Title 24 · California Energy Code
How to determine annual solar access (the 70% rule) and apply it to SARA
The code says: measure annual insolation with and without shade; if the shaded/unshaded ratio is below 70% exclude that roof area from SARA. For PV sizing use the smaller of the equation result or SARA×18 W/ft² (steep) or ×14 W/ft² (low), and follow the multifamily distinctions where steep roofs only consider external permanent obstructions.
Last reviewed: July 6, 2026
What the code requires — plain English (controlling §)
- Annual solar access is the ratio of annual solar insolation with shading to the annual insolation without shading, and any roof area that has less than 70% annual solar access must be excluded from the building’s solar access roof area (SARA). See § 140.10(a) and § 170.2(f) for the rule and SARA definition.
- For PV sizing the code uses the smaller of (a) the equation-based system size or (b) the SARA-based size (SARA × 18 W/ft² for steep roofs or 14 W/ft² for low-sloped roofs). See § 140.10(a) and § 170.2(f).
Exclude any roof area with less than 70% annual solar access (annual shaded insolation ÷ annual unshaded insolation < 0.70) when computing SARA for PV sizing. This is the single, controlling test.
Requirements in detail
Key defined terms (first mentions)
- Annual solar access — the ratio of total annual solar insolation accounting for shading obstructions to the total annual insolation if the same area were unshaded. 70% is the threshold. § 140.10(a), § 170.2(f).
- SARA (Solar Access Roof Area) — roof area that is structurally capable of supporting PV plus covered parking/carport roof areas and other newly constructed site structures that can support PV. § 140.10(a), § 170.2(f).
How to determine annual solar access (the calculation)
- Compute annual insolation for the candidate roof area:
- Numerator = total annual solar insolation including shading from the obstructions being considered.
- Denominator = total annual solar insolation for the same area if unshaded.
- Annual solar access = Numerator ÷ Denominator.
- If the fraction < 0.70, that roof area is excluded from SARA. § 140.10(a), § 170.2(f).
Which obstructions count (decision split)
- For all roofs under § 140.10(a): the code states all obstructions, including those external to the building and those that are part of building design/elevation features, may be considered in the annual solar access calculation. § 140.10(a).
- For multifamily up to three stories under § 170.2(f) the code distinguishes:
- Steep‑sloped roofs — only shading from existing permanent natural or manmade obstructions that are external to the dwelling (trees, hills, adjacent structures, etc.) shall be considered. § 170.2(f).
- Low‑sloped roofs — all obstructions may be considered, including those that are part of building design/elevation features. § 170.2(f).
How SARA is used for PV sizing
- PV sizing takes the smaller of:
- Equation-based system capacity (Equation 140.10‑A for nonresidential or Equation 170.2‑C/170.2‑D for multifamily), or
- SARA × 18 W/ft² for steep‑sloped roofs, or SARA × 14 W/ft² for low‑sloped roofs. § 140.10(a), § 170.2(f).
Decision‑relevant dimensions and values
| Decision item | Value / rule | When it matters | Code reference |
|---|---|---|---|
| Annual solar access threshold | 70% | Include or exclude roof area from SARA | § 140.10(a) |
| How to compute annual access | Shaded annual insolation ÷ unshaded annual insolation | Always (annual basis) | § 140.10(a) |
| Obstructions considered — all roofs | All obstructions (external and building features) may be considered | General (non‑multifamily or where §140.10 applies) | § 140.10(a) |
| Obstructions considered — multifamily steep roofs | Only existing permanent external obstructions (trees, hills, adjacent structures) | Multifamily ≤ 3 stories, steep roofs | § 170.2(f) |
| Obstructions considered — multifamily low roofs | All obstructions, including those part of building design | Multifamily ≤ 3 stories, low slope | § 170.2(f) |
| SARA → PV conversion (steep) | Multiply SARA by 18 W/ft² | To compute SARA‑based size | § 140.10(a), § 170.2(f) |
| SARA → PV conversion (low) | Multiply SARA by 14 W/ft² | To compute SARA‑based size | § 140.10(a), § 170.2(f) |
| Small‑roof exceptions | No PV required if SARA < 80 contiguous ft² | Exemption from required PV | § 140.10(a), § 170.2(f) |
| Small capacity exception | No PV required if required PV < 4 kW dc (nonresidential/multifamily) | Exemption from required PV | § 140.10(a), § 170.2(f) |
| Minimum SARA relative to building size | No PV required where total available SARA < 3% of conditioned floor area (CFA) | Exemption | § 140.10(a) |
Exceptions & special cases
- Occupied roof areas are excluded from SARA as specified by the Building Code (CBC § 503.1.4) — the energy code refers to that exclusion. § 140.10(a), § 170.2(f) mention this exclusion.
- For multifamily steep roofs there is also an azimuth limitation: steep roof areas with a northerly azimuth between 300° and 90° (i.e., north-facing) may not be considered for SARA per the steep‑roof exception in § 170.2(f).
- There are standard exceptions to the PV requirement tied to SARA size, minimum PV capacity, and snow‑load/structural feasibility — see the exception list in § 140.10(a) and § 170.2(f). Examples: 3% of CFA, <4 kW, <80 contiguous ft², or enforcement‑authority approval where PV cannot meet ASCE snow‑load requirements.
- Note: some other code sections (for solar zone design) treat rooftop obstructions differently (e.g., §§ 110.10(b) solar zone rules). Those are related but not a substitute for the annual solar access calculation used to form SARA.
