ADU Compliance
ADU Title 24 requirements under the 2025 Energy Code
Short answer
New ADUs in California must comply with the Energy Code and are typically documented on a CF1R certificate of compliance. Under the 2025 code, heat-pump space and water heating form the residential baseline, and newly constructed detached ADUs may be subject to solar PV requirements, depending on the project.
Detached vs attached vs conversion
- Detached new ADU — modeled as a new dwelling.
- Attached ADU — often treated as an addition to the main home.
- Garage conversion — newly conditioned space; envelope upgrades usually needed.
Common sticking points
- Uninsulated slabs and walls in conversions
- Large glass areas facing west
- Gas water heaters against a heat-pump baseline
- Missing window U-factor/SHGC values on plans
Tip
Order the energy report before finalizing equipment and windows — the model can show the cheapest combination that complies.
Sources & official references
Related reading
This article is general information, not professional or legal advice. Always confirm requirements with your building department.
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