Cal. Health & Saf. Code § 17958.5
Except as provided in Section 17922.6, in adopting the ordinances or regulations pursuant to Section 17958, a city or county may make those changes or modifications in the requirements contained in the provisions published in the California Building Standards Code and the other regulations adopted pursuant to Section 17922, including, but not limited to, green building standards, as it determines, pursuant to the provisions of Section 17958.7, are reasonably necessary because of local climatic, geological, or topographical conditions.
For purposes of this section, a city and county may make reasonably necessary modifications to the requirements, adopted pursuant to Section 17922, including, but not limited to, green building standards, contained in the provisions of the code and regulations on the basis of local conditions.
Ca. Health and Saf. Code § 17958.5