Common mistakes
- Treating monthly or seasonal shadowing tests as the code’s required metric — the code requires an annual insolation ratio. Always use an annual calculation.
- Applying the same obstruction rule to all building types — multifamily § 170.2(f) differentiates steep vs low slope obstructions; do not apply the multifamily steep‑roof restriction to other occupancies unless § 140.10(a) or the applicable section directs it.
- Including roof‑mounted obstructions (vents, equipment) incorrectly: some other provisions (solar zone rules, § 110.10) prohibit certain roof obstructions inside a solar zone; do not conflate those rooftop‑zone rules with the annual solar access computation unless the specific solar‑zone section applies.
- Forgetting occupied roofs exclusion (CBC § 503.1.4) when tallying SARA.
Worked example — concrete scenario (multifamily, low‑sloped roof)
Scenario facts (example):
- Building: 3‑story multifamily, low‑sloped roof.
- Roof candidate areas: Area A = 1,200 ft² (measured insolation shows 82% annual solar access); Area B = 600 ft² (measured 68% annual solar access); Area C = 400 ft² (measured 75% annual solar access).
- Conditioned floor area (CFA) and equation factors: CFA = 20,000 ft². (We will compute only SARA‑based PV size because the table values needed for Equation 170.2‑C are not fully available in the retrieved text.)
Step 1 — apply the 70% test (annual):
- Area A: 82% ≥ 70% → include → contributes 1,200 ft² to SARA.
- Area B: 68% < 70% → exclude → contributes 0 ft² to SARA.
- Area C: 75% ≥ 70% → include → contributes 400 ft² to SARA.
SARA total = 1,200 + 400 = 1,600 ft².
Step 2 — convert SARA to PV capacity (low‑sloped multiplier = 14 W/ft² for SARA‑based size per § 170.2(f)):
- SARA‑based PV = 1,600 ft² × 14 W/ft² = 22,400 W = 22.4 kW dc. § 170.2(f).
Step 3 — pick the smaller of (a) Equation result and (b) SARA result:
- Equation 170.2‑C would produce an alternate required kW (kW PV = (CFA × A)/1000 + NDU×B); that requires the climate‑zone factor from tables not fully reproduced here, so we cannot compute it from the retrieved text. If Equation 170.2‑C produced, for example, 18 kW, the code would require the smaller value, 18 kW. If Equation produced 25 kW, the code would require the smaller value, 22.4 kW (SARA‑based). See § 170.2(f) and Equation 170.2‑C.
Notes on the example:
- If the building’s total available SARA had been < 3% of CFA (3% of 20,000 ft² = 600 ft²), an exception might apply and no PV would be required. Check § 140.10(a) and § 170.2(g) exceptions.
Related provisions
- § 140.10(a) — Photovoltaic requirements, SARA definition and 70% rule (nonresidential/hotel/motel).
- § 170.2(f) — Photovoltaic requirements and annual solar access rules for multifamily (≤ 3 habitable stories) with steep vs low‑slope distinctions.
- Equation 170.2‑C / 170.2‑D — Annual PV output equations referenced for multifamily sizing; these are the equation alternative to the SARA multiplier method.
- § 110.10(b) — Solar zone rules and solar‑zone exceptions (useful where solar zone layout is being planned and may interact with SARA).
- CBC § 503.1.4 — Reference for occupied roof exclusion (referenced by §§ 140.10 and 170.2).
If you want, I can:
- produce a step‑by‑step checklist you can use on drawings to measure and document SARA, or
- create a short template calculation sheet (spreadsheet style) that follows the example above and records the required file‑backed citations.
Code references
Grounded in the retrieved California Energy Code — click a citation to read the verbatim passage:
§ 170.2 High relevance — show source text
The PV capacity in kW dc shall not be less than the smaller of the minimum rated PV system capacity determined by Equation 170.2-D, or the total of all available solar access roof areas (SARA) multiplied by 18 for steep-sloped roofs or multiplied by 14 for low-sloped roofs. In mixed occupancy buildings, the minimum rated PV system capacity for the building shall be determined by applying Equation 170.2-D to the conditioned floor area of each of the listed building types and summing the capacities determined for each.
SARA include the area of the building’s roof space capable of structurally supporting a PV system, and the area of all roof space on covered parking areas, carports and all other newly constructed structures on the site that are compatible with supporting a PV system per Title 24, Part 2, Section 1511.10.
SARA does not include:
A. Any area that has less than 70 percent annual solar access. Annual solar access is determined by dividing the total annual solar insolation (accounting for shading obstructions) by the total annual solar insolation if the same areas were unshaded by those obstructions. For all roofs, all obstructions including those that are external to the building,
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and obstructions that are part of the building design and elevation features, may be considered for the annual solar access calculations.
B. Occupied roofs as specified by CBC Section 503.1.4. C. Roof area that is otherwise not available due to compliance with: i. Other state building code requirements, or ii. Local building code requirements if the local building code requirements are confirmed by the Executive Director.
EQUATION 170.2-D—PHOTOVOLTAIC DIRECT CURRENT CAPACITY
kW PVdc = (CFA × A)/1000
where:
kW PVdc = Minimum rated PV system capacity in kW.
CFA = Conditioned floor area in square feet.
A = PV capacity factor in W/square foot as specified in Table 170.2-U for the building type.
Exception 1 to Section 170.2(g): No PV system is required where the total of all available SARA is less than 3 percent of the conditioned floor area.
