bill NPV LSC NPV On-Bill NPV LSC NPV
HPSH (Std Efficiency) ($2,151) $6,990 ($4,931) $4,210
240V Fed. Min. HPWH ($8,738) $3,536 ($11,624) $756
Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 30 Results
California Energy Codes & Standards | A statewide utility program 2024-04-25

3.3 Gas Pathways for Heat Pump Replacements
Many jurisdictions are exploring policy options to accelerate the decarbonization of existing homes. A recent Ninth Circuit Court ruling in California Rest. Ass'n v. City of Berkeley20 invalidated Berkeley’s ordinance banning the installation of gas infrastructure in new construction. The ruling stated that the ordinance effectively banned covered products and was preempted by the Energy Policy and Conservation Act (“EPCA”), 42 U.S.C. § 6297(c). Given the possible impacts of that ruling, the Reach Codes Team analyzed policy options targeting equipment replacements that allow for the installation of either electric or gas-fueled equipment. These packages include gas equipment combined with additional efficiency measures resulting in options that are reasonably energy or LSC cost equivalent, to the extent feasible.

For space heating, the heat pump path is a DFHP (existing furnace).. The gas pathway is a new air conditioner with the following list of efficiency upgrades:
x 400 cfm/ton system airflow (HERS verified).
x 0.35 W/cfm fan efficacy (HERS verified).
x Refrigerant charge verification (HERS verified).
x R-8 ducts, 5% leakage (HERS verified).
x R-49 (from R-30) attic insulation.
x Air sealing of the ceiling from 7 to 6.5 ACH50.

The two pathways are presented in Figure 14 comparing total LSC energy use relative to the existing home for the 1992-2010 vintage. In most climate zones, the DFHP (existing furnace) path results in higher energy savings, in the milder climates the air conditioner path saves marginally more energy. 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 air conditioner as long as the performance measures listed above are met. Note that in this analysis a DFHP (existing furnace) was used; however, a reach code could require a different heat pump measure for the heat pump path. This approach aligns with the CEC’s proposal for the 2025 Title 24 code cycle for heat pump alterations in single family homes (California Energy Commission, 2023).
20 California Rest. Ass'n v. City of Berkeley, 65 F.4th 1045 (9th Cir. 2023) amended by 89 F.4th 1094 (9th Cir. 2024).

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 31 Results
California Energy Codes & Standards | A statewide utility program 2024-04-25 Figure 14. Heat pump space heater path compared to the air conditioner path.

For water heating, the federal minimum HPWH case was used to develop the package. The HPWH was compared to a new gas storage water heater with a 50% solar thermal backup system.

The two pathways are presented in Figure 15 comparing total LSC energy use relative to the existing home for the 1992-2010 vintage. In all climate zones, the heat pump path results in higher energy savings than the gas path. A reach code that establishes requirements when a water heater is replaced could allow for either a HPWH to be installed or a gas water heater in combination with a solar thermal system that meets the solar fraction requirements listed above.

Figure 15. Heat pump water path compared to gas with solar thermal.

Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 32 Recommendations and Discussion
California Energy Codes & Standards | A statewide utility program 2024-04-25 4 Recommendations and Discussion
This analysis evaluated the feasibility and cost-effectiveness of retrofit measures in California existing homes built before 2010. The Statewide Reach Codes Team used both On-Bill and LSC-based LCC approaches to evaluate costeffectiveness and quantify the energy cost savings associated with energy efficiency measures compared to the incremental costs associated with the measures.

Conclusions and Discussion:

