CRC · California Residential Code

When alterations trigger Title 24 Part 6 compliance

Additions to buildings must follow the California Energy Code (Part 6). Alterations — especially replacing cooling equipment — can trigger energy‑efficiency upgrades and field testing when Appendix A4 applies locally; always confirm whether your city has adopted Appendix A4 before assuming its rules apply.

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Last reviewed: July 6, 2026

What the code requires — plain English

  • Additions to existing buildings must follow the California Energy Code (Title 24, Part 6): § 1104.1 requires that additions comply with the applicable provisions of Part 6.
  • For alterations to existing residential buildings, Appendix A4 (voluntary CALGreen residential measures) requires certain energy-efficiency compliance when specific systems are altered — specifically § A4.204.1 and its subsections set rules for altered space‑conditioning systems and other altered components. (Appendix A4 is voluntary unless a local jurisdiction adopts it.)

The single most important rule: additions must meet Part 6; alterations may trigger Part 6 requirements when they replace or substantially change energy‑related systems — check § 1104.1 and § A4.204.1 and confirm whether Appendix A4 is adopted locally.

Requirements in detail

Scope and how to decide

  • Work type: Distinguish addition, alteration, repair, and replacement. Additions automatically require Part 6 compliance per § 1104.1.
  • Alterations to residential buildings trigger the Appendix A4 rules when an alteration touches the systems listed in § A4.204.1 (see A4.204.1.1 for space‑conditioning). Whether those A4 rules apply depends on local adoption — Appendix A4 is voluntary unless a jurisdiction adopts it as mandatory.
  • Many Part 6 compliance details for alterations are found in the Energy Code sections referenced by the Appendix (for example, Sections 150.0 and 150.2 for altered components and additions).

Key decision dimensions (quick reference)

Decision dimension Values / thresholds you check What it means for compliance Code Reference
Type of work Addition vs Alteration / Repair Additions must comply with Part 6. Alterations may trigger Part 6 or Appendix A4 requirements depending on scope and local adoption. § 1104.1
Altered HVAC: cooling equipment Installation or replacement of an air conditioner (single‑family) in CZ 1–14, 16 Requires compliance with A4.204.1.1 (either heat pump primary or specific duct & airflow/fan requirements). § A4.204.1.1
Duct leakage (when option b chosen) ≤ 5% of system air handler airflow Must be field verified per Reference Residential Appendix RA3.1.4.3.1. § A4.204.1.1.b.ii (RA3.1 ref)
Return airflow per ton ≥ 400 CFM per ton (all control modes) Confirmed by field verification and diagnostic testing per RA3.3. § A4.204.1.1.b.iii
Duct insulation R‑8 for ducts located in unconditioned space (option b) Install or upgrade to meet this thermal requirement. § A4.204.1.1.b.i
Additions size exceptions ≤ 300 sq ft or ≤ 1,000 sq ft (exceptions for some requirements) Certain prescriptive exceptions to Part 6 apply to small additions (see Section 150.2 exceptions). § 150.2 (additions/alterations rules & exceptions)
Appendix A4 status Voluntary unless locally adopted A4 provisions (including A4.204.1) are not automatically statewide mandatory; local adoption + CEC approval is required to make them mandatory. A4.201.1 (voluntary/ local adoption)

How A4.204.1 works in practice

  • A4.204.1 establishes that alterations to existing residential buildings must meet A4.204.1.1 and A4.204.1.2; those detail required measures for altered space‑conditioning systems and other altered equipment. If a jurisdiction has adopted Appendix A4, then these requirements become enforceable locally.
  • For single‑family dwellings that are undergoing replacement/installation of an air conditioner in certain climate zones, A4.204.1.1 sets two compliance paths (a or b): make a heat pump primary heating source, or meet specific duct, leakage, airflow, and fan‑efficacy metrics and field‑test them.

Exceptions & special cases

  • Appendix A4 is voluntary statewide; its requirements apply only where a local jurisdiction has formally adopted the Appendix as mandatory. Always confirm local adoption before treating A4 as binding.
  • The statewide Energy Code contains explicit exceptions for small additions (for example, some roofing rules for additions of 300 sq ft or less) and other limited exemptions listed in Section 150.2; those exceptions can reduce the scope of required upgrades for small projects.
  • If heating/cooling for an addition is provided by extending the existing system, the Energy Code may not require the existing equipment to be upgraded in some cases (see exceptions in Section 150.2(a)). Verify which 150.2 exceptions apply to your work.

