Title 24 · California Energy Code
BESS exceptions, minimum thresholds, and mixed‑occupancy rules
If your building is required to have PV, the California Energy Code generally requires a BESS sized by the code equations — but you can skip BESS if your installed PV is under 15% of the required PV or if the computed minimum BESS energy is under 10 kWh; multitenant buildings only count tenant spaces over 5,000 sq ft when sizing BESS.
Last reviewed: July 6, 2026
What the code requires — plain English
All buildings that the code requires to have a photovoltaic (PV) system must also provide a battery energy storage system (BESS) sized to the minimum rated usable energy capacity and power capacity specified by the code. The sizing is computed with the BESS equations in § 140.10(b) (nonresidential/hotel) and for taller multifamily buildings in § 170.2(h); mixed‑occupancy buildings must size BESS by applying the per‑occupancy formulas and summing the results.
The single most important rule: if the building’s installed PV is very small relative to the PV required, or the computed minimum BESS energy is tiny, the code explicitly says “no BESS required.” See § 140.10(b) Exceptions 1–3 and § 170.2(h) Exceptions 1–2.
(Defined terms bolded on first mention: BESS, PV, SARA, Minimum Rated Usable Energy Capacity, Minimum Power Capacity, mixed occupancy, multitenant.)
Requirements in detail
What to size and what equations apply
- Minimum rated usable energy capacity: calculated using Equation 140.10‑B (or 140.10‑C when SARA/SARA‑adjusted PV sizing was used) for the nonresidential/hotel/motel provisions. § 140.10(b) requires this sizing method.
- Minimum rated power capacity: determined using Equation 140.10‑D (kW batt = kW batt / 4 — see the code for the exact variable names). § 140.10(b).
- For multifamily buildings more than three stories, the equivalent requirements and equations are in § 170.2(h) (Equations 170.2‑E/F and 170.2‑G).
- For mixed occupancy (any building containing two or more listed building types), the rule is: calculate the minimum rated usable energy capacity for each listed building type (using the appropriate CFA and B factor) and sum them to determine the total BESS capacity required for the building. This rule is stated in both § 140.10(b) and § 170.2(h).
Decision‑relevant thresholds and values
| Decision dimension | Value / threshold | How it changes the requirement | Code Reference |
|---|---|---|---|
| PV installed vs required (no‑BESS test) | 15% — installed PV < 15% of capacity from Equation 140.10‑A (or 170.2‑D for multifamily) | If installed PV is less than 15% of the required PV, no BESS is required (Exception 1). | § 140.10(b) Exception 1 ; § 170.2(h) Exception 1 |
| Minimum rated usable energy capacity (no‑BESS test) | 10 kWh | If the computed minimum rated usable energy capacity (Equation 140.10‑B/C or 170.2‑E/F) is less than 10 kWh, no BESS is required (Exception 2). | § 140.10(b) Exception 2 ; § 170.2(h) Exception 2 |
| Tenant space area that counts for BESS in multitenant | 5,000 square feet | For multitenant buildings: the BESS energy capacity is based on tenant spaces with more than 5,000 sq ft CFA; single‑tenant buildings with less than 5,000 sq ft are exempt (Exception 3 to § 140.10(b)). | § 140.10(b) Exception 3 |
| Mixed‑occupancy calculation method | Per‑occupancy CFA × B ÷ (1000 × C^0.5) (or SARA‑adjusted variant) | Compute each listed occupancy’s minimum kWh using the applicable equation, then sum them for the building total. | § 140.10(b) and § 170.2(h) |
Notes:
- The code provides the exact equations (Equations 140.10‑B/C/D and 170.2‑E/F/G) and the BESS capacity factors (B) in tables referenced by those sections. Use the tables and the round‑trip efficiency parameter C as shown in the code when performing calculations.
Exceptions & special cases
Exception 1 (PV too small) — If the building's actually installed PV capacity is less than 15% of the PV capacity the code would otherwise require (Equation 140.10‑A or 170.2‑D), no BESS is required. This is a direct exemption and applies both to the § 140.10(b) regime and the § 170.2(h) multifamily regime.
Exception 2 (tiny computed BESS) — If the calculated minimum rated usable energy capacity from the applicable equation is less than 10 kWh, no BESS is required. This prevents very small BESS requirements.