Exception 2 to Section 170.2(g): No PV system is required where the required PV system capacity is less than 4 kW dc .
Exception 3 to Section 170.2(g): No PV system is required if the SARA contains less than 80 contiguous square feet.
Exception 4 to Section 170.2(g): Buildings with enforcement-authority-approved roof designs, where the enforcement authority determines it is not possible for the PV system, including panels, modules, components, supports and attachments to the roof structure, to meet ASCE 7-16, Chapter 7, Snow Loads.
§ 1511.10. High relevance — show source text
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A. SARA includes the area of the building’s roof space capable of structurally supporting a PV system, and the area of all roof space on covered parking areas, carports and all other newly constructed structures on the site that are compatible with supporting a PV system per Title 24, Part 2, Section 1511.10.
B. SARA does NOT include:
i. Any roof area that has less than 70 percent annual solar access. Annual solar access is determined by dividing the total annual solar insolation, accounting for shading obstructions, by the total annual solar insolation if the same areas were unshaded by obstructions. For steep slope roofs, only shading from existing permanent natural or manmade obstructions that are external to the dwelling, including but not limited to trees, hills, and adjacent structures, shall be considered for annual solar access calculations. For low slope roofs, all obstructions, including those that are external to the dwelling unit, and obstructions that are part of the building design and elevation features shall be considered for the annual solar access calculations. ii. Occupied roof areas as specified by CBC Section 503.1.4. iii. Roof area that is otherwise not available due to compliance with: a. Other state building code requirements, or b. Local building code requirements if local building code requirements are confirmed by the Executive Director .
EQUATION 150.1-C—ANNUAL PHOTOVOLTAIC ELECTRICAL OUTPUT kW PV = (CFA × A)/1000 +(N DU × B)
where:
kW PV = kW dc size of the PV system.
CFA = Conditioned floor area.
N DU = Number of dwelling units. A = CFA adjustment factor from Table 150.1-C. B = Dwelling unit adjustment factor from Table 150.1-C. Exception 1 to Section 150.1(c)14: For steep slope roofs, SARA shall not consider roof areas with a northerly azimuth that lies between 300 degrees and 90 degrees from true north. No PV system is required if the SARA is less than 80 contiguous square feet. Exception 2 to Section 150.1(c)14: No PV system is required when the minimum PV system size specified by Section 150.1(c)14 is less than 1.8 kW dc . Exception 3 to Section 150.1(c)14: Buildings with enforcement-authority-approved roof designs, where the enforcement authority determines it is not possible for the PV system, including panels, modules and components and supports and attachments to the roof structure, to meet the requirements of the American Society of Civil Engineers (ASCE), Standard 7-16, Chapter 7, Snow Loads. Exception 4 to Section 150.1(c)14: For buildings that are approved by the local planning department prior to January 1, 2020 with mandatory conditions for approval: a. Shading from roof designs and configurations for steep-sloped roofs, which are required by the mandatory conditions for approval, shall be considered for the annual solar access calculations; and b. Roof areas that are not allowed by the mandatory conditions for approval to have PVs shall not be considered in determining the SARA.
§ 1511.10. High relevance — show source text
SARA includes the area of the building’s roof space capable of structurally supporting a PV system, and the area of all roof space on covered parking areas, carports and all other newly constructed structures on the site that are compatible with supporting a PV system per Title 24, Part 2, Section 1511.10.
SARA does NOT include:
A. Any area that has less than 70 percent annual solar access. Annual solar access is determined by dividing the total annual solar insolation (accounting for shading obstructions) by the total annual solar insolation if the same areas were unshaded by those obstructions. For all roofs, all obstructions, including those that are external to the building, and obstructions that are part of the building design and elevation features may be considered for the annual solar access calculations.
B. Occupied roofs as specified by CBC Section 503.1.4. C. Roof area that is otherwise not available due to compliance with: i. Other state building code requirements; or ii. Local building code requirements if the local building code requirements are confirmed by the Executive Director.
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COMPLIANCE APPROACHES FOR ACHIEVING ENERGY EFFICIENCY
EQUATION 140.10-A—PHOTOVOLTAIC DIRECT CURRENT CAPACITY
kW PVdc = (CFA × A)/1000
where:
kW PVdc = Minimum rated PV system capacity in kW.
CFA = Conditioned floor area in square feet.
A = PV capacity factor in W/square foot as specified in Table 140.10-A for the building type.
Exception 1 to Section 140.10(a): No PV system is required where the total of all available SARA is less than 3 percent of the conditioned floor area.
Exception 2 to Section 140.10(a): No PV system is required where the required PV system capacity is less than 4 kW dc .
Exception 3 to Section 140.10(a): No PV system is required if the SARA contains less than 80 contiguous square feet.
Exception 4 to Section 140.10(a): Buildings with enforcement-authority-approved roof designs, where the enforcement authority determines it is not possible for the PV system, including panels, modules, components, supports and attachments to the roof structure, to meet ASCE 7-16, Chapter 7, Snow Loads.
Exception 5 to Section 140.10(a): For nonresidential and hotel/motel multitenant buildings, the PV capacity determined by Equation 140.10-A shall be calculated without including tenant spaces meeting all of the following: i. The tenant space is less than or equal to 2,000 square feet of conditioned space; ii. The tenant space is served by an HVAC system that does not serve other tenant spaces in the building; and iii. The tenant space has an individual utility meter to track electricity consumption that does not include the electricity consumption of other tenant spaces in the building.