Common mistakes

  • Treating Appendix A4 as automatically mandatory. In many places A4 is voluntary; always check local municipal code or ask the enforcing agency.
  • Assuming every minor equipment swap triggers the whole of Part 6. Only specific replacements/alterations (or additions) trigger required Part 6 measures; read the specific triggers (e.g., replacement of an air conditioner under A4.204.1.1) and Part 6 alteration rules in Section 150.2.
  • Missing the required field verification/testing standards (duct leakage ≤ 5%, ≥ 400 CFM/ton, fan efficacy ≤ 0.35 W/CFM) and the referenced test procedures (Reference Residential Appendix RA3.*). Those are mandatory when the A4 option demands them.
  • Forgetting climate‑zone limits (A4.204.1.1 specifically targets Climate Zones 1–14 and 16). Check climate zone before applying A4.204.1.1.

Worked example — concrete scenario

Scenario: You are replacing a 3‑ton (nominal) air conditioner on a single‑family home in Climate Zone 10 and your city has adopted Appendix A4.

  1. A4 applies because your jurisdiction adopted Appendix A4 (confirm enabling ordinance).
  2. Under § A4.204.1.1, you may choose option (a) or (b). If you choose option (b) (keep an air conditioner and meet requirements), you must:
    • Insulate ducts in unconditioned spaces to R‑8.
    • Achieve duct leakage ≤ 5% of system air handler airflow. For a 3‑ton system assume required airflow = 3 tons × 400 CFM/ton = 1200 CFM; 5% of 1200 = 60 CFM maximum leakage allowed (field‑verified).
    • Demonstrate return airflow ≥ 400 CFM per ton in every control mode (so ≥ 1200 CFM for this 3‑ton unit) and fan efficacy ≤ 0.35 W/CFM; these must be confirmed via the field verification procedures in the Reference Residential Appendix RA3.3.
  3. If testing shows duct leakage is 90 CFM (7.5%), the system fails A4.204.1.1.b.ii and must be tightened/reworked (or you must select option a, replacing with a heat pump primary system).

Related provisions (quick list)

  • § 1104.1 — Additions must comply with the California Energy Code (Part 6).
  • § A4.204.1 / A4.204.1.1 — Appendix A4 rules for alterations to existing residential buildings and altered space‑conditioning systems.
  • § 150.2 — Energy efficiency standards for additions and alterations to existing single‑family residential buildings (prescriptive & exceptions).
  • Reference Residential Appendix RA3.1 / RA3.3 — Field verification and diagnostic testing procedures referenced by A4.204.1.1 for duct leakage, airflow and fan efficacy.
  • A4.201.1 — Appendix A4 is voluntary unless locally adopted; process for local adoption and CEC approval.

If you want, I can:

  • Check whether your city has adopted Appendix A4, or
  • Walk through the specific compliance steps for a planned alteration (measure list, test forms, certificate language).

Code references

Grounded in the retrieved California Residential Code — click a citation to read the verbatim passage:

  • CRC § 204.1 High relevance — show source text
    1. Lighting for industrial sites, including but not limited to, rail yards, maritime shipyards and docks, piers and marinas, chemical and petroleum processing plants, and aviation facilities.
    2. Lighting of tunnels, bridges, stairs, wheelchair elevator lifts for American with Disabilities Act (ADA) compliance, and ramps that are not parking garage ramps.
    3. In theme parks: outdoor lighting only for themes and special effects.
    4. Lighting for outdoor theatrical and other outdoor live performances, provided that these lighting systems are additions to area lighting systems and are controlled by a multi-scene or theatrical cross-fade control station accessible only to authorized operators.
    5. Outdoor lighting systems for qualified historical buildings, as defined in the California Historical Building Code (Title 24, Part 8), if they consist solely of historical lighting components or replicas of historical lighting components. If lighting systems for qualified historical buildings contain some historical lighting components or replicas of historical components, combined with other lighting components, only those historical or historical replica components are exempt. All other outdoor lighting systems for qualified historical buildings shall not be exempted.

    APPENDIX A4-10 2025 CALIFORNIA GREEN BUILDING STANDARDS CODE

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    APPENDIX A4 — RESIDENTIAL VOLUNTARY MEASURES

    SECTION A4.204 — REQUIREMENTS FOR ALTERATIONS TO EXISTING BUILDINGS

    A4.204.1 Energy efficiency. Alterations to existing residential buildings shall comply with Sections A4.204.1.1 and A4.204.1.2.