Exception 3 (multitenant area threshold) — For multitenant nonresidential buildings the energy capacity calculation is based on tenant spaces with > 5,000 sq ft CFA. Also, for single‑tenant buildings under 5,000 sq ft CFA, no BESS is required. (This is Exception 3 to § 140.10(b).) Note: other PV exceptions (e.g., PV sizing exclusions for small tenant spaces under § 140.10(a) Exception 5) use different area thresholds — do not confuse the two.
Mixed occupancy — If a building contains multiple listed building types, the code requires you to apply the per‑type sizing method to each type’s conditioned floor area and sum the outcomes to get the total BESS capacity for the building (this appears in both § 140.10(b) and § 170.2(h)).
SARA adjustments and SARA‑adjusted equations — If SARA (solar access roof area) was used for PV sizing, use the SARA‑adjusted BESS equation (Equation 140.10‑C or 170.2‑F) as the code prescribes.
Common mistakes
Treating the 15% test as 15% of installed system vs. required system interchangeably without referencing the required PV from Equation 140.10‑A (or 170.2‑D). The exemption compares installed PV to the capacity determined by the equation (not to some other installed or nameplate value).
Confusing the 5,000 sq ft threshold in § 140.10(b) Exception 3 (BESS/tenant counting) with the 2,000 sq ft threshold that appears in the PV tenant‑space exclusion to PV sizing under § 140.10(a) Exception 5. They serve different purposes and are different limits. Check the correct section before deciding whether a tenant’s area should be excluded or included.
Forgetting to use the SARA‑adjusted equation when PV capacity was reduced by SARA (Equation 140.10‑C or 170.2‑F). If you used SARA to compute PVdc, you must use the SARA variant to compute the BESS energy requirement.
Omitting the mixed‑occupancy summation step: the code requires per‑occupancy computations and adding them for mixed buildings — you cannot simply compute a single BESS using a blended CFA without following the specified method.
Worked example — concrete decision flow with numbers
Scenario A — quick “no‑BESS” determination using the 15% test:
- Equation 140.10‑A (PV sizing) yields a required PV capacity of 100 kWdc for the building. (This is the required PV from the code calculation.)
- The building owner installs 12 kWdc of PV on site. Installed/required = 12 / 100 = 12%, which is less than 15%.
Result: Under § 140.10(b) Exception 1, no BESS is required.
Scenario B — tiny computed BESS energy (<10 kWh):
- Using Equation 140.10‑B (or 140.10‑C if SARA was used), the designer computes the building’s minimum rated usable energy capacity and obtains 8 kWh.
Result: Because 8 kWh is less than 10 kWh, § 140.10(b) Exception 2 says no BESS is required.
Scenario C — multitenant mixed‑occupancy summation:
- Building has two tenant spaces: Tenant A = 6,200 sq ft CFA (restaurant); Tenant B = 4,200 sq ft CFA (retail).
- Under § 140.10(b) Exception 3, only tenants with more than 5,000 sq ft are counted for the BESS energy capacity calculation. Tenant A counts; Tenant B does not.
- The designer applies Equation 140.10‑B to Tenant A’s CFA (and the correct B value for the restaurant occupancy from the code’s table) to compute Tenant‑A kWh. That kWh (plus zero from Tenant B) is the building’s minimum rated usable energy capacity to compare to 10 kWh or to determine the required BESS size. (Follow the exact arithmetic in Equation 140.10‑B/C and the referenced tables from the code.)
(If you want me to compute the numeric kWh for Tenant A here, tell me the climate zone and I will pull the proper BESS capacity‑factor B and the BESS efficiency C from the tables in the code and show the arithmetic step‑by‑step.)
Related provisions
- § 140.10(a) — PV requirement framework and Equation 140.10‑A (used as the PV capacity reference for the 15% BESS exception).
- § 140.10(b) — BESS requirement statement, equations 140.10‑B/C/D, and Exceptions 1–3 (primary nonresidential BESS text).
- § 170.2(g) — PV requirements for multifamily buildings more than three stories (feeds into § 170.2(h)).
- § 170.2(h) — BESS requirements, equations 170.2‑E/F/G, and Exceptions 1–2 for multifamily >3 stories.
- Reference Joint Appendix JA12 — BESS qualification requirements (equipment qualification and minimum cycling definitions referenced by § 140.10(b) and § 170.2(h)).