This exception does not apply where the Commission has approved a community solar program for showing compliance as specified in Title 24, Part 1, Section 10-115, or where a load-serving entity provides a program where PV generation is compensated through virtual energy bill credits for occupants of nonresidential and hotel/motel tenant spaces to receive energy bill benefits from netting of energy generation and consumption.
§ 170.2 High relevance — show source text
b. Roof areas that are not allowed to have PVs by the mandatory conditions of approval shall not be considered in determining the SARA.
Exception 5 to Section 170.2(f): PV system sizes determined using Equation 170.2-C may be reduced by 25 percent if installed in conjunction with a BESS. The BESS shall meet the qualification requirements specified in Joint Appendix JA12 and have a minimum cycling capacity of 7.5 kWh as defined in Joint Appendix JA12.
TABLE 170.2-T—CFA AND DWELLING UNIT ADJUSTMENT FACTORS Col2 Col3 CLIMATE ZONE A—CFA B—DWELLING UNITS 1 0.793 1.27 2 0.621 1.22 3 0.628 1.12 4 0.586 1.21 5 0.585 1.06 6 0.594 1.23 7 0.572 1.15 8 0.586 1.37 9 0.613 1.36 10 0.627 1.41 11 0.836 1.44 12 0.613 1.40 13 0.894 1.51 14 0.741 1.26 15 1.56 1.47 16 0.59 1.22 (g) Photovoltaic requirements—more than three habitable stories. All newly constructed building types specified in Table 170.2-U, or mixed occupancy buildings where at least 80 percent of the floor area of the building serves one or more of these building types, shall have a newly installed photovoltaic (PV) system meeting the minimum qualification requirements of Reference Joint Appendix JA11. The PV capacity in kW dc shall not be less than the smaller of the minimum rated PV system capacity determined by Equation 170.2-D, or the total of all available solar access roof areas (SARA) multiplied by 18 for steep-sloped roofs or multiplied by 14 for low-sloped roofs. In mixed occupancy buildings, the minimum rated PV system capacity for the building shall be determined by applying Equation 170.2-D to the conditioned floor area of each of the listed building types and summing the capacities determined for each.
SARA include the area of the building’s roof space capable of structurally supporting a PV system, and the area of all roof space on covered parking areas, carports and all other newly constructed structures on the site that are compatible with supporting a PV system per Title 24, Part 2, Section 1511.10.
SARA does not include:
A. Any area that has less than 70 percent annual solar access. Annual solar access is determined by dividing the total annual solar insolation (accounting for shading obstructions) by the total annual solar insolation if the same areas were unshaded by those obstructions. For all roofs, all obstructions including those that are external to the building,
2025 CALIFORNIA ENERGY CODE 267
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
MULTIFAMILY BUILDINGS—PERFORMANCE AND PRESCRIPTIVE COMPLIANCE APPROACHES
and obstructions that are part of the building design and elevation features, may be considered for the annual solar access calculations.
§ 170.2 High relevance — show source text
All multifamily buildings up to three habitable stories shall have a newly installed photovoltaic (PV) system or newly installed PV modules meeting the minimum qualification requirements specified in Joint Appendix JA11. The annual electrical output of the PV system shall be no less than the smaller of a PV system size determined using Equation 170.2-C, or the total solar access roof area (SARA) multiplied by 18 for steep-sloped roofs or SARA multiplied by 14 for low-sloped roofs. A. SARA includes the area of the building’s roof space capable of structurally supporting a PV system, and the area of all roof space on covered parking areas, carports, and all other newly constructed structures on the site that are compatible with supporting a PV system per Title 24, Part 2, Section 1511.10.
B. SARA does NOT include:
i. Any roof area that has less than 70 percent annual solar access. Annual solar access is determined by dividing the total annual solar insolation, accounting for shading obstructions, by the total annual solar insolation if the same areas were unshaded by obstructions. For steep-sloped roofs, only shading from existing permanent natural or manmade obstructions that are external to the dwelling, including but not limited to trees, hills and adjacent structures, shall be considered for annual solar access calculations. For low slope roofs, all obstructions including those that are external to the dwelling unit, and obstructions that are part of the building design and elevation features, shall be considered for the annual solar access calculations.
ii. Occupied roof areas as specified by CBC Section 503.1.4. iii. Roof area that is otherwise not available due to compliance with: a. Other state building code requirements, or b. Local building code requirements if local building code requirements are confirmed by the Executive Director.
EQUATION 170.2-C—ANNUAL PHOTOVOLTAIC ELECTRICAL OUTPUT
kW PV = (CFA × A)/1000 + N DU × B)
where:
kW PV = kW dc size of the PV system.
CFA = Conditioned floor area.
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N DU = Number of dwelling units.
A = CFA adjustment factor from Table 170.2-T.
B = Dwelling unit adjustment factor from Table 170.2-T.
Exception 1 to Section 170.2(f): For steep slope roofs, SARA shall not consider roof areas with a northerly azimuth that lies between 300 degrees and 90 degrees from true north. No PV system is required if the SARA is less than 80 contiguous square feet.
Exception 2 to Section 170.2(f): No PV system is required when the minimum PV system size specified by Section 170.2(f) is less than 4 kW dc .
Exception 3 to Section 170.2(f): Buildings with enforcement-authority-approved roof designs, where the enforcement authority determines it is not possible for the PV system, including panels, modules and components and supports and attachments to the roof structure, to meet the requirements of American Society of Civil Engineers (ASCE) Standard 7-16, Chapter 7, Snow Loads.
