Do ADUs Require a Title 24 Energy Report in California?

Short answer: yes, every Accessory Dwelling Unit in California requires a Title 24 Energy Compliance Report as part of the building permit process. This applies regardless of the ADU's size, whether it's detached, attached, or a garage conversion, and regardless of which city or county is issuing the permit.

This surprises some homeowners, particularly those converting an existing garage where no new building envelope is being constructed from scratch. But under Title 24, a garage conversion is treated as a change of occupancy — the space goes from unconditioned storage to conditioned living space — which triggers full energy compliance review, including insulation, window, and HVAC requirements appropriate to your climate zone.

For detached new-construction ADUs, the report needs to address the complete building: foundation, walls, roof, windows, HVAC system, water heating, and (depending on size) potentially lighting controls and ventilation requirements. Detached ADUs are generally evaluated similarly to small single-family homes from an energy modeling perspective.

Attached ADUs — those sharing a wall or roofline with the primary residence — sometimes have a marginally simpler compliance path since some building systems may be shared, but they still require their own dedicated CF1R documentation.

Junior ADUs (JADUs), capped at 500 square feet and required to be within the existing footprint of the primary residence, are not exempt either. JADU projects typically use a CF1R-ADD or CF1R-ALT form depending on scope, but the energy compliance requirement is the same in substance.

One planning note: HERS (Home Energy Rating System) verification requirements vary by which compliance credits your ADU's energy model relies on. Certain prescriptive shortcuts — like specific duct sealing or air leakage credits — trigger mandatory field verification during construction. A well-prepared Title 24 report will flag this clearly upfront, so your contractor knows to schedule a HERS rater before final inspection rather than discovering the requirement late in the process.

Given how universal this requirement is, the practical question for most ADU builders isn't whether they need a report, but how to get an accurate one quickly enough to keep their permit timeline on track.