Code references
Grounded in the retrieved California Energy Code — click a citation to read the verbatim passage:
§ 140.10 High relevance — show source text
(b) Battery energy storage system (BESS) requirements. All buildings that are required by Section 140.10(a) to have a PV system shall also have a BESS meeting the minimum qualification requirements of Reference Joint Appendix JA12. The rated energy capacity shall be not less than the Minimum Rated Useable Energy Capacity determined using Equation 140.10-B or 140.10-C if SARA was used to determine the PV capacity in Section 140.10(a). The rated power capacity shall be not less than the Minimum Power Capacity determined using Equation 140.10-D. In mixed occupancy buildings, the total battery system capacity for the building shall be determined by applying the Minimum Rated Usable Energy Capacity to each of the listed building types and summing the capacities determined for each.
EQUATION 140.10-B—BATTERY ENERGY STORAGE SYSTEM MINIMUM RATED USABLE ENERGY CAPACITY kWh batt = [(CFA × B)/(1,000 × C [0.5] )]
EQUATION 140.10-C—BATTERY ENERGY STORAGE SYSTEM MINIMUM RATED USABLE ENERGY CAPACITY, SARA-ADJUSTED kWh batt = [(CFA × B)/(1,000 × C [0.5] )] x (kW PVdc,SARA /kW PVdc )
where:
kWh batt = Minimum Rated Usable Energy Capacity of the BESS in kWh.
CFA = Conditioned floor area that is subject to the PV system requirements of Section 140.10(a) in square feet.
kW PVdc = Minimum Rated PV System Capacity in kW from Equation 140.10-A. kW PVdc, SARA = Minimum Rated PV System Capacity in kW from the SARA calculation. B = BESS Capacity Factor in Wh/square foot as specified in Table 140.10-B for the building type. C = Rated single charge-discharge cycle AC to AC (round-trip) efficiency of the BESS.
EQUATION 140.10-D—BESS MINIMUM RATED POWER CAPACITY
kW batt = kW batt /4
where:
kW batt = Minimum Rated Power Capacity of the BESS in kWdc. kW PVdc = Minimum Rated Useable Energy Capacity of the BESS in kWh. Exception 1 to Section 140.10(b): No BESS is required if the installed PV system capacity is less than 15 percent of the capacity determined by Equation 140.10-A.
Exception 2 to Section 140.10(b): No BESS is required if the rated usable energy capacity determined by Equation 140.10-B or Equation 140.10-C is less than 10 kWh.
Exception 3 to Section 140.10(b): For multitenant buildings, the energy capacity of the BESS shall be based on the tenant spaces with more than 5,000 square feet of conditioned floor area. For single-tenant buildings with less than 5,000 square feet of conditioned floor area, no BESS is required.
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|TABLE 140.
§ 140.10 High relevance — show source text
EQUATION 140.10-D—BESS MINIMUM RATED POWER CAPACITY
kW batt = kW batt /4
where:
kW batt = Minimum Rated Power Capacity of the BESS in kWdc. kW PVdc = Minimum Rated Useable Energy Capacity of the BESS in kWh. Exception 1 to Section 140.10(b): No BESS is required if the installed PV system capacity is less than 15 percent of the capacity determined by Equation 140.10-A.
Exception 2 to Section 140.10(b): No BESS is required if the rated usable energy capacity determined by Equation 140.10-B or Equation 140.10-C is less than 10 kWh.
Exception 3 to Section 140.10(b): For multitenant buildings, the energy capacity of the BESS shall be based on the tenant spaces with more than 5,000 square feet of conditioned floor area. For single-tenant buildings with less than 5,000 square feet of conditioned floor area, no BESS is required.
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TABLE 140.10-A—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** Events & Exhibits 3.48 4.28 3.66 4.32 3.77 4.05 4.28 4.83 4.63 4.80 5.04 4.44 4.95 4.36 5.48 3.38 Library 0.39 3.23 2.59 3.25 2.48 2.74 3.04 3.49 3.32 3.69 3.79 3.32 3.79 3.37 4.49 2.84 Hotel/Motel 1.69 1.90 1.66 1.97 1.69 1.87 1.94 2.22 2.09 2.20 2.30 2.05 2.30 2.02 2.72 1.73 Office, Financial
Institution, Unleased
Tenant Space, Medical
Office Building/Clinic2.59 3.13 2.59 3.13 2.59 3.13 3.13 3. § 170.2 High relevance — show source text
The rated energy capacity shall be not less than the Minimum Rated Useable Energy Capacity determined by Equation 170.2-E, or by Equation 170.2-F if SARA was used to determine the PV capacity in Section 170.2-D, and the rated power capacity shall be not less than the Minimum Power Capacity determined by Equation 170.2-G. In mixed occupancy buildings, the total battery system capacity for the building shall be determined by applying the Minimum Rated Usable Energy Capacity to each of the listed building types and summing the capacities determined for each.
