What changed with the 2025 California Title 24 energy code for ADUs?

California revises its Building Energy Efficiency Standards on a three-year cycle, and the 2025 code took effect for permit applications submitted on or after January 1, 2026. For ADUs, the broad direction continues the state's push toward all-electric, high-efficiency building — heat pumps and heat-pump water heaters as baselines — with refinements to envelope, ventilation, and electrification-readiness provisions. Which cycle applies to your project depends on when you submit.

The two cycles ADU owners deal with today

The submittal date generally determines the cycle, so a project permitted in late 2025 typically follows the 2022 code, while one submitted in 2026 follows the 2025 code. Confirm the cutoff handling with your jurisdiction, since some have intake-timing nuances.

What the 2025 direction emphasizes for ADUs

Rather than inventing specific numbers, here is the practical thrust of the current code direction for new ADUs:

• Heat-pump baselines. Heat pumps remain the prescriptive baseline for space conditioning, and heat-pump water heaters remain the baseline for water heating in most new dwelling units.
• Electrification readiness. Continued emphasis on solar-ready and battery/energy-storage-ready (ESS-ready) provisions for many new units.
• Envelope and ventilation. Ongoing refinement of insulation, window performance, and whole-dwelling ventilation (ASHRAE 62.2) requirements.
• Lighting. High-efficacy LED sources and required controls remain standard.

Because exact thresholds, credits, and exceptions differ between the 2022 and 2025 cycles, the safest approach is to design to the cycle that will be in force when you submit — not the one in force when you start planning.

What to do about it

1. Estimate your likely permit-submittal date — this points to the applicable code cycle.
2. Confirm the project address so the correct climate zone is applied for that cycle.
3. Have the CF1R prepared to the in-force cycle, with equipment and provisions matched on the MEP sheets.

The applicable code cycle and local amendments vary — confirm with your local building department; many cities also adopt all-electric reach codes that go beyond the statewide minimum. We set the registered CF1R to the cycle that applies to your submittal and coordinate it with your plans as a +$240 Title 24 add-on; see Title 24 Reports or the ADU Title 24 guide.