    A4.204.1.1 Altered space-conditioning system serving existing single-family dwelling units – mechanical cooling. When a space-conditioning system serving an existing single-family dwelling unit is altered in Climate Zones 1 through 14 and 16 by installation or replacement of an air conditioner, the altered system shall comply with either a or b below in addition to the requirements for installation specified by Title 24, Part 6, Sections 150.2(b)1E and 150.2(b)1F: a. A heat pump shall be the primary heating source and sized according to the system selection requirements specified by Title 24, Part 6 of Section 150.0(h)5. Supplemental heating may be provided by an existing gas furnace or existing electric resistance heating; or b. An air conditioner shall meet the following requirements: i. R-8 duct insulation for ducts located in unconditioned space; and ii. The duct system measured air leakage shall be equal to or less than 5 percent of the system air handler airflow as confirmed through field verification and diagnostic testing, per the requirements in Title 24, Part 6, Reference Residential Appendix Section RA3.1.4.3.1; and iii. Demonstrate, in every control mode, airflow greater than or equal to 400 CFM per ton of nominal cooling capacity through the return grilles, and an air-handling unit fan efficacy less than or equal to 0.35 W/CFM. The airflow rate and fan efficacy requirements in this section shall be confirmed through field verification and diagnostic testing, following the procedures outlined in Title 24, Part 6, Reference Residential Appendix RA3.3; and iv.

  • CRC § 100.1 Medium relevance — show source text

    (d) Track lighting supplementary overcurrent protection panel. A Track Lighting Supplementary Overcurrent Protection Panel shall be used only for line-voltage track lighting and shall be recognized for compliance with Part 6 only if it meets all of the following requirements:

    1. Shall be listed as defined in Section 100.1; and

    2. Shall have a permanently installed label that is prominently located stating the following: “NOTICE: This Panel for Track Lighting Energy Code Compliance Only.” The overcurrent protection devices in this panel shall only be replaced with the same or lower amperage. No other overcurrent protective device shall be added to this panel. Adding to, or replacement of, existing overcurrent protective device(s) with higher continuous ampere rating will void the panel listing and require resubmittal of compliance documentation to the enforcement agency responsible for compliance with the California Title 24, Part 6 Building Energy Efficiency Standards.

    SECTION 110.10—MANDATORY REQUIREMENTS FOR SOLAR READINESS

    (a) Covered occupancies.

    1. Single-family residences. Single-family residences located in subdivisions with ten or more single-family residences and where the application for a tentative subdivision map for the residences has been deemed complete or approved by the enforcement agency, which do not have a photovoltaic system installed, shall comply with the requirements of Sections 110.10(b) through 110.10(e)

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    ALL OCCUPANCIES—MANDATORY REQUIREMENTS FOR THE MANUFACTURE, CONSTRUCTION AND INSTALLATION OF SYSTEMS, EQUIPMENT AND BUILDING COMPONENTS

    1. Low-rise multifamily buildings. Low-rise multifamily buildings that do not have a photovoltaic system installed shall comply with the requirements of Sections 110.10(b) through 110.10(d).
    2. Hotel/motel occupancies and high-rise multifamily buildings. Hotel/motel occupancies and high-rise multifamily buildings with ten habitable stories or fewer, that do not have a photovoltaic system installed, shall comply with the requirements of Sections 110.10(b) through 110.10(d).
    3. Nonresidential buildings. Nonresidential buildings with three habitable stories or fewer, other than I-2 and I-2.1 buildings, that do not have a photovoltaic system installed, shall comply with the requirements of Sections 110.10(b) through 110.10(d).

    (b) Solar zone.

    1. Minimum solar zone area. The solar zone shall have a minimum total area as described below. The solar zone shall comply with access, pathway, smoke ventilation and spacing requirements as specified in Title 24, Part 9 or other Parts of Title 24 or in any requirements adopted by a local jurisdiction. The solar zone total area shall be comprised of areas that have no dimension less than five feet and are no less than 80 square feet each for buildings with roof areas less than or equal to 10,000 square feet or no less than 160 square feet each for buildings with roof areas greater than 10,000 square feet. A. Single-family residences. The solar zone shall be located on the roof or overhang of the building and have a total area no less than 250 square feet. Exception 1 to Section 110.10(b)1A: Single-family residences with a permanently installed domestic solar waterheating system meeting the installation criteria specified in the Reference Residential Appendix RA4 and with a minimum solar savings fraction of 0.50.
  • CRC § 62.2 Medium relevance — show source text

    b. Replacement ventilation fans. Whole-dwelling unit replacement ventilation fans shall be rated for airflow and sound in accordance with the requirements of ASHRAE 62.2 Sections 7.1 and 7.3. Additionally, when conformance to a specified whole-dwelling unit airflow rate is required for compliance, the replacement fans shall be rated at no less than the airflow rate required for compliance. c. Air filters. If the air filtration device for a whole-dwelling unit ventilation system is altered or replaced, then one of the following Subsections 1 or 2 shall be used for compliance as applicable.

    1. Dwellings that were required by a previous building permit to comply with the ventilation system air filtration requirements in Section 150.0(m)12 shall comply with the air filtration requirements in Section 150.0(m)12.