EQUATION 170.2-E—BATTERY ENERGY STORAGE SYSTEM MINIMUM RATED USABLE ENERGY CAPACITY kWh batt = k((CFA × B)/(1000 × C [0.5] ))
— EQUATION 170.2-F BATTERY ENERGY STORAGE SYSTEM MINIMUM RATED USABLE ENERGY CAPACITY, SARA-ADJUSTED kWh batt = k((CFA × B)/(1000 × C [0.5] )) × (kWP Vdc,SARA /kWP Vdc )
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where:
kWh batt = Minimum Rated Usable Energy Capacity of the BESS in kWh.
kW PVdc = Minimum Rated PV System Capacity in kW from Equation 170.2D. kW PVdc, SARA = Minimum Rated PV System Capacity in kW from the SARA calculation. CFA = Conditioned floor area that is subject to the PV system requirements of Section 170.2(g) in square feet.
B = BESS Capacity Factor in Wh/square foot as specified in Table 170.2-V for the building type.
C = Rated single charge-discharge cycle AC to AC (round-trip) efficiency of the BESS.
EQUATION 170.2-G—BATTERY ENERGY STORAGE SYSTEM MINIMUM RATED POWER CAPACITY
kW batt = kW batt /4
where:
kW batt = Minimum Rated Power Capacity of the BESS in kW dc .
kWh batt = Minimum Rated Usable Energy Capacity of the BESS in kWh.
Exception 1 to Section 170.2(h): No BESS is required if the installed PV system capacity is less than 15 percent of the capacity determined by Equation 170.2-D.
Exception 2 to Section 170.2(h): No BESS is required in buildings with BESS requirements with less than 10 kWh minimum rated usable energy capacity.
|TABLE 170.
§ 140.10 High relevance — show source text
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.
(b) Battery energy storage system (BESS) requirements. All buildings that are required by Section 140.10(a) to have a PV system shall also have a BESS meeting the minimum qualification requirements of Reference Joint Appendix JA12. The rated energy capacity shall be not less than the Minimum Rated Useable Energy Capacity determined using Equation 140.10-B or 140.10-C if SARA was used to determine the PV capacity in Section 140.10(a). The rated power capacity shall be not less than the Minimum Power Capacity determined using Equation 140.10-D. In mixed occupancy buildings, the total battery system capacity for the building shall be determined by applying the Minimum Rated Usable Energy Capacity to each of the listed building types and summing the capacities determined for each.
EQUATION 140.10-B—BATTERY ENERGY STORAGE SYSTEM MINIMUM RATED USABLE ENERGY CAPACITY kWh batt = [(CFA × B)/(1,000 × C [0.5] )]
EQUATION 140.10-C—BATTERY ENERGY STORAGE SYSTEM MINIMUM RATED USABLE ENERGY CAPACITY, SARA-ADJUSTED kWh batt = [(CFA × B)/(1,000 × C [0.5] )] x (kW PVdc,SARA /kW PVdc )
where:
kWh batt = Minimum Rated Usable Energy Capacity of the BESS in kWh.
CFA = Conditioned floor area that is subject to the PV system requirements of Section 140.10(a) in square feet.
§ 170.2 High relevance — show source text
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where:
kWh batt = Minimum Rated Usable Energy Capacity of the BESS in kWh.
kW PVdc = Minimum Rated PV System Capacity in kW from Equation 170.2D. kW PVdc, SARA = Minimum Rated PV System Capacity in kW from the SARA calculation. CFA = Conditioned floor area that is subject to the PV system requirements of Section 170.2(g) in square feet.
B = BESS Capacity Factor in Wh/square foot as specified in Table 170.2-V for the building type.
C = Rated single charge-discharge cycle AC to AC (round-trip) efficiency of the BESS.
EQUATION 170.2-G—BATTERY ENERGY STORAGE SYSTEM MINIMUM RATED POWER CAPACITY
kW batt = kW batt /4
where:
kW batt = Minimum Rated Power Capacity of the BESS in kW dc .
kWh batt = Minimum Rated Usable Energy Capacity of the BESS in kWh.
Exception 1 to Section 170.2(h): No BESS is required if the installed PV system capacity is less than 15 percent of the capacity determined by Equation 170.2-D.
Exception 2 to Section 170.2(h): No BESS is required in buildings with BESS requirements with less than 10 kWh minimum rated usable energy capacity.
