California climate zones 1–16
The California Energy Commission divides the state into 16 building climate zones. Your zone shapes every Title 24 calculation.
Why climate zones matter for Title 24
The California Energy Commission groups locations with similar weather into 16 building climate zones. Every Title 24 energy calculation uses the zone of the project’s physical address. The zone decides which prescriptive values apply (insulation levels, window U-factor and SHGC, and equipment efficiency), and it weights heating against cooling in performance modeling.
That is why the same ADU design can comply easily in coastal Zone 6 but need upgrades in desert Zone 15 or mountain Zone 16. Pick a zone below for its climate character, typical project considerations and example communities.
Representative cities from the CEC “California Building Climate Zones” dataset. Load-profile labels are simplified educational groupings, not CEC classifications.
Ready to get your Title 24 report?
Upload your plans in minutes. We’ll handle the modeling, the forms and the plan-check revisions.