    2. Dwellings that were not required by a previous building permit to comply with the ventilation system air filtration requirements in Section 150.0(m)12 shall not be required to comply with the air filtration requirements specified in Section 150.0(m)12.

    ii. Local mechanical exhaust.

    a. Bathroom local mechanical exhaust. Altered bathroom local mechanical exhaust systems shall comply with the applicable requirements specified in Section 150.0(o)1G. b. Kitchen local mechanical exhaust. If the kitchen local ventilation fan is altered or replaced, then one of the following Subsections 1, 2 or 3 shall be used for compliance as applicable.

    1. Dwellings that were required by a previous building permit to comply with the kitchen local exhaust requirements in Section 150.0(o)1G shall meet or exceed the applicable airflow or capture efficiency requirements in Section 150.0(o)1G.
    2. Dwellings that were required by a previous building permit to install a vented kitchen range hood or other kitchen exhaust fan shall install a replacement fan that meets or exceeds the airflow required by the previous building permit, or 100 cfm, whichever is greater.
    3. Dwellings that were not required to have a kitchen local ventilation exhaust system according to the conditions in either Subsection 1 or 2 above shall not be required to comply with the requirements of Section 150.0(o)1G.

    c. Replacement ventilation fans. New or replacement local mechanical exhaust fans shall be rated for airflow and sound in accordance with the requirements of ASHRAE 62.2 Section 7.1 and Title 24, Part 6 Section 150.0(o)1Gvi. Additionally, when compliance with a specified exhaust airflow rate is required, the replacement fan shall be rated at no less than the airflow rate required for compliance.

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    SINGLE-FAMILY RESIDENTIAL BUILDINGS—ADDITIONS AND ALTERATIONS TO EXISTING RESIDENTIAL BUILDINGS

    N. Exterior doors. Alterations that add exterior door area shall meet the U -factor requirement of Section 150.1(c)5. 2. Performance approach. The energy budget for alterations is expressed in terms of long-term system cost (LSC), and the altered component(s) and any newly installed equipment serving the alteration shall meet the applicable requirements of Subsections A, B, and C below.

  • CRC § 150.0 Medium relevance — show source text
    1. Dwellings that were required by a previous building permit to install a vented kitchen range hood or other kitchen exhaust fan shall install a replacement fan that meets or exceeds the airflow required by the previous building permit, or 100 cfm, whichever is greater.
    2. Dwellings that were not required to have a kitchen local ventilation exhaust system according to the conditions in either Subsection 1 or 2 above shall not be required to comply with the requirements of Section 150.0(o)1G.

    c. Replacement ventilation fans. New or replacement local mechanical exhaust fans shall be rated for airflow and sound in accordance with the requirements of ASHRAE 62.2 Section 7.1 and Title 24, Part 6 Section 150.0(o)1Gvi. Additionally, when compliance with a specified exhaust airflow rate is required, the replacement fan shall be rated at no less than the airflow rate required for compliance.

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    SINGLE-FAMILY RESIDENTIAL BUILDINGS—ADDITIONS AND ALTERATIONS TO EXISTING RESIDENTIAL BUILDINGS

    N. Exterior doors. Alterations that add exterior door area shall meet the U -factor requirement of Section 150.1(c)5. 2. Performance approach. The energy budget for alterations is expressed in terms of long-term system cost (LSC), and the altered component(s) and any newly installed equipment serving the alteration shall meet the applicable requirements of Subsections A, B, and C below. A. The altered components shall meet the applicable requirements of Sections 110.0 through 110.9, Sections 150.0(a) through (l), Sections 150.0(m)1 through 150.0 (m)10, and Sections 150.0(p) through (q). Entirely new or complete replacement mechanical ventilation systems, as these terms are used in Section 150.2(b)1L, shall comply with the requirements in Section 150.2(b)1L. Altered mechanical ventilation systems shall comply with the requirements of Section 150.2(b)1M. Entirely new or complete replacement space-conditioning systems, and entirely new or complete replacement duct systems, as these terms are used in Sections 150.2(b)1C and 150.2(b)1Diia, shall comply with the requirements of Sections 150.0(m)12 and 150.0(m)13. B. The standard design for an altered component shall be the higher efficiency of existing conditions or the requirements stated in Table 150.2-G. For components not being altered, the standard design shall be based on the existing conditions. When the third party verification option is specified as a requirement, all components proposed for alteration for which the additional credit is taken must be verified by a certified ECC-Rater.

  • CRC § 203.1.2 Medium relevance — show source text

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    APPENDIX A4 — RESIDENTIAL VOLUNTARY MEASURES

    A4.203.1.2 Prerequisite options. In addition, a minimum of TWO of the efficiency measures specified in Sections A4.203.1.2.1 through A4.203.1.2.7 must be met.