1. Envelope measures. Improving envelope performance is very cost-effective in many older homes. In addition to reducing utility costs these measures provide many other benefits such as improving occupant comfort and satisfaction and increasing a home’s ability to maintain temperatures during extreme weather events and power outages. Below is a discussion of the results of specific measures. a. Adding attic insulation is cost effective based on both LSC and On-Bill in many climate zones in homes with no more than R-19 existing attic insulation levels. Increasing attic insulation from R-30 to R-49 was still found to be cost-effective based on at least one metric in the colder and hotter climates of Climate Zone 10 (SDG&E territory only) through 16.
b. Insulating existing uninsulated walls is very cost-effective based on both metrics everywhere except Climate Zones 6 and 7 (in Climate Zone 8 it’s only cost-effective based on LSC). c. Adding R-19 or R-30 floor insulation is cost-effective based on LSC in the older two vintages (Pre-1978 and 1978-1991) in all climate zones except Climate Zones 6-10. d. Replacing old single pane windows with new high-performance windows has a very high cost and is typically not done for energy savings alone. However, energy savings are substantial and justify costeffectiveness of this measure based on at least one metric in Climate Zones 4, 8 through 12 (PG&E territory only), and 13 through 16.
e. At time of roof replacement, a cool roof with an aged solar reflectance of 0.25 was found to be costeffective in Climate Zones 4, 6 through 12 (PG&E territory only), and 13 through 15. When the roof deck is replaced during a roof replacement, adding a radiant barrier is low cost and provides substantial cooling energy savings to be cost-effective in almost all climate zones and homes.

2. Duct measures: Many older homes have old, leaky duct systems that should be replaced when they reach the end of life, typically 20-30 years. In this case, installing new ducts was found to be cost-effective based on at least one metric (both in most cases) everywhere except mild Climate Zone 7 and Climate Zones 5 and 6 in the 1978-1991 vintage. If duct systems still have remaining life they should be sealed and tested to meet 10% leakage or lower; however, duct upgrades alone were only found to be cost-effective for newer homes in Climate Zones 10 (SDG&E territory only), 11, and 13 through 16. Duct upgrades may be able to be coupled with other measures to reduce the cost.

3. Heat pump space heating: HPSHs were found to be LSC cost-effective in many cases. The DFHP (existing furnace) was LSC cost-effective everywhere except Climate Zone 15. The HPSH was LSC cost-effective everywhere except Climate Zones 8 and 15.
a. Challenges to On-Bill cost-effectiveness include higher first costs and higher first-year utility costs due to higher electricity tariffs relative to gas tariffs. SMUD and CPAU are two exceptions where first year utility costs are lower for heat pumps than for gas equipment. Table 11 shows the impact of utility rates on cost-effectiveness of HPSH where the standard and high efficiency HPSH and the HPSH + PV measures are cost-effective under SMUD but not PG&E. Even with higher first year utility bills, there were some cases that still proved On-Bill cost-effective including the DFHP with an existing furnace in the central valley and northern coastal PG&E territories, the ducted MSHP in the central valley as well as Climate Zone 14 in SDG&E territory, and the HPSH + PV measure in CZ 3-5 (PGE), 7-11, and 12 (SMUD) – 15.
b. The ductless MSHPs, evaluated for homes with existing ductless systems, were only found to be costeffective based on either metric in Climate Zones 1 and 16. Ductless MSHPs have a high incremental cost because it is a more sophisticated system than the base model of a wall furnace with a window AC unit. However, the ductless MSHP would provide greater comfort benefits if properly installed to Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 33 Recommendations and Discussion
California Energy Codes & Standards | A statewide utility program 2024-04-25 directly condition all habitable spaces (as is required under the VCHP compliance credit as evaluated in this study) which may be an incentive for a homeowner to upgrade their system. c. Higher efficiency equipment lowered utility costs in all cases and improved cost-effectiveness in many cases, particularly with a ducted MSHP.

4. Heat pump water heating: All the HPWH measures were LSC cost-effective in all climate zones. Most measures were not On-Bill cost-effective with the exception of the HPWH + PV which was cost-effective OnBill in CPAU, SMUD, and SDG&E territories in addition to Climate Zones 11, 13, 14, and 15. The HPWH measures share many of the same challenges as the HPSH measures to achieving cost-effectiveness including high first costs and utility rates and assumptions. Table 13 shows the impact of utility rates on costeffectiveness where some HPWH measures are cost-effective under SMUD utility rates but are not costeffective anywhere under PG&E rates in Climate Zone 12. a. Various HPWH locations were also explored, however there are some factors outside of costeffectiveness that should also be considered. i. HPWHs in the conditioned space can provide benefits such as free cooling during the summer, reduced tank losses, and shorter pipe lengths, and in some cases show improved cost-effectiveness over garage located HPWHs. However, there are various design considerations such as noise, comfort concerns, and condensate removal. Ducting the inlet and exhaust air resolves comfort concerns but adds costs and complexity. Split heat pump water heaters address these concerns, but currently there are limited products on the market and there is a cost premium relative to the packaged products. ii. Since HPWHs extract heat from the air and transfer it to water in the storage tank, they must have adequate ventilation to operate properly. Otherwise, the space cools down over time, impacting the HPWH operating efficiency. This is not a problem with garage installations but needs to be considered for water heaters located in interior or exterior closets. For the 2025 Title 24 code the CEC is proposing that all HPWH installations meet mandatory ventilation requirements (California Energy Commission, 2023).

