Title 24: California Energy Standards

Building Energy Efficiency Standards for California

Last updated: April 10, 2026

What is in effect right now

The 2025 Building Energy Efficiency Standards (Title 24, Part 6) took effect on January 1, 2026. Any project whose permit application is submitted on or after that date must comply with the 2025 cycle. Projects permitted before January 1, 2026 follow the 2022 cycle.

Three things changed most in the 2025 cycle compared to 2022: heat pump space and water heating are now favored through the energy budget calculation in single-family and low-rise multifamily construction; new electric-ready provisions require pre-wiring and pre-plumbing for heat pump water heaters and electric cooking in multifamily buildings and commercial kitchens; and prescriptive envelope and ventilation requirements have been tightened across most climate zones.

Overview

Title 24 is the California Building Standards Code, the body of regulations that governs how buildings are designed and constructed in the state. Within Title 24, Part 6 is the Building Energy Efficiency Standards, which set the energy performance rules for new construction, additions, and alterations. The standards are updated on a roughly three-year cycle by the California Energy Commission, then adopted by the California Building Standards Commission as part of the triennial code edition.

The standards cover building envelope, mechanical systems, water heating, lighting, and on-site energy generation. They apply to single-family homes, low and high-rise multifamily buildings, and nonresidential buildings. Cool roof requirements, insulation R-values, fenestration U-factors, and HVAC efficiency minimums all live inside Part 6 and vary by climate zone. California has 16 climate zones, and the prescriptive requirements for each one are different.

Compliance is verified during plan check by the local building department, and many measures also require field verification by a HERS rater after construction. Local jurisdictions can adopt amendments that go beyond the state minimums, called reach codes, so requirements in places like Berkeley, San Francisco, and Palo Alto can be stricter than the statewide baseline.

The 2025 Cycle in Detail

The 2025 Building Energy Efficiency Standards were adopted by the California Energy Commission in September 2024 and approved by the Building Standards Commission as part of the 2025 Triennial Edition of Title 24, published July 1, 2025. The new requirements apply to permit applications submitted on or after January 1, 2026. The 2022 cycle continues to apply to projects permitted before that date.

Heat pump heating and water heating

The 2025 cycle uses energy budgets that effectively favor heat pumps for space conditioning and water heating in newly constructed single-family and low-rise multifamily buildings. Designers can still use gas equipment, but the building has to compensate elsewhere to hit the budget. New mandatory provisions also apply to heat pump water heater installations, including ventilation and pipe insulation requirements.

Electric-ready requirements

Multifamily buildings and commercial kitchens that install gas water heating or gas cooking now have to be wired and plumbed so an electric replacement can be swapped in later without major retrofit work. The intent is to lower the cost of future electrification without forcing it during initial construction.

Tightened envelope and ventilation

Wall insulation, slab edge insulation, and window performance got incremental upgrades in the prescriptive packages. Cool roof prescriptive aged solar reflectance values were updated for several climate zones. Ventilation requirements were strengthened to improve indoor air quality, particularly for multifamily projects.

Component Guides

Two of the most frequently asked-about pieces of Title 24 Part 6 are the cool roof prescriptive requirements and the insulation R-value minimums. Both vary significantly by climate zone.

Cool Roof Requirements

Solar reflectance, thermal emittance, and climate zone requirements for compliant roofing

Insulation Requirements

Minimum R-values for walls, roofs, floors, and ducts by climate zone

Key Requirements

Cool roofs with minimum aged solar reflectance and thermal emittance, varying by climate zone and slope
Climate zone-specific prescriptive R-values for walls, ceilings, floors, and ducts
CRRC-rated roofing products for compliance verification
Heat pump water heater ventilation and pipe insulation provisions in new construction
Electric-ready wiring and plumbing rough-ins in multifamily and commercial kitchen projects
HERS field verification for measures including duct leakage, refrigerant charge, and quality insulation installation
Mandatory ventilation rates for indoor air quality, with strengthened requirements in the 2025 cycle

Prescriptive vs Performance Compliance

Title 24 Part 6 gives designers two ways to demonstrate compliance. The prescriptive path is a checklist. Each component, the wall insulation, the window U-factor, the duct R-value, the cool roof reflectance, has to meet or exceed a minimum value spelled out in tables for each climate zone. There is no flexibility to trade one requirement against another.

The performance path uses approved energy modeling software to demonstrate that the proposed building uses no more energy than a reference building built to the prescriptive standard. This path lets designers undershoot one requirement if they overshoot another. A high-performance window package, for example, can offset thinner wall insulation. Most large or unusual projects use the performance path because it is more flexible.

Tip: Software approved by the California Energy Commission for performance compliance includes CBECC-Res for residential and CBECC for nonresidential. The output is a CF1R form that gets submitted with the permit application.

Frequently Asked Questions

Which Title 24 cycle applies to my project?

The cycle in effect on the day your permit application is submitted is the cycle that governs the project. Permit applications submitted on or after January 1, 2026 fall under the 2025 cycle. Applications submitted before that date stay on the 2022 cycle, even if construction does not begin until later.

Does Title 24 apply to remodels and additions?

Yes. Additions, alterations, and repairs are all subject to Part 6, but the requirements are scaled to the scope of work. Replacing a few windows triggers the prescriptive U-factor and SHGC requirements for those windows. A re-roof in a climate zone with cool roof requirements triggers the prescriptive solar reflectance values. A whole-house remodel can trigger duct sealing, HERS verification, and insulation upgrades depending on what is being touched.

What is the difference between prescriptive and performance compliance?

Prescriptive compliance is a checklist where every component has to meet a minimum value from a table. Performance compliance uses energy modeling software to show the whole building uses no more energy than a reference building built to the prescriptive standard, which lets designers trade off one component against another. Most architecturally complex or high-performance projects use the performance path because the prescriptive tables are too rigid for them.

Who enforces Title 24?

Local building departments enforce Title 24 during plan check and field inspection, the same way they enforce the structural and life-safety codes. The California Energy Commission writes and updates the standards, but it does not directly inspect projects. For measures that require HERS field verification, an independent certified HERS rater performs the verification and registers the results.

What is a HERS rater and when do I need one?

A HERS rater is a certified third party who performs field verification of specific Title 24 measures, including duct leakage testing, refrigerant charge verification, fan watt draw, quality insulation installation, and whole-building airtightness for projects pursuing tighter envelope compliance credit. The contractor or builder typically arranges the HERS rater. Results are filed in the HERS registry and reviewed by the building department before final.

Does the 2025 cycle ban gas appliances?

No. The 2025 standards do not prohibit gas furnaces, gas water heaters, or gas cooking statewide. The change is that the energy budget calculation treats heat pumps as the baseline assumption, so gas equipment makes the project work harder elsewhere to comply. Some local reach codes do effectively require all-electric construction, but that is a city or county decision, not a state requirement.

How do climate zones affect the requirements?

California has 16 climate zones, and prescriptive requirements vary by zone because heating and cooling loads are different across the state. Cool roof reflectance minimums, wall and ceiling R-values, duct R-values, and window U-factors all change from zone to zone. A project in coastal Climate Zone 3 has different prescriptive numbers than one in inland Climate Zone 14. The Energy Commission publishes a climate zone map and a ZIP code lookup that identifies the zone for a given project address.

Where can I find the official compliance manuals?

The California Energy Commission publishes residential and nonresidential compliance manuals, prescriptive packages, and forms on the Building Energy Efficiency Standards page on energy.ca.gov. Energy Code Ace, a CEC-funded program, also publishes plain-language fact sheets, training, and reference tools that many designers find easier to navigate than the compliance manuals themselves.