    A4.203.1.2.1 Roof deck insulation, or ducts in conditioned space. Meet one of the three options for the location of ducts and air handlers as well as insulation R -values and installation of a radiant barrier as specified in Title 24, Part 6, Section 150.1(c)9A or B:

    1. Below roof deck insulation with a minimum R -value of 19; or,

    2. Continuous above deck insulation with a minimum R-8 and with an air space present between the roofing and the roof deck; or,

    3. All ducts and air handlers in conditioned space as specified in the Title 24, Part 6, Reference Appendix RA3.1.

    A4.203.1.2.2 High performance walls. Meet the climate zone dependent U -factor or insulation R -value for either 2x6 or 2x4 framing as specified in Title 24, Part 6, Section 150.1(c)1B: maximum U -factor of 0.048.

    A4.203.1.2.3 Compact hot water distribution system. Meet the requirements for installation of Compact Hot Water Distribution Systems specified in the Title 24, Part 6, Reference Appendix RA3.6.5.

    A4.203.1.2.4 Drain water heat recovery. Meet the requirements for installation of Drain Water Heat Recovery specified in Title 24, Part 6, Reference Appendix RA4.4.21.

    A4.203.1.2.5 High performance vertical fenestration. Meet the climate zone dependent U -factor and Solar Heat Gain Coefficient (SHGC) as rated in accordance with Title 24, Part 6, Section 110.6, and shall have a maximum U -factor of 0.21 in Climate Zones 1 − 16, maximum SHGC of 0.23 in Climate Zones 2, 4, and 6 − 14, and maximum SHGC of 0.20 in Climate Zone 15.

    Exception to A4.203.1.2.5: Fenestration in Climate Zones 1, 3, 5, and 16 is not required to comply with the maximum SHGC requirements.

    A4.203.1.2.6 Heat pump water heater demand management. For buildings with heat pump water heating, meet the requirements for installation of controls specified by Title 24, Part 6, Reference Appendix JA13.3.3.

    A4.203.1.2.7 Battery storage system controls. For buildings with battery storage systems, meet the requirements for installation of controls specified by Title 24, Part 6, Reference Appendix JA12 for either the Time-of-Use Control or Advanced Demand Flexibility Control option.

  • CRC § 1.2. Medium relevance — show source text

    1.2. If the addition constitutes substantial improvement, the existing building and the addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 1.3. If the addition does not constitute substantial improvement, the addition is not required to comply with the flood design requirements for new construction, provided that both of the following apply: 1.3.1. The addition shall not create or extend any nonconformity of the existing building with the flood-resistant construction requirements. 1.3.2. The lowest floor of the addition shall be at or above the lower of the lowest floor of the existing building or the lowest floor elevation required in Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 2. For horizontal additions that are not structurally interconnected to the existing building: 2.1. The addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Resi- dential Code, as applicable. 2.2. If the addition and all other proposed work, when combined, constitute substantial improvement, the existing building and the addition shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 3. For vertical additions and all other proposed work that, when combined, constitute substantial improvement, the existing building shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable. 4. For a new foundation, replacement foundation or a foundation raised or extended upward, the foundation shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable.

    SECTION 1104—ENERGY CONSERVATION

    1104.1 Minimum requirements. Additions to existing buildings shall comply with applicable provisions of the California Energy Code (Part 6, Title 24, C.C.R).

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    12 HISTORIC BUILDINGS

    Chapter 12 is not adopted by the State of California.

    Historic buildings and structures shall comply with Part 8, Title 24, California Code of Regulations.

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    CALIFORNIA EXISTING BUILDING CODE – MATRIX ADOPTION TABLE

    CHAPTER 13 – PERFORMANCE COMPLIANCE METHODS

    Not adopted by the State of California (May be available for adoption by local ordinance. See Section 1.1.11.) (See Section 104.11 for consideration of alternative means of compliance.)

  • CRC § 1.88 Medium relevance — show source text

    85|1.88| |1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|1. NR = Not Required.|

    Note: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code . Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.8 and 25943, Public Resources Code .

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    6 NONRESIDENTIAL AND HOTEL/MOTEL OCCUPANCIES—

    ADDITIONS, ALTERATIONS AND REPAIRS

    SECTION 141.0—ADDITIONS, ALTERATIONS AND REPAIRS TO EXISTING NONRESIDENTIAL AND HOTEL/ MOTEL BUILDINGS, TO EXISTING OUTDOOR LIGHTING, AND TO INTERNALLY AND EXTERNALLY ILLUMINATED SIGNS

    Additions, alterations, and repairs to existing nonresidential and hotel/motel buildings, existing outdoor lighting for these occupancies, and internally and externally illuminated signs, shall meet the requirements specified in Sections 100.0 through 110.12, and 120.0 through 130.5 that are applicable to the building project, and either the performance compliance approach (energy budgets) in Section 141.0(a)2 (for additions) or 141.0(b) 3 (for alterations), or the prescriptive compliance approach in Section 141.0(a)1 (for additions) or 141.0(b)2 (for alterations), for the Climate Zone in which the building is located. Climate zones are shown in Figure 100.1-A.