5. The contractor surveys revealed overall higher heat pump costs than what has been found in previous analyses. This could be due to incentive availability raising demand for heat pumps and thereby increasing the price. This price increase may be temporary and may come down once the market stabilizes. There are also new initiatives to obtain current costs including the TECH Clean California program21 that publishes heat pump data and costs; however, at the time of this analysis, the TECH data did not contain incremental costs because it only had the heat pump costs but not the gas base case costs.

6. Table 18 shows how CARE rates and escalation rate assumptions will impact cost-effectiveness. a. Applying CARE rates in the IOU territories has the overall impact to increase utility cost savings for an all-electric building compared to a code compliant mixed fuel building, improving On-Bill costeffectiveness. This is due to the CARE discount on electricity being higher than that on gas. The reverse occurs with efficiency measures where lower utility rates reduce savings and subsequently reduce cost-effectiveness.
b. If gas tariffs are assumed to increase substantially over time, in-line with the escalation assumption from the 2025 LSC development, cost-effectiveness substantially improves for the heat pump measures over the 30-year analysis period and many cases become cost-effective that were not found to be cost-effective under the CPUC / 2022 TDV escalation scenario. There is much uncertainty surrounding future tariff structures as well as escalation values. While it’s clear that gas rates will increase, how much and how quickly is not known. Future electricity tariff structures are expected to evolve over time, and the CPUC has an active proceeding to adopt an income-graduated fixed charge that benefits low-income customers and supports electrification measures for all customers.22 The CPUC will decide in mid-2024 and the new rates are expected to be in place later that year or in 2025. 21 TECH Public Reporting Home Page (techcleanca.com)
22 https://www.cpuc.ca.gov/industries-and-topics/electrical-energy/electric-costs/demand-response-dr/demandflexibility-rulemaking Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 34 Recommendations and Discussion
California Energy Codes & Standards | A statewide utility program 2024-04-25 While the anticipated impact of this rate change is lower volumetric electricity rates, the rate design is not finalized. While lower volumetric electricity rates provide many benefits, it also will make building efficiency measures harder to justify as cost-effective due to lower utility bill cost savings.

7. Under NBT, utility cost savings for PV are substantially less than what they were under prior net energy metering rules (NEM 2.0); however, savings are sufficient to be On-Bill cost-effective in all climate zones except Climate Zones 1 through 3 and 5 through 6.
a. Combining a heat pump with PV allows the additional electricity required by the heat pump to be offset by the PV system while also increasing on-site utilization of PV generation rather than exporting the electricity back to the grid at a low rate.
b. While not evaluated in this study, coupling PV with battery systems can be very advantageous under NBT increasing utility cost savings because of improved on-site utilization of PV generation and fewer exports to the grid.

Recommendations:

1. There are various approaches for jurisdictions who are interested in reach codes for existing buildings. Some potential approaches are listed below along with key considerations. a. Prescriptive measures: Non-preempted measures that are found to be cost-effective may be prescriptively required in a reach code. One example of this type or ordinance is a cool roof requirement at time of roof replacement. Another example is requiring specific cost-effective measures for larger remodels, such as high-performance windows when new windows are installed or duct sealing and testing where ducts are in unconditioned space. b. Replacement equipment: This flavor of reach code sets certain requirements at time of equipment replacement. This study evaluated space heating and water heating equipment. Where a heat pump measure was found to be cost-effective based on either LSC or On-Bill, this may serve as the basis of a reach code given the following considerations.
i. Where reach codes reduce energy usage and are not just fuel switching, cost-effectiveness calculations are required and must be based on equipment that does not exceed the federal minimum efficiency requirements.
ii. Where reach codes are established using cost-effectiveness based on LSC, utility bill impacts and the owner’s first cost should also be reviewed and considered. iii. A gas path should also be prescriptively allowed to safely satisfy federal preemption requirements considering the CRA v. Berkeley case.23 Additional requirements may apply to the gas path, as described in Section 3.3, as long as the paths are reasonably energy or cost equivalent.
c. “Flexible Path”, minimum energy savings target: This flexible approach establishes a target for required energy savings based on a measure or a set of measures that were found to be cost-effective based on either LSC or On-Bill. A points menu compares various potential upgrades ranging from efficiency, PV, and fuel substitution measures, based on site or source energy savings. The applicant must select upgrades that individually or in combination meet the minimum energy savings target. The measures used to set the target should be non-preempted measures.

