Title 24 California Climate Zones 1-16
Energy use depends partly on climate conditions which differ throughout the state. To standardize Title 24 calculations and to provide a basis for presenting the criteria, the California Energy Commission has established 16 climate zones which are used with both the low-rise residential and the non-residential Title 24 energy standards. Cities may occasionally straddle two climate zones. In such cases, the exact building location and correct climate zone should be verified before any energy calculations are performed. If a single building development is split by a climate zone boundary line, it must be designed to the requirements of the climate zone in which 50% or more of the dwelling units are contained.
(Excerpted from the CEC Title 24 Residential Compliance Manual)