    Covered process requirements for additions, alterations and repairs to existing nonresidential and hotel/motel buildings are specified in Section 141.1.

    Exception to Section 141.0: Alterations to healthcare facilities are not required to comply with this Section.

    NOTES:

    1. For alterations that change the occupancy classification of the building, the requirements specified in Section 141.0(b) apply to the occupancy after the alterations.
    2. Relocation or moving of a relocatable public school building is not, by itself, considered an alteration for the purposes of Title 24, Part 6.

    (a) Additions. Additions shall meet either Item 1 or 2 below.

    1. **Prescriptive approach.
  • CRC § 180.2 Medium relevance — show source text

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    MULTIFAMILY BUILDINGS—ADDITIONS, ALTERATIONS AND REPAIRS TO EXISTING MULTIFAMILY BUILDINGS

    EXCEPTION 2 to Section 180.2(c): Where the space in the attic or rafter area is not large enough to accommodate the required R- value, the entire space shall be filled with insulation, provided such installation does not violate Section 1203.2 of Title 24, Part 2.

    NOTE: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code . Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.5, 25402.8 and 25943, Public Resources Code .

    SECTION 180.3—REPAIRS

    Repairs shall not increase the preexisting energy consumption of the repaired component, system or equipment.

    NOTE: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code . Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.5, 25402.8 and 25943, Public Resources Code .

    SECTION 180.4 —WHOLE BUILDING

    Any addition or alteration may comply with the requirements of Title 24, Part 6 by meeting the requirements for the entire building.

    NOTE: Authority: Sections 25213, 25218, 25218.5, 25402 and 25402.1, Public Resources Code . Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.5, 25402.8 and 25943, Public Resources Code .

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    CALIFORNIA MECHANICAL CODE, CALIFORNIA CODE OF REGULATIONS, TITLE 24, PART 4, CHAPTER 6, DUCT SYSTEMS

    TABLE P4-A ADOPTION TABLE

    CODE SECTION Col2 AGENCY
    Adopt entire Chapter as amended
    (amended sections listed below)1    		 CEC
    601.0 X
    602.0 X
    603.0 X
    604.0 X
    605.0 X
    1. Adopted by reference for Occupancies A, B, E, F, H, I, L, M, R, S and U; see Sections 110.8(d)3, 120.4 and 150.0(m).

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    1-A STANDARDS AND DOCUMENTS

    REFERENCED IN THE ENERGY CODE

  • CRC § 150.2 Medium relevance — show source text

    For alterations that change the occupancy classification of the building, the requirements specified in Section 150.2 apply to the occupancy after the alterations. C. Multifamily buildings. Section 180.0 applies to new construction in existing multifamily buildings. New construction in existing buildings includes additions, alterations and repairs. Section 180.0 specifies requirements that uniquely apply to additions, alterations or repairs to existing buildings, and specifies which requirements in other sections also apply. For alterations that change the occupancy classification of the building, the requirements specified in Section 180.0 apply to the occupancy after the alterations. 4. Installation of insulation in existing buildings. Section 110.8(d) applies to buildings in which insulation is being installed in existing attics, or on existing water heaters or existing space conditioning ducts. 5. Outdoor lighting. Sections 110.9, 130.0, 130.2, 130.4, 140.7, and 150.0 apply to newly constructed outdoor lighting systems, and Section 141.0 applies to outdoor lighting that is either added or altered. 6. Signs. Sections 130.0, 130.3 and 140.8 apply to newly constructed signs located either indoors or outdoors, and Section 141.0 applies to sign alterations located either indoors or outdoors.

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    ALL OCCUPANCIES—GENERAL PROVISIONS

    (f) Mixed occupancy. When a building is designed and constructed for more than one type of occupancy (residential and nonresidential), the space for each occupancy shall meet the provisions of Part 6 applicable to that occupancy.

    Exception 1 to Section 100.0(f): If one occupancy constitutes at least 80 percent of the conditioned floor area of the building, the entire building envelope, HVAC and water heating may be designed to comply with the provisions of Part 6 applicable to that occupancy, provided that the applicable lighting requirements in Sections 140.6 through 140.8, 150.0(k), or 160.5 and 170.2(e) are met for each occupancy and space, and mandatory measures in Sections 110.0 through 130.5, 150.0, and 160.0 through 160.9 are met for each occupancy and space.

    Exception 2 to Section 100.0(f): If one occupancy constitutes at least 90 percent of the combined conditioned plus unconditioned floor area of the building, the entire building indoor lighting may be designed to comply with only the lighting provisions of Part 6 applicable to that occupancy.