2. Equipment replacement ordinances should consider appropriate exceptions for scenarios where it will be challenging to meet the requirements, such as location of the HPWH, total project cost limitations, or the need for service panel upgrades that wouldn’t have been required as part of the proposed scope of work in absence of the reach code.

3. Consider extending relevant proposals made by the CEC for the 2025 Title 24 code (California Energy Commission, 2023) in ordinances that apply under the 2022 Title 24 code, such as the following:
a. Mandatory ventilation requirements for HPWH installations (Section 110.3(c)7). 23 https://www.publichealthlawcenter.org/sites/default/files/2024-01/CRA-v-Berkeley-Ninth-Circuit-Opinion-Jan2024.pdf Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 35 Recommendations and Discussion
California Energy Codes & Standards | A statewide utility program 2024-04-25 b. Requirement for HERS verified refrigerant charge verification for heat pumps in all climate zones (Table 150.1-A24).

4. When evaluating reach code strategies, the Reach Codes Team recommends that jurisdictions consider combined benefits of energy efficiency alongside electrification. Efficiency and electrification have symbiotic benefits and are both critical for decarbonization of buildings. As demand on the electric grid is increased through electrification, efficiency can reduce the negative impacts of additional electricity demand on the grid, reducing the need for increased generation and storage capacity, as well as the need to upgrade upstream transmission and distribution equipment.

5. Education and training can play a critical role in ensuring that heat pumps are installed, commissioned, and controlled properly to mitigate grid impacts and maximize occupant satisfaction. Below are select recommended strategies.
a. The Quality Residential HVAC Services Program25 is an incentive program to train California contractors in providing quality installation and maintenance while advancing energy-efficient technologies in the residential HVAC industry. Jurisdictions can market this to local contractors to increase the penetration of contractors skilled in heat pump design and installation. b. Educate residents and contractors of available incentives, tax credits, and financing opportunities. c. Educate contractors on code requirements. Energy Code Ace provides free tools, trainings, and resource to help Californians comply with the energy code. Contractors can access interactive compliance forms, fact sheets, and live and recorded trainings, among other things, on the website:
https://energycodeace.com/. Jurisdictions can reach out to Energy Code Ace directly to discuss offerings.

6. Health and safety
a. Combustion Appliance Safety and Indoor Air Quality: Implementation of some of the recommended measures will affect the pressure balance of the home which can subsequently impact the safe operation of existing combustion appliances as well as indoor air quality. Buildings with older gas appliances can present serious health and safety problems which may not be addressed in a remodel if the appliances are not being replaced. It is recommended that the building department require inspection and testing of all combustion appliances located within the pressure boundary of the building after completion of retrofit work that involves air sealing or insulation measures. b. Jurisdictions may consider requiring mechanical ventilation in homes where air sealing has been conducted. In older buildings, outdoor air is typically introduced through leaks in the building envelope.

After air sealing a building, it may be necessary to forcefully bring in fresh outdoor air using supply and/or exhaust fans to minimize potential issues associated with indoor air quality. 24 This requirement does not show up in the Express Terms for alterations in Section 150.2(b)1F, but the Statewide Reach Codes Team expects that it will be added to the next release of the proposed code language in the 45-day language as it aligns with the proposal made by the Codes and Standards Enhancement Team (Statewide CASE Team, 2023).
25 https://qualityhvac.frontierenergy.com/
Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 36 References
California Energy Codes & Standards | A statewide utility program 2024-04-25 5 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. (2022b). 2022 Reference Appendices for the 202 Building Energy Efficiency Standards.