TABLE 170.2-V—BESS CAPACITY FACTORS (Wh/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 1.82 1.95 1.74 2.12 1.91 2.13 2.24 2.30 2.36 2.47 2.62 2.16 2.64 2.68 3.22 1.89 Library 0.37 7.17 5.97 6.75 5.64 6.08 6.19 7.13 7.18 7.56 7.17 6.93 6.88 6.81 7.93 6.40 Hotel/Motel 0.86 0.84 0.77 0.92 0.81 0.89 0.90 1.01 1.00 1.11 1.14 0.96 1.18 1.18 1.49 0.85 Office, Financial Institution, § 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,
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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.
§ 1.27 High relevance — show source text
63|1.27|1.63|1.27|1.63|1.63|1.63|1.63|1.63|1.63|1.63|1.63|1.63|2.46|1.27| |Warehouse|0.39|0.44|0.39|0.44|0.39|0.44|0.44|0.44|0.44|0.44|0.44|0.44|0.44|0.44|0.58|0.39| |Religious Worship|4.25|4.65|3.49|4.52|3.72|4.29|4.64|5.89|5.30|5.67|5.89|4.99|5.78|4.63|7.57|3.90| |Sports & Recreation|2.47|1.97|1.54|2.03|1.60|1.84|1.98|2.63|2.47|2.60|2.75|2.20|2.72|2.15|4.03|1.81| |Multifamily > 3 stories|1.82|2.21|1.82|2.21|1.82|2.21|2.21|2.21|2.21|2.21|2.21|2.21|2.21|2.21|2.77|1.82|
(h) Battery energy storage system (BESS) requirements—more than three habitable stories. All buildings that are required by Section 170.2(g) to have a PV system shall also have a BESS meeting the minimum qualification requirements of Reference Joint Appendix JA12. The rated energy capacity shall be not less than the Minimum Rated Useable Energy Capacity determined by Equation 170.2-E, or by Equation 170.2-F if SARA was used to determine the PV capacity in Section 170.2-D, and the rated power capacity shall be not less than the Minimum Power Capacity determined by Equation 170.2-G. In mixed occupancy buildings, the total battery system capacity for the building shall be determined by applying the Minimum Rated Usable Energy Capacity to each of the listed building types and summing the capacities determined for each.
EQUATION 170.2-E—BATTERY ENERGY STORAGE SYSTEM MINIMUM RATED USABLE ENERGY CAPACITY kWh batt = k((CFA × B)/(1000 × C [0.5] ))
— EQUATION 170.2-F BATTERY ENERGY STORAGE SYSTEM MINIMUM RATED USABLE ENERGY CAPACITY, SARA-ADJUSTED kWh batt = k((CFA × B)/(1000 × C [0.5] )) × (kWP Vdc,SARA /kWP Vdc )
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where:
kWh batt = Minimum Rated Usable Energy Capacity of the BESS in kWh.
kW PVdc = Minimum Rated PV System Capacity in kW from Equation 170.2D. kW PVdc, SARA = Minimum Rated PV System Capacity in kW from the SARA calculation. CFA = Conditioned floor area that is subject to the PV system requirements of Section 170.2(g) in square feet.
§ 170.0 Medium relevance — show source text
Exception to Section 170.0 (a)3: If a single development falls in more than one climate zone, all buildings in the subdivision or tract may be designed to meet the performance or prescriptive standards for the climate zone that contains 50 percent or more of the dwelling units.
NOTE: The Commission periodically updates, publishes and makes available to interested persons and local enforcement agencies precise descriptions of the climate zones, as specified in Reference Joint Appendix JA2—Weather/Climate Data.
NOTE: The requirements of Sections 170.1(a) through 170.2(e) apply to newly constructed buildings and Sections 180.1 and 180.2 specify changes to the requirements of Sections 170.1(a) through 170.2(e) that apply to additions or alterations.
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 170.1—PERFORMANCE APPROACH
A building complies with the performance approach if the energy consumption calculated for the proposed design building is no greater than the energy budget calculated for the standard design building using Commission-certified compliance software as specified by Sections 10-109 and 10-116 and the Alternative Calculation Method Reference Manual.
(a) Energy budget. The energy budget is expressed in terms of long-term system cost (LSC) and source energy:
- Long-term system cost (LSC). The LSC energy budget is determined by applying the mandatory and prescriptive requirements of the standard design to the proposed design building and has two components, the Efficiency LSC and the Total LSC.