§ 170.2 High relevance — show source text
ii. Reserved.
iii. Neon or cold cathode lamps with transformer or power supply efficiency greater than or equal to the following: a. A minimum efficiency of 75 percent when the transformer or power supply rated output current is less than 50 mA; or
b. A minimum efficiency of 68 percent when the transformer or power supply rated output current is 50 mA or greater. The ratio of the output wattage to the input wattage is at 100 percent tubing load.
iv. Reserved.
v. Light emitting diodes (LEDs) with a power supply having an efficiency of 80 percent or greater; or Exception to Section 170.2(e)7Bv: Single voltage external power supplies that are designed to convert 120 volt AC input into lower voltage DC or AC output, and have a nameplate output power less than or equal to 250 watts, shall comply with the applicable requirements of the Appliance Efficiency Regulations (Title 20). Exception 1 to Section 170.2(e)7: Unfiltered incandescent lamps that are not part of an electronic message center (EMC), an internally illuminated sign or an externally illuminated sign. Exception 2 to Section 170.2(e)7: Exit signs. Exit signs shall meet the requirements of the Appliance Efficiency Regulations. Exception 3 to Section 170.2(e)7: Traffic signs that meet the requirements of the Appliance Efficiency Regulations, Sections 1601(m), 1602, 1602.1, 1603, 1604(m), 1605, 1605.1(m), 1605.2(m), 1605.3(m), 1606, 1607, 1608, and 1609.
(f) Photovoltaic requirements—three habitable stories or fewer . All multifamily buildings up to three habitable stories shall have a newly installed photovoltaic (PV) system or newly installed PV modules meeting the minimum qualification requirements specified in Joint Appendix JA11. The annual electrical output of the PV system shall be no less than the smaller of a PV system size determined using Equation 170.2-C, or the total solar access roof area (SARA) multiplied by 18 for steep-sloped roofs or SARA multiplied by 14 for low-sloped roofs. A. SARA includes the area of the building’s roof space capable of structurally supporting a PV system, and the area of all roof space on covered parking areas, carports, and all other newly constructed structures on the site that are compatible with supporting a PV system per Title 24, Part 2, Section 1511.10.
B. SARA does NOT include:
i. Any roof area that has less than 70 percent annual solar access. Annual solar access is determined by dividing the total annual solar insolation, accounting for shading obstructions, by the total annual solar insolation if the same areas were unshaded by obstructions. For steep-sloped roofs, only shading from existing permanent natural or manmade obstructions that are external to the dwelling, including but not limited to trees, hills and adjacent structures, shall be considered for annual solar access calculations. For low slope roofs, all obstructions including those that are external to the dwelling unit, and obstructions that are part of the building design and elevation features, shall be considered for the annual solar access calculations.
ii. Occupied roof areas as specified by CBC Section 503.1.4. iii. Roof area that is otherwise not available due to compliance with: a. Other state building code requirements, or b. Local building code requirements if local building code requirements are confirmed by the Executive Director.
§ 150.1 High relevance — show source text
Exception 1 to Section 150.1(c)11: Building integrated photovoltaic panels and building integrated solar thermal panels are not required to comply with the minimum requirements for aged solar reflectance and thermal emittance or SRI. Exception 2 to Section 150.1(c)11: Roof constructions with a weight of at least 25 lb/ft [2] are not required to comply with the minimum requirements for aged solar reflectance and thermal emittance or SRI. 12. Ventilation cooling. Single-family homes shall comply with the whole-house fan (WHF) requirements shown in Table 150.1A. When a WHF is required, comply with Subsections A, B and C below. A. Have installed one or more WHFs whose total airflow cfm is equal to or greater than 1.5 cfm/ft [2] of conditioned floor area. Airflow cfm for WHFs shall be determined based on the airflow listed in the Home Ventilating Institute Certified Products Directory. B. Have at least 1 square foot of attic vent free area for each 750 cfm of rated whole-house fan airflow cfm, or if the manufacturer has specified a greater free vent area, the manufacturer’s free vent area specifications. Exception to Section 150.1(c)12B: WHFs that are directly vented to the outside. C. Provide homeowners who have WHFs with a one page “How to operate your whole-house fan” informational sheet. Exception to Section 150.1(c)12: New dwelling units with a conditioned floor area of 500 square feet or less shall not be required to comply with the WHF requirements. 13. HVAC system bypass ducts. Bypass ducts that deliver conditioned supply air directly to the space-conditioning system return duct airflow shall not be used.
- Photovoltaic requirements. All single-family residential buildings shall have a newly installed photovoltaic (PV) system or newly installed PV modules meeting the minimum qualification requirements specified in Joint Appendix JA11. The annual electrical output of the PV system shall be no less than the smaller of a PV system size determined using Equation 150.1-C, or the total solar access roof area (SARA) multiplied by 18 for steep-sloped roofs or multiplied by 14 for low-sloped roofs.
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A. SARA includes the area of the building’s roof space capable of structurally supporting a PV system, and the area of all roof space on covered parking areas, carports and all other newly constructed structures on the site that are compatible with supporting a PV system per Title 24, Part 2, Section 1511.10.
