This requirement is part of the endlessly confusing Rental Housing Safety Program. If you own a unit with a gas heating appliance (e.g., floor or wall furnace), then you must certify its good working condition every five years. Do this by obtaining an inspection from PG&E or a private mechanical contractor, and then submit the appropriate paperwork to the City of Berkeley Housing Department. Units built within the last five years are exempt. (See Rental Housing Safety Program webpage)