A. The Efficiency LSC energy is the sum of the LSC energy for space-conditioning, water heating, mechanical ventilation, lighting and the self-utilization credit. B. The Total LSC energy is the sum of the Efficiency LSC energy and LSC energy from the photovoltaic system, battery energy storage systems (BESS), and demand flexibility. 2. Source energy. The source energy budget is determined by applying the mandatory and prescriptive requirements of the standard design, except with a consumer gas or propane water heater, to the proposed design building.
Exception to Section 170.1(a): A community shared solar electric generation system, or other renewable electric generation system, and/or community shared BESS, that provides dedicated power, utility energy reduction credits or payments for energy bill reductions to the permitted building and is approved by the Energy Commission as specified in Title 24, Part 1, Section 10-115, may offset part or all of the solar electric generation system or BESS LSC energy required to comply with the standards, as calculated according to methods established by the Commission in the Nonresidential ACM Reference Manual.
(b) Compliance demonstration requirements for performance standards.
- Certificate of Compliance and Application for a Building Permit. The application for a building permit shall include documentation pursuant to Sections 10-103(a)1 and 10-103(a)2 that demonstrates, using an approved calculation method, that the building has been designed so that its source energy and LSC energy consumption do not exceed the standard design energy budgets for the applicable climate zone.
- Field verification of individual dwelling unit systems.
§ 4.44 Medium relevance — show source text
04|4.44|4.95|4.36|5.48|3.38| |Library|0.39|3.23|2.59|3.25|2.48|2.74|3.04|3.49|3.32|3.69|3.79|3.32|3.79|3.37|4.49|2.84| |Hotel/Motel|1.69|1.90|1.66|1.97|1.69|1.87|1.94|2.22|2.09|2.20|2.30|2.05|2.30|2.02|2.72|1.73| |Office, Financial Institution,
Unleased Tenant Space,
Medical Office Building/Clinic|2.59|3.13|2.59|3.13|2.59|3.13|3.13|3.13|3.13|3.13|3.13|3.13|3.13|3.13|3.80|2.59| |Restaurant|8.55|9.32|8.16|9.65|8.21|8.73|9.11|10.18|9.75|10.28|10.85|9.73|10.69|9.73|12.25|8.47| |Retail, Grocery|3.14|3.49|3.01|3.61|3.05|3.27|3.45|3.83|3.65|3.81|4.09|3.64|3.99|3.71|4.60|3.21| |School|1.27|1.63|1.27|1.63|1.27|1.63|1.63|1.63|1.63|1.63|1.63|1.63|1.63|1.63|2.46|1.27| |Warehouse|0.39|0.44|0.39|0.44|0.39|0.44|0.44|0.44|0.44|0.44|0.44|0.44|0.44|0.44|0.58|0.39| |Religious Worship|4.25|4.65|3.49|4.52|3.72|4.29|4.64|5.89|5.30|5.67|5.89|4.99|5.78|4.63|7.57|3.90| |Sports & Recreation|2.47|1.97|1.54|2.03|1.60|1.84|1.98|2.63|2.47|2.60|2.75|2.20|2.72|2.15|4.03|1.81| |Multifamily > 3 stories|1.82|2.21|1.82|2.21|1.82|2.21|2.21|2.21|2.21|2.21|2.21|2.21|2.21|2.21|2.77|1.82|(h) Battery energy storage system (BESS) requirements—more than three habitable stories. All buildings that are required by Section 170.2(g) to have a PV system shall also have a BESS meeting the minimum qualification requirements of Reference Joint Appendix JA12.
California Energy Code Medium relevance — show source text
The audible alarm circuit shall be continuous to the terminals of the relay approved for alarm signaling service for the control unit, except that contacts of a combination signaling system power-supply supervisory relay may be included in the circuit. 4. The alarm signal relay shall be firmly attached to the enclosure and shall be a component part of the combination signaling system unit. 5. The interconnection between control units having nonsupervised audible alarm circuits and the combination signaling system shall be in duplicate, connected alternately to two or more signal relays wired in parallel to the oscillator or tone signal relays. 6. Portions of alarm circuits in combination signaling system control panels which are not supervised from the contacts of the audible alarm signal relay to the oscillator or tone signal alarm relays shall not exceed 24 inches (609 mm) in length. They shall be of 600V insulated wire held in place by clamps or equivalent and so located that they will not be subject to handling during use or servicing.