CEC-400-2022-010-AP. Retrieved from https://www.energy.ca.gov/sites/default/files/2022-08/CEC-400- 2022-010-AP.pdf
California Energy Commission. (2022c, Feb). 2022 Single-Family Residential Alternative Calculation Method Reference Manual. CEC-400-2022-008-CMF-REV. Retrieved from https://www.energy.ca.gov/publications/2022/2022- single-family-residential-alternative-calculation-method-reference-manual 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=88051 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-affairsdivision/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. (2022). Preliminary Analysis Technical Support Document: Energy Efficiency Program for Consumer Products and Commercial and Industrial Equipment. Retrieved from https://www.regulations.gov/document/EERE-2017-BT-STD-0019-0018 Department of Energy. (2023). Technical Support Document: Energy Efficiency Program for Consumer Products and Commercial and Industrial Equipment: Room Air Conditioners. Retrieved from https://www.regulations.gov/document/EERE-2014-BT-STD-0059-0053 E-CFR. (2020). https://www.ecfr.gov/cgibin/retrieveECFR?gp=&SID=8de751f141aaa1c1c9833b36156faf67&mc=true&n=pt10.3.431&r=PART&ty=HTM L#se10.3.431_197. Retrieved from Electronic Code of Federal Regulations: https://www.ecfr.gov/cgibin/retrieveECFR?gp=&SID=8de751f141aaa1c1c9833b36156faf67&mc=true&n=pt10.3.431&r=PART&ty=HTM L#se10.3.431_197
Statewide CASE Team. (2023). Residential HVAC Performance. Codes and Standards Enhancement (CASE) Initiative 2025 California Energy Code. Prepared by Frontier Energy. Retrieved from https://title24stakeholders.com/wp-content/uploads/2023/11/Revised_2025_T24_Final-CASE-Report-RESHVAC-Performance.pdf Statewide Reach Codes. (2023). Cost Effectiveness Explorer. Retrieved from Cost Effectiveness Explorer:
https://explorer.localenergycodes.com/
Statewide Reach Codes Team. (2021). 2019 Cost-Effectiveness Study: Existing Single Family Residential Buidling Upgrades. Retrieved from https://localenergycodes.com/content/resources Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 37 Appendices
California Energy Codes & Standards | A statewide utility program 2024-04-25 6 Appendices

6.1 Map of California Climate Zones
Climate zone geographical boundaries are depicted in Figure 16. The map in Figure 16 along with a zip-code search directory is available at: https://ww2.energy.ca.gov/maps/renewable/building_climate_zones.html Figure 16. Map of California climate zones.

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6.2 Utility Rate Schedules
The Reach Codes Team used the CA IOU and POU rate tariffs detailed below to determine the On-Bill savings for each package. The California Climate Credit was applied for both electricity and natural gas service for the IOUs using the 2023 credits shows below.26 The credits were applied to reduce the total calculated annual bill, including any fixed fees or minimum bill amounts.

Electricity rates reflect the most recently approved tariffs. Monthly gas rates were estimated based on recent gas rates (November 2023) and a curve to reflect how natural gas prices fluctuate with seasonal supply and demand. The seasonal curve was estimated from monthly residential tariffs between 2014 and 2023 (between 2017 and 2023 for CPAU). 12-month curves were created from monthly gas rates for each of the ten years (Seven years for CPAU).

These annual curves were then averaged to arrive at an average normalized annual curve. This was conducted separately for baseline and excess energy rates. Costs used in this analysis were then derived by establishing the most recent baseline and excess rate from the latest tariff as a reference point (November 2023), and then using the normalized curve to estimate the cost for the remaining months relative to the reference point rate. 26 https://www.cpuc.ca.gov/industries-and-topics/natural-gas/greenhouse-gas-cap-and-trade-program/californiaclimate-credit Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 39 Appendices
California Energy Codes & Standards | A statewide utility program 2024-04-25

6.2.1 Pacific Gas & Electric
The following pages provide details on the PG&E electricity and natural gas tariffs applied in this study. Table 20 describes the baseline territories that were assumed for each climate zone. A net surplus compensation rate of $0.07051/ kWh was applied to any net annual electricity generation based on a one-year average of the rates between December 2022 and November 2023.

Table 20. 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 21.

These rates are based on applying a normalization curve to the November 2023 tariff based on ten years of historical gas data. Corresponding CARE rates reflect the 20 percent discount per the GL-1 tariff.

