Accessory dwelling units are modeled as their own building for Title 24 purposes — different rules than remodeling the main house. We calculate it against the classification that actually applies.
Detached ADUs are treated as standalone dwelling units for Title 24 compliance — their own envelope, their own systems, their own CF1R. Attached ADUs and garage conversions bring a different wrinkle: the shared wall or existing structure changes which compliance path applies. Junior ADUs (JADUs), which reuse space within the existing home, often follow existing-building rules rather than new-construction rules. Getting the classification right at the start avoids a rejected report later.
Modeled as an independent new building — full envelope, HVAC and water heating compliance calculated from the ground up.
Compliance calculated for the added conditioned area, accounting for the shared wall or roof with the existing structure.
Scoped against existing-building compliance paths where applicable, rather than treated as new construction.
Yes, in almost all cases. New ADUs — detached, attached or converted — are subject to Title 24 Part 6 energy compliance as part of the building permit process.
Yes. Conditioned floor area, window-to-wall ratio and the specific HVAC/water heating equipment all factor into the model, so a 500 sq ft studio ADU and a 1,200 sq ft two-bedroom ADU will have different compliance requirements even on the same lot.
Yes — we typically run the calculation alongside drafting so the drawings and the energy report stay consistent with each other by the time of submittal.
If a prescriptive compliance path doesn't pencil out, we can run a performance-based calculation instead, which allows trade-offs between different building components (for example, better windows offsetting less wall insulation) to still meet the overall standard.
Tell us what you're building and we'll get back to you with next steps — usually within one business day.
(408) 634-6655
Yuna Drafting