B. SARA does NOT include:
i. Any roof area that has less than 70 percent annual solar access. Annual solar access is determined by dividing the total annual solar insolation, accounting for shading obstructions, by the total annual solar insolation if the same areas were unshaded by obstructions. For steep slope roofs, only shading from existing permanent natural or manmade obstructions that are external to the dwelling, including but not limited to trees, hills, and adjacent structures, shall be considered for annual solar access calculations. For low slope roofs, all obstructions, including those that are external to the dwelling unit, and obstructions that are part of the building design and elevation features shall be considered for the annual solar access calculations.
§ 110.10 High relevance — show source text
Exception 3 to Section 110.10(b)1B: Buildings with a designated solar zone area that is no less than 50 percent of the potential solar zone area. The potential solar zone area is the total area of any low-sloped roofs where the annual solar access is 70 percent or greater and any steep-sloped roofs oriented between 90 degrees and 300 degrees of true north where the annual solar access is 70 percent or greater. Solar access is the ratio of solar insolation including shade to the solar insolation without shade. Shading from obstructions located on the roof or any other part of the building shall not be included in the determination of annual solar access.
Exception 4 to Section 110.10(b)1B: Low-rise and high-rise multifamily buildings with all thermostats in each dwelling unit are demand response controls that comply with Section 110.12(a), and are capable of receiving and responding to Demand Response Signals prior to granting of an occupancy permit by the enforcing agency. In addition, either A or B below:
A. In each dwelling unit, comply with one of the following measures: i. Install a dishwasher that meets or exceeds the ENERGY STAR Program requirements with either a refrigerator that meets or exceeds the ENERGY STAR Program requirements or a whole house fan driven by an electronically commutated motor; or ii. Install a home automation system that complies with Section 110.12(a) and is capable of, at a minimum, controlling the appliances and lighting of the dwelling and responding to demand response signals; or iii. Install alternative plumbing piping to permit the discharge from the clothes washer and all showers and bathtubs to be used for an irrigation system in compliance with the California Plumbing Code and any applicable local ordinances; or iv. Install a rainwater catchment system designed to comply with the California Plumbing Code and any applicable local ordinances, and that uses rainwater flowing from at least 65 percent of the available roof
area.
B. Meet the Title 24, Part 11, Section A4.106.8.2 requirements for electric vehicle charging spaces.
Exception 5 to Section 110.10(b)1B: Buildings where the roof is designed and approved to be used for vehicular traffic or parking or for a heliport. 2. Azimuth range. All sections of the solar zone located on steep-sloped roofs shall have an azimuth range between 90 degrees and 300 degrees of true north. 3. Shading. A. No obstructions, including but not limited to, vents, chimneys, architectural features and roof mounted equipment, shall be located in the solar zone.
B. Any obstruction, located on the roof or any other part of the building that projects above a solar zone shall be located at least twice the distance, measured in the horizontal plane, of the height difference between the highest point of the obstruction and the horizontal projection of the nearest point of the solar zone, measured in the vertical plane. Exception to Section 110.10(b)3: Any roof obstruction, located on the roof or any other part of the building, that is oriented north of all points on the solar zone. 4. Structural design loads on construction documents. For areas of the roof designated as solar zone, the structural design loads for roof dead load and roof live load shall be clearly indicated on the construction documents.
Note: Section 110.10(b)4 does not require the inclusion of any collateral loads for future solar energy systems.
§ 409.4 High relevance — show source text
Shading from obstructions located on the roof or any other part of the building shall not be included in the determination of annual solar access.
3.
Life cycle assessment compliant with Section A5.409.4 in this code may be substituted for prescriptive measures from Division A5.4.|1.
Exception: Allowance may be permitted in Tier 2 for up to 5-percent specialty purpose flooring.
2.
Solar water-heating system requirement for newly constructed restaurants as per A5.203.1.1.2.
Exceptions:
a. Buildings with a natural gas service water heater with a minimum of 95-percent thermal efficiency.
b. Buildings where greater than 75 percent of the total roof area has annual solar access that is less than 70 percent. Solar access is the ratio of solar insolation including shade to the
solar insolation without shade. Shading from obstructions located on the roof or any other part of the building shall not be included in the determination of annual solar access.
3.
Life cycle assessment compliant with Section A5.409.4 in this code may be substituted for prescriptive measures from Division A5.4.|1.
Exception: Allowance may be permitted in Tier 2 for up to 5-percent specialty purpose flooring.
2.
Solar water-heating system requirement for newly constructed restaurants as per A5.203.1.1.2.
Exceptions:
a. Buildings with a natural gas service water heater with a minimum of 95-percent thermal efficiency.
b. Buildings where greater than 75 percent of the total roof area has annual solar access that is less than 70 percent. Solar access is the ratio of solar insolation including shade to the
solar insolation without shade. Shading from obstructions located on the roof or any other part of the building shall not be included in the determination of annual solar access.
3.
Life cycle assessment compliant with Section A5.409.4 in this code may be substituted for prescriptive measures from Division A5.4.|A5.601.1 Scope. The measures contained in this appendix are not mandatory unless adopted by local government as specified in Section 101.7. The provisions of this section outline means of achieving enhanced construction or reach levels by incorporating addi
2025 CALIFORNIA GREEN BUILDING STANDARDS CODE APPENDIX A5-41
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APPENDIX A5 — NONRESIDENTIAL VOLUNTARY MEASURES
tional green building measures for newly constructed nonresidential buildings as well as additions and alterations. In order to meet one of the tier levels designers, builders or property owners are required to incorporate additional green building measures necessary to meet the threshold of each level. Refer to the provisions in Section 301.3 for nonresidential additions and alterations scope and application.