(o) Capacitors. Capacitors shall be of materials suitable for their intended use. A paper capacitor shall be impregnated or suitably enclosed to exclude moisture. It shall not be injuriously affected by the temperature attained under the most severe conditions of use. The removal of a capacitor of the plug-in type shall require the use of a tool.
(p) Coil windings—transformers.
The insulation of coil windings of relays, transformers, etc., shall be impregnated or otherwise designed to exclude moisture.
Transformers connected across a power-supply circuit shall be individually housed in noncombustible material.
Transformers shall be of the two-coil or insulated type except that an autotransformer may be employed provided the terminal common to both input and output circuits is connected to the grounded supply terminal.
(q) Overcurrent protection.
- Storage batteries provided as part of a control unit, other than primary batteries, shall be protected by overcurrent devices having a rating of not less than 150 percent and not more than 200 percent of the maximum operating load on the battery.
- System control units and combination signaling system control units shall be protected on the current supply side by overcurrent devices having a rating not more than 150 percent of the maximum normal operating current.
- Transformers shall be protected on either the primary or secondary side by overcurrent devices having a rating not greater than the continuous duty rating of the transformer unless the current is limited to the same value by other acceptable
means.
(r) Rectifiers.
- Rectifiers used direct shall be approved for the purpose and of adequate capacity to maintain voltage regulation between 100 percent of rated voltage at maximum load and 130 percent of rated voltage at no load.
- A control unit incorporating a battery-charging rectifier shall be provided with meters as part of the assembly or with readily accessible terminal connections for portable meters for determination of battery voltage and charging current.
(s) Storage batteries.
- Storage batteries provided as part of a control unit shall have sealed cells with spray-trap vents. Normal charging shall be by a trickle-charge rectifier. The mounting arrangement shall prevent terminals from contacting terminals of adjacent cells or parts of the battery enclosure. The cells shall permit ready access for checking the specific gravity of the electrolyte.
- The conditioning charge shall be so limited that with the maximum charge which can be obtained, the battery gases will not adversely affect the control unit.
§ 1207.5.1 Medium relevance — show source text
For electrochemical ESS units rated in amp-hours, kWh shall equal rated voltage times the amp-hour rating divided by 1,000.
b. Shall include vanadium, zinc-bromine, polysulfide-bromide and other flowing electrolyte-type technologies.|1207.5.1 Size and separation. Electrochemical ESS shall be segregated into groups not exceeding 50 kWh (180 megajoules). Each group shall be separated a minimum of 3 feet (914 mm) from other groups and from walls in the storage room or area. The storage arrangements shall comply with Chapter 10.
Exceptions: (Material based on NFPA 855 2023 Ed.)
Lead-acid and nickel-cadmium battery systems in facilities under the exclusive control of communications utilities and operating at less than 50 VAC and 60 VDC in accordance with NFPA 76.
Lead-acid and nickel-cadmium systems that are used for DC power for control of substations and control or safe shutdown of generating stations under the exclusive control of the electric utility, and located outdoors or in building spaces used exclusively for such installations.
Lead-acid battery systems in uninterruptable power supplies listed and labeled in accordance with UL 1778, utilized for standby power applications, and limited to not more than 10 percent of the floor area on the floor on which the ESS is located.
The fire code official is authorized to approve larger capacities or smaller separation distances based on large-scale fire testing complying with Section 1207.1.5.
1207.5.2 Maximum allowable quantities. Fire areas within rooms, areas and walk-in units containing electrochemical ESS shall not exceed the maximum allowable quantities in Table 1207.5.
Exceptions: (Material based on NFPA 855 2023 Ed.)
- Where approved by the fire code official, rooms, areas and walk-in units containing electrochemical ESS that exceed the amounts in Table 1207.5 shall be permitted based on a hazardous mitigation analysis in accordance with Section 1207.1.6 and large-scale fire testing complying with Section 1207.1.7.
- Lead-acid and nickel-cadmium battery systems installed in facilities under the exclusive control of communications utilities, and operating at less than 50 VAC and 60 VDC in accordance with NFPA 76.
2025 CALIFORNIA FIRE CODE 12-15
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
ENERGY SYSTEMS
- Dedicated-use buildings in compliance with Section 1207.7.1.
1207.5.2.1 Mixed electrochemical energy systems. Where rooms, areas and walk-in units contain different types of electrochemical energy technologies, the total aggregate quantities of the systems shall be determined based on the sum of percentages of each technology-type quantity divided by the maximum allowable quantity of each technology type. The sum of the percentages shall not exceed 100 percent of the maximum allowable quantity.
