The Energy Efficiency Standards for Residential and Nonresidential Buildings were established in 1978 in response to a legislative mandate to reduce California's energy consumption. The standards are updated periodically to allow consideration and possible incorporation of new energy efficiency technologies and methods. New standards were adopted by the Commission in 2001 as mandated by Assembly Bill 970 to reduce California's electricity demand. The new standards went into effect on June 1, 2001.
California Energy Commission divided California into a 16 geographic area (zones) established a typical weather data, prescriptive packages and energy budgets, based on the location of the building a minimum wall, roof, floor insulation, U value and SCHG for windows required for all buildings envelope to comply with Title24 on prescriptive method.