A5.601.2 CALGreen Tier 1
A5.601.2.1 Prerequisites. To achieve CALGreen tier status, a project must meet all of the mandatory measures in Chapter 5 and, in addition, meet the provisions of this section.
A5.601.2.2 Energy performance. For the purposes of mandatory energy efficiency standards in this code, the California Energy Commission will continue to adopt mandatory standards.
§ 140.9 High relevance — show source text
- In a jurisdiction where gas heating is allowed.
Exception 4 to Section 140.9(c)6: Buildings with an exhaust air heat recovery system and heat recovery chillers designed to provide at least 40 percent of the peak heating load from exhaust heat recovery.
Exception 5 to Section 140.9(c)6: Exhaust systems requiring wash down systems such as exhaust systems dedicated to perchloric acid fume hoods.
Exception to Section 140.9(c): Healthcare facilities.
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.
SECTION 140.10—PRESCRIPTIVE REQUIREMENTS FOR PHOTOVOLTAIC AND BATTERY ENERGY STORAGE SYSTEMS
(a) Photovoltaic requirements. All newly constructed building types specified in Table 140.10-A, or mixed occupancy buildings where at least 80 percent of the floor area of the building serves one or more of these building types, shall have a newly installed photovoltaic (PV) system meeting the minimum qualification requirements of Reference Joint Appendix JA11. The PV capacity in kW dc shall not be less than the smaller of the minimum rated PV system capacity determined by Equation 140.10-A, or the total of all available solar access roof areas (SARA) multiplied by 18 for steep-sloped roofs or multiplied by 14 for low-sloped roofs. In mixed occupancy buildings, the minimum rated PV system capacity for the building shall be determined by applying Equation 140.10-A to the conditioned floor area of each of the listed building types and summing the capacities determined for each.
SARA includes the area of the building’s roof space capable of structurally supporting a PV system, and the area of all roof space on covered parking areas, carports and all other newly constructed structures on the site that are compatible with supporting a PV system per Title 24, Part 2, Section 1511.10.
SARA does NOT include:
A. Any area that has less than 70 percent annual solar access. Annual solar access is determined by dividing the total annual solar insolation (accounting for shading obstructions) by the total annual solar insolation if the same areas were unshaded by those obstructions. For all roofs, all obstructions, including those that are external to the building, and obstructions that are part of the building design and elevation features may be considered for the annual solar access calculations.
B. Occupied roofs as specified by CBC Section 503.1.4. C. Roof area that is otherwise not available due to compliance with: i. Other state building code requirements; or ii. Local building code requirements if the local building code requirements are confirmed by the Executive Director.
2025 CALIFORNIA ENERGY CODE 145
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NONRESIDENTIAL AND HOTEL/MOTEL OCCUPANCIES—PERFORMANCE AND PRESCRIPTIVE
COMPLIANCE APPROACHES FOR ACHIEVING ENERGY EFFICIENCY
EQUATION 140.10-A—PHOTOVOLTAIC DIRECT CURRENT CAPACITY
kW PVdc = (CFA × A)/1000
where:
kW PVdc = Minimum rated PV system capacity in kW.
§ 110.10 High relevance — show source text
The potential solar zone area is the total area of any low-sloped roofs where the annual solar access is 70 percent or greater and any steep-sloped roofs oriented between 90 degrees and 300 degrees of true north where the annual solar access is 70 percent or greater. Solar access is the ratio of solar insolation including shade to the solar insolation without shade. Shading from obstructions located on the roof or any other part of the building shall not be included in the determination of annual solar access. Exception 5 to Section 110.10(b)1A: Single-family residences having a solar zone total area no less than 150 square feet and where all thermostats are demand responsive controls and comply with Section 110.12(a), and are capable of receiving and responding to Demand Response Signals prior to granting of an occupancy permit by the enforcing
agency. Exception 6 to Section 110.10(b)1A: Single-family residences meeting the following conditions: A. All thermostats are demand responsive controls that comply with Section 110.12(a), and are capable of receiving and responding to Demand Response Signals prior to granting of an occupancy permit by the enforcing agency. B. Comply with one of the following measures: i. Install a dishwasher that meets or exceeds the ENERGY STAR [®] Program requirements with a refrigerator that meets or exceeds the ENERGY STAR Program requirements, a whole house fan driven by an electronically commutated motor, or an SAE J1772 Level 2 Electric Vehicle Supply Equipment (EVSE or EV charger) with a minimum of 40 amperes; or ii. Install a home automation system capable of, at a minimum, controlling the appliances and lighting of the dwelling and responding to demand response signals; or iii. Install alternative plumbing piping to permit the discharge from the clothes washer and all showers and bathtubs to be used for an irrigation system in compliance with the California Plumbing Code and any applicable local ordinances; or iv. Install a rainwater catchment system designed to comply with the California Plumbing Code and any applicable local ordinances, and that uses rainwater flowing from at least 65 percent of the available roof area.
B. Multifamily buildings, hotel/motel occupancies and nonresidential buildings. The solar zone shall be located on the roof or overhang of the building or on the roof or overhang of another structure located within 250 feet of the building or on covered parking installed with the building project, and shall have a total area no less than 15 percent of the total roof area of the building excluding any skylight area. The solar zone requirement is applicable to the entire building, including mixed occupancy.