Table 21. PG&E Monthly Gas Rate ($/therm)
Month Total Charge
Baseline Excess
January $2.05 $2.43
February $2.08 $2.46
March $1.92 $2.31
April $1.80 $2.20
May $1.77 $2.18
June $1.78 $2.18
July $1.80 $2.20
August $1.85 $2.26
September $1.92 $2.33
October $1.99 $2.40
November $2.06 $2.46
December $2.05 $2.44
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6.2.2 Southern California Edison
The following pages provide details on the SCE electricity tariffs applied in this study. Table 22 describes the baseline territories that were assumed for each climate zone. A net surplus compensation rate of $ 0.06030/ kWh was applied to any net annual electricity generation based on a one-year average of the rates between December 2022 and November 2023
Table 22: 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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6.2.3 Southern California Gas
Following are the SoCalGas natural gas tariffs applied in this study. Table 23 describes the baseline territories that were assumed for each climate zone.

Table 23. 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 was applied on a monthly basis according to the rates shown in Table 24.

These rates are based on applying a normalization curve to the November 2023 tariff based on ten years of historical gas data. Long-term historical natural gas rate data was only available for SoCalGas’ procurement charges.27 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 2023 rates. CARE rates reflect the 20 percent discount per the GR tariff.

Table 24. SoCalGas Monthly Gas Rate ($/therm)
Month Procurement
Charge
Transportation Charge Total Charge
Baseline Excess Baseline Excess
January $0.72 $0.86 $1.31 $1.92 $2.36
February $0.50 $0.86 $1.31 $1.57 $2.02
March $0.44 $0.86 $1.31 $1.48 $1.93
April $0.39 $0.86 $1.31 $1.39 $1.84
May $0.41 $0.86 $1.31 $1.43 $1.87
June $0.46 $0.86 $1.31 $1.49 $1.93
July $0.47 $0.86 $1.31 $1.51 $1.96
August $0.51 $0.86 $1.31 $1.58 $2.03
September $0.46 $0.86 $1.31 $1.52 $1.96
October $0.45 $0.86 $1.31 $1.48 $1.92
November $0.48 $0.86 $1.31 $1.54 $1.99
December $0.57 $0.86 $1.31 $1.63 $2.08
27 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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6.2.4 San Diego Gas & Electric
Following are the SDG&E electricity and natural gas tariffs applied in this study. Table 25 describes the baseline territories that were assumed for each climate zone. A net surplus compensation rate of $0.04542/ kWh was applied to any net annual electricity generation based on a one-year average of the rates between December 2022 and November 2023.

Table 25. 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

26. These rates are based on applying a normalization curve to the November 2023 tariff based on ten years of historical gas data. CARE rates reflect the 20 percent discount per the G-CARE tariff.

Table 26. SDG&E Monthly Gas Rate ($/therm)
Month Total Charge
Baseline Excess
January $2.34 $2.63
February $2.28 $2.57
March $2.21 $2.51
April $2.14 $2.45
May $2.18 $2.48
June $2.23 $2.55
July $2.26 $2.57
August $2.32 $2.62
September $2.26 $2.59
October $2.21 $2.55
November $2.24 $2.57
December $2.38 $2.70
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6.2.5 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 27. These rates are based on applying a normalization curve to the October 2023 tariff based on seven years of historical gas data. The monthly service charge applied was $14.01 per month per the November 2023 G-1 tariff.

Table 27. CPAU Monthly Gas Rate ($/therm)
Month G1 Volumetric
Total Baseline
G1 Volumetric
Total Excess
January $1.83532 $3.35639
February $1.38055 $2.59947
March $1.32506 $2.47695
April $1.29680 $2.44038
May $1.29511 $2.43804
June $1.32034 $2.45406
July $1.35688 $2.61519
August $1.40696 $2.67944
September $1.42130 $2.70301
October $1.42310 $2.48300
November $1.46286 $2.45547
December $1.62415 $2.62128
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6.2.6 Sacramento Municipal Utilities District (Electric Only) Following are the SMUD electricity tariffs applied in this study. The rates effective January 2023 were used.

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6.2.7 Fuel Escalation Assumptions
The average annual escalation rates in Table 28 were used in this study. These 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 29 presents the average annual escalation rates used in the utility rate escalation sensitivity analysis shown in Section 3.2.4. Rates were applied for the same 30-year period and are based on the escalation rate assumptions within the 2025 LSC factors from 2027 through 2053.28 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 years 2024, 2025, and 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.

