Title 24 · California Energy Code

Battery Energy Storage System (BESS) sizing and capacity rules

Title 24 Part 6 prescribes minimum BESS energy and power sizing (via Equations 140.10‑B/C/D and 170.2‑E/F/G and their tables), qualification requirements, and specific exceptions.

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Last reviewed: July 6, 2026

Overview

This part of the California Energy Code sets mandatory minimum sizing and power-capacity rules for stationary battery energy storage systems (BESS) paired with required on-site photovoltaics. For many nonresidential and hotel/motel buildings the code prescribes a minimum rated usable energy capacity and a minimum power capacity calculated from the building conditioned floor area, a BESS “capacity factor,” and the BESS round‑trip efficiency using the formulas in § 140.10 (Equations 140.10‑B, 140.10‑C and 140.10‑D) and related tables; BESS must also meet the qualification requirements in Reference Joint Appendix JA12 .

Multifamily high‑rise and other occupancy‑specific branches use analogous equations and tables (for example § 170.2(h) with Equations 170.2‑E, 170.2‑F and 170.2‑G and Table 170.2‑V) to produce the building’s minimum kWh and kW requirements; the code treats mixed occupancies by summing capacities calculated for each listed building type . The standards also include clear exceptions (for example no BESS where the required PV is less than 15% of the calculated PV capacity, or where the computed minimum energy capacity is under 10 kWh) and specify how to adjust for SARA (solar access) calculations and the BESS round‑trip efficiency when computing required sizes .

Key cross‑references and definitions you’ll use when applying these rules include the BESS definition and BESS‑ready interconnection equipment in the code’s definitions and the capacity‑factor tables that drive the equations; those definitions and terms are in the Title 24 Part 6 materials and appended reference tables used by the formulas .

In this section

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.

  • § 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.

  • § 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/Clinic    		 2.59 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.

  • § 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,
  • § 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.

  • § 170.0 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:

    1. 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.

    1. 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.
    2. Field verification of individual dwelling unit systems.
  • § 140.0 Medium relevance — show source text

    Note to Section 140.0(c): The Commission periodically updates, publishes and makes available to interested persons and local enforcement agencies precise descriptions of the climate zones, which is available by zip code boundaries depicted in the Reference Joint Appendices along with a list of the communities in each zone.

    Note to Section 140.0: The requirements of Sections 140.1 through 140.10 apply to newly constructed buildings. Section 141.0 specifies which requirements of Sections 140.1 through 140.10 also apply to additions or alterations to existing buildings.

    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 140.1—PERFORMANCE APPROACH: ENERGY BUDGETS

    A building complies with the performance standards 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(c) and 10-116.

    (a) Energy budget. The energy budget is expressed in terms of long-term system cost (LSC) and source energy.

    1. 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, and lighting. 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 to the proposed design building.

    Exception to Section 140.1(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.

    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 140.2—PRESCRIPTIVE APPROACH

    To comply using the prescriptive approach a building shall be designed with and shall have constructed and installed systems and components meeting the applicable requirements of Sections 140.3 through 140.10.

  • § 170.1 Medium relevance — show source text

    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.

    1. 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.
    2. Field verification of individual dwelling unit systems. When performance of installed features, materials, components, manufactured devices or systems above the minimum specified in Section 170.2 is necessary for the building to comply with Section 170.1, or is necessary to achieve a more stringent local ordinance, field verification shall be performed in accordance with the applicable requirements in the following subsections, and the results of the verification(s) shall be documented on applicable Certificates of Installation pursuant to Section 10-103(a)3 and applicable Certificates of Verification pursuant to Section 10-103(a)5. A. EER2/SEER2/CEER/HSPF2 Rating. When performance compliance requires installation of a space-conditioning system with a rating that is greater than the minimum rating required by Table 170.2-K or specified for the standard

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    design, the installed system shall be field verified in accordance with the procedures specified in the applicable sections of Reference Residential Appendix RA3. B. Variable capacity heat pump (VCHP) compliance option. When performance compliance requires installation of a heat pump system that meets all the requirements of the VCHP compliance option specified in the ACM Reference Manual, the system shall be field verified in accordance with the procedures in Reference Residential Appendix RA3.4.4.3.