    (g) Administrative requirements. Administrative requirements relating to permit requirements, enforcement by the Commission, locally adopted energy standards, interpretations, claims of exemption, approved calculation methods, rights of appeal, and certification and labeling requirements of fenestration products and roofing products are specified in California Code of Regulations, Title 24, Part 1, Sections 10-101 to 10-114.

    (h) Certification requirements for manufactured equipment, products and devices. Part 6 limits the installation of manufactured equipment, products and devices to those that have been certified as specified by Sections 110.0 and 110.1. Requirements for manufactured equipment, products, and devices, when not specified in Title 24 Part 6, are specified in California Code of Regulations, Title 20, Sections 1601–1609.

  • CRC § 25218.5 Medium relevance — show source text

    Note: Authority: Sections 25213, 25218, 25218.5, 25402, 25402.1, and 25605, Public Resources Code. Reference: Sections 25007, 25008, 25218.5, 25310, 25402, 25402.1, 25402.4, 25402.5, 25402.8, 25605, and 25943, Public Resources Code.

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    9 SINGLE-FAMILY RESIDENTIAL BUILDINGS—ADDITIONS AND

    ALTERATIONS TO EXISTING RESIDENTIAL BUILDINGS

    SECTION 150.2—ENERGY EFFICIENCY STANDARDS FOR ADDITIONS AND

    ALTERATIONS TO EXISTING SINGLE-FAMILY RESIDENTIAL BUILDINGS

    (a) Additions. Additions to existing single-family residential buildings shall meet the requirements of Sections 110.0 through 110.9; Sections 150.0(a) through (n), (p) and (q); and either Section 150.2(a)1 or 2.

    Exception 1 to Section 150.2(a): Additions of 300 square feet or less are not required to comply with the roofing requirements of Section 150.1(c)11.

    Exception 2 to Section 150.2(a): Existing inaccessible piping shall not require insulation as defined under Section 150.0(j)1.

    Exception 3 to Section 150.2(a): Space-conditioning system. When heating or cooling will be extended to an addition from the existing system(s), the existing heating and cooling equipment need not comply with Part 6. The heating system capacity must be adequate to meet the minimum requirements of CRC 303.10.

    Exception 4 to Section 150.2(a): Space-conditioning system ducts. When any length of duct is extended from an existing duct system to serve the addition, the existing duct system and the extended duct shall meet the applicable requirements specified in Section 150.2(b)1Di and 150.2(b)1Dii.

    Exception 5 to Section 150.2(a): Additions 1,000 square feet or less are not required to comply with the ventilation cooling requirements of Section 150.1(c)12.

    Exception 6 to Section 150.2(a): Photovoltaic systems, as specified in Section 150.1(c)14, are not required for additions.

    1. Prescriptive approach. Additions to existing buildings shall meet the following additional requirements: A. Additions that are greater than 700 square feet shall meet the requirements of Section 150.1(c), with the following modifications:

    i. Extensions of existing wood-framed walls may retain the dimensions of the existing walls and shall install cavity insulation of R-15 in a 2 × 4 framing and R-21 in a 2 × 6 framing. ii. The maximum allowed fenestration area shall be the greater of 175 square feet or 20 percent of the addition floor area, and the maximum allowed west-facing fenestration area shall be the greater of 70 square feet or the requirements of Section 150.1(c).

  • CRC § 204.1 Medium relevance — show source text

    ** Buildings complying with the second level of advanced energy efficiency shall have an Energy Budget that is no greater than indicated below, depending on building type and the type of energy systems included in the building project. If the newly constructed building or addition does not include indoor lighting or mechanical systems, then no additional performance requirements above Title 24, Part 6 are required.

    1. For nonresidential building projects that include indoor lighting or mechanical systems, but not both: No greater than 90 percent of the Title 24, Part 6, Energy Budget for the Standard Design Building as calculated by compliance software certified by the Energy Commission.
    2. For nonresidential building projects that include indoor lighting and mechanical systems: No greater than 85 percent of the Title 24, Part 6, Energy Budget for the Standard Design Building as calculated by compliance software certified by the Energy Commission.
    3. For high-rise residential and hotel/motel building projects: No greater than 95 percent of the Title 24, Part 6, Energy Budget for the Standard Design Building as calculated by compliance software certified by the Energy Commission.

    Note: For Energy Budget calculations, high-rise residential and hotel/motel buildings are considered nonresidential buildings.

    SECTION A5.204—MANDATORY REQUIREMENTS FOR ALTERATIONS TO EXISTING BUILDINGS

    A5.204.1 Energy efficiency . Alterations to existing nonresidential buildings shall comply with Section A5.204.1.1.

    A5.204.1.1 Altered pool and/or spa heating for existing nonresidential buildings . Alteration of existing nonresidential pool and/or spa heating system shall meet the following.