Table 28: Real Utility Rate Escalation Rate Assumptions, CPUC En Banc and 2022 TDV Basis
28https://www.energy.ca.gov/files/2025-energy-code-hourly-factors. Actual escalation factors were provided by consultants E3.

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

PG&E SCE SDG&E
2024 4.6% 1.8% 1.6% 2.8%
2025 4.6% 1.8% 1.6% 2.8%
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%
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California Energy Codes & Standards | A statewide utility program 2024-04-25 Table 29: 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)
2024 4.6% 2.1%
2025 4.6% 2.1%
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%
Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 69 Appendices
California Energy Codes & Standards | A statewide utility program 2024-04-25 Get In Touch
The adoption of reach codes can differentiate jurisdictions as efficiency leaders and help accelerate the adoption of new equipment, technologies, code compliance, and energy savings strategies.

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Our experts develop robust toolkits as well as provide specific technical assistance to local jurisdictions (cities and counties) considering adopting energy reach codes. These include Cost-effectiveness research and analysis, model ordinance language and other code development and implementation tools, and specific technical assistance throughout the code adoption process.

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Cost-Effectiveness Analysis: Existing Single Family Building Upgrades 70 Appendices
California Energy Codes & Standards | A statewide utility program 2024-04-25 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

ATTACHMENT C
2025 Energy Code: Existing Single Family Building Upgrades 1 2025/08/15
Table 1 Summary of Revisions
Date Description Reference (page or section)
8/15/2025 Original Release N/A
Legal Notice
This report was prepared by
Pacific Gas and Electric Company
and funded by the California utility
customers under the auspices of
the California Public Utilities
Commission.

Copyright 2025, Pacific Gas and
Electric Company. All rights
reserved, except that this
document may be used, copied,
and distributed without
modification.

Neither PG&E nor any of its
employees makes any warranty,
express or implied; or assumes
any legal liability or responsibility
for the accuracy, completeness or
usefulness of any data,
information, method, product,
policy or process disclosed in this
document; or represents that its
use will not infringe any privatelyowned rights including, but not limited to, patents, trademarks or
copyrights.
2025 Energy Code: Existing Single Family Building Upgrades 2 2025/08/15
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 1 2025/08/15
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 2 2025/08/15
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.
2025 Energy Code: Existing Single Family Building Upgrades 3 2025/08/15
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 costeffectiveness analysis for this measure is presented in Section 4.

The 3 kW PV measure from the 2022 study is revised here with an updated costeffectiveness 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].
2025 Energy Code: Existing Single Family Building Upgrades 4 2025/08/15
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)
2025 Energy Code: Existing Single Family Building Upgrades 5 2025/08/15
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)
2025 Energy Code: Existing Single Family Building Upgrades 6 2025/08/15
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)
2025 Energy Code: Existing Single Family Building Upgrades 7 2025/08/15
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 8 2025/08/15
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 9 2025/08/15
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)
2025 Energy Code: Existing Single Family Building Upgrades 10 2025/08/15
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 11 2025/08/15
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 12 2025/08/15
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 13 2025/08/15
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 14 2025/08/15
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 15 2025/08/15
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 16 2025/08/15
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 17 2025/08/15
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 18 2025/08/15
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 19 2025/08/15
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 20 2025/08/15
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 21 2025/08/15
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 22 2025/08/15
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/cpucwebsite/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/cgibin/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/cgibin/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_CASEReport-_MF-DHW-Final-1.pdf Statewide CASE Team. (2023). Residential HVAC PErformance. Retrieved from https://title24stakeholders.com/wpcontent/uploads/2023/11/Revised_2025_T24_Final-CASE-Report-RES-HVACPerformance.pdf 2025 Energy Code: Existing Single Family Building Upgrades 23 2025/08/15
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 24 2025/08/15
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Revision: 1.0
Last modified: 2025/08/15

ATTACHMENT D
Green Building Chapter Summary / FAQs
What are Green Building Codes:

The state sets certain minimum building code standards every 3 years, which local jurisdictions must adopt and enforce. The Town Council adopts these codes by reference and they are generally contained in Fairfax Municipal Code. The 2025 state building code update will go into effect on January 1, 2026.