    C. Low leakage air handler. When performance compliance requires installation of a low leakage air-handling unit, the installed air handling unit shall be field verified in accordance with the procedures specified in Reference Residential Appendix RA3.1.4.3.9. D. Thermal balancing valve. When performance compliance requires installation of thermal balancing valves with variable speed circulation pump(s), the installation shall meet the procedures specified in Reference Residential Appendix RA4.4.3. E. Heat pump—rated heating capacity.

  • § 10-109 Medium relevance — show source text

    (b) 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(c) and 10-116.

    1. Energy budget. The energy budget is expressed in terms of source energy and long-term system cost (LSC). A. 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.

    i. The Efficiency LSC energy is the sum of the LSC energy for space-conditioning, water heating, mechanical ventilation, and the self-utilization credit.

    ii. The Total LSC energy is the sum of the Efficiency LSC energy and LSC energy from the photovoltaic system, battery energy storage systems (BESS), lighting, demand flexibility, and other plug loads. B. Source energy. The source energy budget is determined by applying the mandatory and prescriptive requirements of the standard design to the proposed design building. The source energy is the total annual source energy. Exception to Section 150.1(b)1. A community shared solar electric generation system, or other renewable electric generation system, or community shared BESS, which 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 and demand flexibility Energy Design Rating required to comply with the Standards, as calculated according to methods established by the Commission in the Residential ACM Reference Manual.

    1. Compliance demonstration requirements for performance standards. A. 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 which demonstrates, using an approved calculation method, that the building has been designed so that its energy consumption does not exceed the standard design energy budgets for the applicable climate zone. Exception to Section 150.1(b)2A Multiple orientation: A permit applicant may demonstrate compliance with the energy budget requirements of Section 150.1(a) and (b) for any orientation of the same building model if the documentation demonstrates that the building model with its proposed designs and features would comply in each of the four cardinal orientations.

    B. Field verification. When performance of installed features, materials, components, manufactured devices or systems above the minimum specified in Section 150.1(c) is necessary for the building to comply with Section 150.1(b), or is necessary to achieve a more stringent local ordinance, field verification shall be performed in accordance with the applicable requirements in the following subsections, and the results of the verification(s) shall be documented on applicable certificates of installation pursuant to Section 10-103(a)3 and applicable certificates of verification pursuant to Section 10-103(a)5. i. EER2/SEER2/CEER/HSPF2 Rating. When performance compliance requires installation of a space-conditioning system with a rating that is greater than the minimum rating required by Table 150.1-A or specified for the standard design, the installed system shall be field verified in accordance with the procedures specified in the applicable sections of Reference Residential Appendix RA3.4. ii. **Variable capacity heat pump (VCHP) compliance option.

  • § 150.1 Medium relevance — show source text

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    8 SINGLE-FAMILY RESIDENTIAL BUILDINGS—PERFORMANCE

    AND PRESCRIPTIVE COMPLIANCE APPROACHES

    SECTION 150.1—PERFORMANCE AND PRESCRIPTIVE COMPLIANCE APPROACHES FOR SINGLE-FAMILY RESIDENTIAL BUILDINGS

    (a) Basic requirements. Single-family residential buildings shall meet all of the following:

    1. The applicable requirements of Sections 110.0 through 110.10.
    2. The applicable requirements of Section 150.0 (mandatory features).
    3. Either the performance standards or the prescriptive standards set forth in this section for the climate zone in which the building is located. Climate zones are shown in Reference Joint Appendix JA2–Weather/Climate Data. Exception to Section 150.1(a)3: If a single contiguous subdivision or tract 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 150.0(a) through 150.0(r) apply to newly constructed buildings and Sections 150.2(a) and 150.2(b) specifies changes to the requirements of Sections 150.1(a) through 150.1(c) that apply to additions or alterations.

    (b) 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(c) and 10-116.