    Heating source sizing. Heating systems or equipment for pools or spas shall meet one of the sizing requirements of Items 1 through 5 below:

    1. Solar pool heating system with a solar collector surface area that is equivalent to 65 percent or greater of the surface areas of the pool or spa or a combination of both respectively; or
    2. A heat pump pool heater as the primary heating system that meets the sizing requirements of Reference Joint Appendix JA16.3. The control for the heat pump pool heater shall meet the requirements specified in Section 110.4(d). The supplementary heater can be of any energy source; or
    3. A heating system that derives at least 60 percent of the annual heating energy from on-site renewable energy or on-site recovered energy; or
    4. A combination of a solar pool heating system and heat pump pool heater without any additional supplementary heater;

    or

    1. A pool heating system determined by the Energy Commission Executive Director to use no more energy than the systems specified in Item 1, 2, 3, or 4 above.

    Exception 1 to A5.204.1.1: Portable electric spas compliant with 20 CCR, Section 1605.3(g)(7) of the Appliance Efficiency Regulations.

    Exception 2 to A5.204.1.1: A pool or spa that is heated solely by a solar pool heating system without any supplementary heater.

    Exception 3 to A5.204.1.1: An existing building with inadequate Solar Access Roof Area (SARA) as specified in Section 140.10(a) for a solar pool heating system to be installed.

    Exception 4 to A5.204.1.1: Heating systems which are used exclusively for permanent spa applications in existing buildings with gas availability.

    SECTION A5.211—RESERVED

    SECTION A5.212—ELEVATORS, ESCALATORS AND OTHER EQUIPMENT

  • CRC § 1104.1 Medium relevance — show source text
    1. For a new foundation, replacement foundation or a foundation raised or extended upward, the foundation shall comply with Section 1612 of the California Building Code, or Section R306 of the California Residential Code, as applicable.

    SECTION 1104—ENERGY CONSERVATION

    1104.1 Minimum requirements. Additions to existing buildings shall comply with applicable provisions of the California Energy Code (Part 6, Title 24, C.C.R).

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    12 HISTORIC BUILDINGS

    Chapter 12 is not adopted by the State of California.

    Historic buildings and structures shall comply with Part 8, Title 24, California Code of Regulations.

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    CALIFORNIA EXISTING BUILDING CODE – MATRIX ADOPTION TABLE

    CHAPTER 13 – PERFORMANCE COMPLIANCE METHODS

    Not adopted by the State of California (May be available for adoption by local ordinance. See Section 1.1.11.) (See Section 104.11 for consideration of alternative means of compliance.)

    Adopting Agency BSC BSC-
    CG    		 SFM HCD Col6 Col7 DSA Col9 Col10 OSHPD Col12 Col13 Col14 Col15 Col16 Col17 BSCC DPH AGR DWR CEC CA SL SLC
    Adopting Agency BSC BSC-
    CG    		 SFM 1 2 1/AC AC SS SS/CC 1 1R 2 3 4 5 6 6 6 6 6 6 6 6 6
    Adopt Entire Chapter
    Adopt Entire Chapter as
    amended (amended
    sections listed below)
    Adopt only those sections
    that are listed below
    Chapter / Section

    The state agency does not adopt sections identified with the following symbol: The Office of the State Fire Marshal’s adoption of this chapter or individual sections is applicable to structures regulated by other state agencies pursuant to Section 1.11.

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Frequently asked questions

Do additions always trigger Part 6 compliance?

Yes. Additions are required to comply with Title 24, Part 6; see § 1104.1. Check the specific Part 6 sections (150.1/150.2) for prescriptive requirements and small‑addition exceptions.

Are Appendix A4 requirements mandatory statewide?

No. Appendix A4 is voluntary statewide; it becomes mandatory only if a local jurisdiction adopts it per the process described in A4.201.1. Always verify local adoption.

If I replace only a furnace, does A4.204.1 apply?

A4.204.1 focuses on alterations to existing residential buildings and specifically calls out altered space‑conditioning systems (A4.204.1.1) for cooling equipment replacement. Whether a furnace replacement triggers Part 6 or Appendix A4 rules depends on the specific equipment and local adoption; consult the referenced Energy Code sections (e.g., § 150.2 and § 150.0) and A4 text.

What tests are required when A4.204.1.1.b is used?

Field verification and diagnostic testing per the Reference Residential Appendix are required: duct leakage measured as ≤ 5% of system airflow (RA3.1.4.3.1) and airflow/fan efficacy per RA3.3 procedures.

Where in the Energy Code are small‑addition exceptions listed?

See Section 150.2 for prescriptive rules for additions and its listed exceptions (e.g., roofing exception for additions ≤ 300 sq ft, other size limits).

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Existing Building Code — Additions and energy conservation (1104.1)

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