Green building codes are a certain type of building code that are designed to reduce environmental impacts. These requirements encourage practices such as:
• Using less energy and water,
• Reducing reliance on fossil fuels,
• Recycling construction waste,
• Improving indoor air quality, and
• Supporting healthier, more resilient communities.

California’s statewide green building code, known as CALGreen (Title 24, Part 11), was first adopted in 2010 and is updated every three years.

In addition to “green” building codes, “reach” codes, may be adopted locally to go beyond the state regulations to reflect local priorities, such as wildfire risk, seismic safety, or climate action goals.

Tier 1 of the Green Building Code
In 2019 and 2022, Fairfax has adopted Tier 1 of the Green Building Code. Tier 1 are voluntary measures that the state publishes that jurisdictions can opt-into and enforce.

They go above and beyond at encouraging electrification, efficiency, and resilience.

AB 130 – A pause on all Green Building Code Updates Until 2031 Until recently, local jurisdictions have been authorized to adopt local amendments to the state building codes based on localized conditions and priorities. However, effective October 1, 2025, AB 130 pauses local jurisdictions’ ability to modify building codes (including green building and reach codes) in order to encourage housing development.

What can the town still do given AB 130?
As referenced in the staff report, there are a few exceptions to AB 130 like if jurisdictions have had similar codes in place before the October 1st deadline. Legal review has determined that adopting Tier 1 of the 2025 Code is substantially similar to the adoption of Tier 1 completed in 2022 and Town is implementing that exception to the assembly bill.

Flexible Compliance Options:

In 2022, Fairfax adopted local green building standards and reach codes including Marin County’s Flexible Compliance Pathway (FlexPath) for remodels. FlexPath allows projects to achieve a target score by selecting from a menu of energy efficiency and electrification measures, giving builders and homeowners flexibility to implement measures that best suit their project.

Feedback from the building community and building department staff since adoption in 2022 indicates that the Flex Path is reasonable to comply with and to enforce. In a recent meeting, Marin Builders Association expressed appreciation for the flexibility the policy offers, valuing that it lets homeowners and builders choose what measures make the most sense for the home, as opposed to prescriptive requirements that may not make sense within the project scope. Flex Path offers cost-effective options that contribute to Fairfax’s Town Council adopted climate goals.

All remodel projects over 200 square feet are required to go through the Flexible Compliance Pathway, EXCEPT certain hardship and infeasibility variables such as:
- Compliance disproportionate to overall project cost;
- Strict compliance with the standards would create or maintain a hazardous condition(s) and present a life safety risk to the occupants; - Conflicts with State standards;
- Measures impair a listed historic structure.

What’s in the Flex Path Code:

The Flex Path menu contains a mix of energy efficiency and electrification measures.

Generally, the electrification measures such as heat pump water heater or heat pump HVAC conversion from gas have a high point value and can be a simple way to achieve the target score. The policy has proven to be an effective tool to encourage home appliance electrification, in conjunction with the Electrify Marin rebate program. Bay Area Air District zero-NOx appliance rules are scheduled to ban the sale of gas water heaters and furnaces in 2027 and 2029, respectively, so the Flex Path’s encouragement of heat pumps makes Marin homeowners and building professionals better prepared for the transition.

What’s in the 2025 Tier 1 Code:
- EV-ready wiring for single-family homes
- Electric Vehicle Supply Equipment (EVSE) requirements for multifamily and nonresidential buildings
- Embodied carbon compliance for large projects
- Bicycle parking (multifamily & nonresidential)
- Heat pump and photovoltaic baselines in the energy code Comparison to other Marin Jurisdictions
Jurisdiction
2022
CALGreen
Tier 1
Adopted?
Flexible
Compliance
Pathway adopted
pre 2025?
Planning to
adopt 2025 Tier
1?
Readopt
FlexPath?
Unincorporated
Marin Yes Yes
Yes, only nonenergy and EV
measures
Yes
Corte Madera
No, just some
EV reach
codes
Yes No Yes
San Anselmo Yes Yes No Yes
Larkspur Yes No Yes —
Mill Valley Yes No Yes Yes
Novato Yes No Yes —
San Rafael No Yes No Yes
Sausalito No No In conversation —
Tiburon Yes Yes but never
enforced Yes Yes