Exception 1 to Section 110.10(b)1B: High-rise multifamily buildings, hotel/motel occupancies, and nonresidential buildings with a permanently installed solar electric system having a nameplate DC power rating, measured under Standard Test Conditions, of no less than one watt per square foot of roof area.
2025 CALIFORNIA ENERGY CODE 61
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ALL OCCUPANCIES—MANDATORY REQUIREMENTS FOR THE MANUFACTURE, CONSTRUCTION AND INSTALLATION OF SYSTEMS, EQUIPMENT AND BUILDING COMPONENTS
Exception 2 to Section 110.10(b)1B: High-rise multifamily buildings, hotel/motel occupancies with a permanently installed domestic solar water-heating system complying with Section 150.1(c)8Biii.
§ 503.1.4. High relevance — show source text
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MULTIFAMILY BUILDINGS—PERFORMANCE AND PRESCRIPTIVE COMPLIANCE APPROACHES
and obstructions that are part of the building design and elevation features, may be considered for the annual solar access calculations.
B. Occupied roofs as specified by CBC Section 503.1.4. C. Roof area that is otherwise not available due to compliance with: i. Other state building code requirements, or ii. Local building code requirements if the local building code requirements are confirmed by the Executive Director.
EQUATION 170.2-D—PHOTOVOLTAIC DIRECT CURRENT CAPACITY
kW PVdc = (CFA × A)/1000
where:
kW PVdc = Minimum rated PV system capacity in kW.
CFA = Conditioned floor area in square feet.
A = PV capacity factor in W/square foot as specified in Table 170.2-U for the building type.
Exception 1 to Section 170.2(g): No PV system is required where the total of all available SARA is less than 3 percent of the conditioned floor area.
Exception 2 to Section 170.2(g): No PV system is required where the required PV system capacity is less than 4 kW dc .
Exception 3 to Section 170.2(g): No PV system is required if the SARA contains less than 80 contiguous square feet.
Exception 4 to Section 170.2(g): Buildings with enforcement-authority-approved roof designs, where the enforcement authority determines it is not possible for the PV system, including panels, modules, components, supports and attachments to the roof structure, to meet ASCE 7-16, Chapter 7, Snow Loads.
Exception 5 to Section 170.2(g): Multifamily buildings with more than three habitable stories in areas where a load-serving entity does not provide a program where PV generation is compensated through virtual energy bill credits. This exception does not apply where the Commission has approved a community solar program for showing compliance as specified in Title 24, Part 1, Section 10-115, or where a load-serving entity provides a program where PV generation is compensated through virtual energy bill credits for occupants of nonresidential and hotel/motel tenant spaces to receive energy bill benefits from netting of energy generation and consumption.
TABLE 170.2-U – PV CAPACITY FACTORS (W/ft2 of conditioned floor area) Col2 Col3 Col4 Col5 Col6 Col7 Col8 Col9 Col10 Col11 Col12 Col13 Col14 Col15 Col16 Col17 BUILDING TYPE CZ 1 CZ 2 CZ 3 CZ 4 CZ 5 CZ 6 CZ 7 CZ 8 CZ 9 CZ 10 CZ 11 CZ 12 CZ 13 CZ 14 CZ 15 CZ 16 Event & Exhibit 3.48 4.28 3.66 4.32 3.77 4.05 4.28 4.83 4.63 4.
Frequently asked questions
How do I practically compute the annual insolation ratio needed for the 70% test?
Use annual‑resolved insolation modeling (PV shading/irradiance tools or annual ray‑trace) to get total annual kWh/m² (or Wh/ft²) for the area with existing obstructions and for the same area unshaded; divide shaded by unshaded. The code requires an annual ratio — see § 140.10(a) and § 170.2(f).
For multifamily steep roofs, which obstructions are allowed to be counted?
For steep‑sloped multifamily roofs the code limits considered obstructions to existing permanent natural or manmade obstructions that are external to the dwelling (examples: trees, hills, adjacent structures). See § 170.2(f).
If a roof area is partially shaded, can I include the unshaded portion?
Yes — apply the annual solar access calculation to the actual candidate area. If the area as analyzed meets ≥ 70% annual access it can be included in SARA. If not, that portion is excluded. See § 140.10(a) and § 170.2(f).
Do roof‑mounted vents or equipment always count as obstructions to exclude area?
Treatment depends on the applicable section: § 140.10(a) allows considering all obstructions; § 170.2(f) treats steep vs low roofs differently. Also separate solar‑zone rules (§ 110.10) place additional limits on locating obstructions in a solar zone. Check the applicable occupancy section(s).
What are the main exemptions that can remove the PV requirement entirely?
Examples in the code: total available SARA < 3% of CFA, required PV < 4 kW dc, or SARA < 80 contiguous ft² — see exceptions in § 140.10(a) and § 170.2(f).
More in California Energy Code
- Compliance paths, energy budgets, performance modeling and forms/software requirements
- Controls, commissioning, demand-response, sensors, and field verification/diagnostic testing
- Domestic hot water systems, efficiency, controls and installation requirements
- Electrical infrastructure, EV charging readiness, load management and demand controls
- Envelope construction, insulation, fenestration and thermal performance
- HVAC systems, ventilation rates, ducting, controls and testing
- Interior and exterior lighting power, controls and daylighting requirements
- Mandatory measures, appliance efficiency and certification requirements
- Photovoltaic requirements, BESS (battery energy storage) sizing and SARA procedures
- Reference appendices, test procedures, product certification and labeling requirements
- Scope, applicability, definitions and administrative requirements
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