California Code, Health and Safety Code - HSC § 53054

(a) A device, system, or design that utilizes solar energy or wind power for water heating, space heating or cooling, or the generation of electricity.

(b) Ceiling, attic, wall, or floor insulation.

(c) Storm windows and doors, multi-glazed windows and doors, and heat-absorbing or heat-reflective glazed windows and door materials, which substantially reduce the energy needed for space heating and cooling.

(d) Such other measures or devices as may reasonably be deemed energy conservation enhancements or structural improvements.