1207.5.3 Elevation. Electrochemical ESS shall not be located in the following areas:
- Where the floor is located more than 75 feet (22 860 mm) above the lowest level of fire department vehicle access.
- Where the floor is located below the lowest level of exit discharge.
Exceptions: (Material based on NFPA 855 2023 Ed.)
- Lead-acid and nickel-cadmium battery systems less than 50 VAC and 60 VDC installed in facilities under the exclusive control of communications utilities in accordance with NFPA 76.
§ 110.10 Medium relevance — show source text
Main Electrical Service Panel 110.10(e), 150.0(n)1B, 150.0(t–v), 160.9(a–c) Makeup Air 120.1(c)1A, 120.1(c)4, 140.9(b)2, 140.9(c)1, 150.0(m)12A, 150.0(o)1K, 160.2(b)1, 160.2(b)2A, 160.2(c)1, 160.2(c)4, 170.2(c)4N Malls 120.2(e), 130.1(a)2, 130.1(c) Mandatory Indoor lighting 130.1, 160.5(b)4 Insulation 120.7, 150.0(a)2, 160.1(a)1A Measures 100.0(e), 100.0(f), 140.0(a), 140.0(b) Mandatory Requirements For the manufacture, construction and installation of systems, equipment and building components 110.0–110.12 Nonresidential, hotel/motel occupancies, and covered processes 120.0–120.10
Nonresidential, hotel/motel occupancies: for lighting systems and equipment and electrical power distribution systems 130.0–130.5 Nonresidential, hotel/motel additions 141.0(b) Single family residential buildings 150.0 Multifamily buildings 160.0–160.9, 170.2(e), 180.2(a)
312 2025 CALIFORNIA ENERGY CODE
on Jul 18, 2025 11:14 AM (CDT) THEREUNDER.
INDEX
Minimum Ventilation Rates for Multifamily Common Use Areas Table 160.2-b Mixed Occupancy Building 160.0 Moderate Contaminant 120.1(G)2, 160.2(C)8 Moisture 110.8(G)2, 120.3(B), 120.4(F), 150.0(M)9, 160.3(B)5i, 160.3(C)1c, 160.3(C)2g, 160.4(F)2 More Than Three Habitable Stories 170.2(G), 170.2(H) Motor 110.10(B)1b, 120.6(A)5d, 120.6(A), 120.6(D), 120.6(J)3, 120.9(B), 140.4(C)3, 140.4(H)1, Table 140.4-i, 160.4(E), 170.2(C)4 Efficiency 120.6(A)3a, 140.4(C)3, 170.2(C)4 Horsepower 140.4(K)6, 170.2(C)4i Nameplate Table 110.2-f, 120.10(A), 140.4(C)1, Table 140.4-d, 170.2(B)4a, Table 170.2-e-1 Motorized Damper 150.0(O), 160.2(B)2a Movie Theater 140.3(C) Moving Walkway 120.6(G) Multifamily Table 100.0-a, 110.10(A), 110.10(B)1b, Table 140.10-a,
Frequently asked questions
When can I skip installing a BESS?
If the building’s installed PV is less than 15% of the PV capacity the code would require (Equation 140.10‑A or 170.2‑D), or if the computed minimum rated usable energy is less than 10 kWh, the code provides explicit “no BESS required” exceptions. § 140.10(b) Exceptions 1–2 and § 170.2(h) Exceptions 1–2.
How do I handle a mixed‑use building with several occupancies?
Calculate the minimum rated usable energy separately for each listed building type using the applicable equation and B factor, then sum the per‑type results to get the building’s required BESS capacity (this rule is in § 140.10(b) and § 170.2(h)).
Does a 2,000 sq ft tenant exemption for PV also apply to BESS?
No. The PV tenant exclusion under § 140.10(a) Exception 5 uses 2,000 sq ft for PV capacity calculation, but the BESS multitenant threshold is 5,000 sq ft under § 140.10(b) Exception 3. They are separate rules and thresholds.
If I used SARA to reduce PV capacity, do I change the BESS equation?
Yes. When SARA was used for PV (the SARA adjustment), use the SARA‑adjusted BESS equation (Equation 140.10‑C or 170.2‑F) as the code requires.
Where are the qualification/installation details for BESS equipment?
The code references Reference Joint Appendix JA12 for BESS qualification requirements (listed by § 140.10(b) and § 170.2(h)). The sizing rules here do not replace the JA12 qualification/installation requirements.
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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