    1. Energy budget. The energy budget is expressed in terms of source energy and long-term system cost (LSC). A. 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.

    i. The Efficiency LSC energy is the sum of the LSC energy for space-conditioning, water heating, mechanical ventilation, and the self-utilization credit.

    ii. The Total LSC energy is the sum of the Efficiency LSC energy and LSC energy from the photovoltaic system, battery energy storage systems (BESS), lighting, demand flexibility, and other plug loads. B. Source energy. The source energy budget is determined by applying the mandatory and prescriptive requirements of the standard design to the proposed design building. The source energy is the total annual source energy. Exception to Section 150.1(b)1. A community shared solar electric generation system, or other renewable electric generation system, or community shared BESS, which 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 and demand flexibility Energy Design Rating required to comply with the Standards, as calculated according to methods established by the Commission in the Residential ACM Reference Manual.

  • § 170.1 Medium relevance — show source text

    170.1(a), 170.1(b), 170.2(c), Table 170.2-S, 180.2(b) Signs 120.6(h), 130.3(a)2, 140.6(a), 140.7(a), Table 140.7-B, 140.8(a), 141.0(b), 150.0(k), 150.1(b), 150.1(c), 160.5(d), 170.2(e), 180.2(b), 180.2(c) Temperature 110.2(a), 110.2(b), 110.2(c), 110.2(f), Table 110.2-F, Table 110.2-N, 110.2(f), 110.3(a), 110.3(a), 110.3(c), 110.8(d), 110.12(b), 120.2(a), 120.2(b), 120.2(c), 120.2(e), 120.2(i), 120.2(k), 120.3(a), 120.3(c), Table 120.3-A, 120.4(c), 120.5(a), 120.6(a), Table 120.6-B, Table 120.6-C, 120.6(b), Table 120.6-D, Table 120.6-E,

    Manufacturing, Commercial & Industrial Work Area Table 140.6-C Manufacturing, Commercial & Industrial Work Area-High Bay Table 140.6-C Manufacturing, Commercial & Industrial Work Area-Low Bay Table 140.6-C Museum Area 140.3(c), Table 140.6-C Museum Area-Exhibition/Display Table 140.6-C

    Museum Area-Restoration Room

    Table 140.6-C Office Area 130.1(c)5, 130.5(d), 140.4(a), 140.6(a), Table 140.6-C, 160.6(d), 170.2-E, Table 170.2-M, Parking Garage Area 130.1(c)7, 130.1(d), 140.6(a)3P, Q, R, 140.6(c)1, 140.6(d), 140.7(a), 140.7(c), 160.2(d), Table 140.6-C, Table 170.2-M Parking Garage Area-Daylight Adaptation Zone Table 140.6-C Parking Garage Area-Parking Zone and Ramps Table 140.6-C Pharmacy Area Table 140.6-C Religious Worship Area Table 140.6-C Restrooms 130.1(b), 130.1(c)5, 140.9(c)1, Table 140.6-C Retail Sales Area 120.2(e), 120.6(b), 140.4(a), 140.6(c)1, 140.6(d), Table 140.6-C Retail Sales Area-Fitting Room Table 140.6-C Retail Sales Area-Grocery Sales Table 140.6-C

    Retail Sales Area-Retail Merchandise

Frequently asked questions

How is the minimum BESS usable energy capacity calculated?

Minimum rated usable energy (kWh) is computed by the prescriptive equations (e.g., Equation 140.10‑B or 170.2‑E), which multiply the conditioned floor area subject to PV by a BESS capacity factor (Wh/ft²) and divide by the BESS round‑trip efficiency (with SARA adjustments where used); see Equations 140.10‑B/140.10‑C and Table 140.10‑B or the equivalent multifamily equations and tables .

How is the minimum BESS power (kW) requirement determined?

The code sets minimum power as a fixed relationship to the required energy capacity—expressed in the prescribed equations (for example Equation 140.10‑D and 170.2‑G), which establish the minimum rated power capacity as the energy capacity divided by 4 (the code’s prescriptive divisor) unless another code provision applies .

When does the code allow skipping a BESS?

The code includes exceptions: no BESS is required if the installed PV capacity is less than 15% of the PV capacity calculated by the PV equation, or if the computed minimum rated usable energy falls below the 10 kWh threshold; other occupancy‑specific exceptions (such as small tenant spaces or single‑tenant buildings under certain floor‑area thresholds) also apply — see § 140.10(b) and § 170.2(h) for the full list of exceptions and rules .

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