(a) A dwelling shall be deemed untenantable for purposes of Section 1941 if it substantially lacks any of the following affirmative standard characteristics or is a residential unit described in Section 17920.3 or 17920.10 of the Health and Safety Code:

(1) Effective waterproofing and weather protection of roof and exterior walls, including unbroken windows and doors.

(2) Plumbing or gas facilities that conformed to applicable law in effect at the time of installation, maintained in good working order.

(3) A water supply approved under applicable law that is under the control of the tenant, capable of producing hot and cold running water, or a system that is under the control of the landlord, that produces hot and cold running water, furnished to appropriate fixtures, and connected to a sewage disposal system approved under applicable law.

(4) Heating facilities that conformed with applicable law at the time of installation, maintained in good working order.

(5) Electrical lighting, with wiring and electrical equipment that conformed with applicable law at the time of installation, maintained in good working order.

(6) Building, grounds, and appurtenances at the time of the commencement of the lease or rental agreement, and all areas under control of the landlord, kept in every part clean, sanitary, and free from all accumulations of debris, filth, rubbish, garbage, rodents, and vermin.

(7) An adequate number of appropriate receptacles for garbage and rubbish, in clean condition and good repair at the time of the commencement of the lease or rental agreement, with the landlord providing appropriate serviceable receptacles thereafter and being responsible for the clean condition and good repair of the receptacles under his or her control.

(8) Floors, stairways, and railings maintained in good repair.

(9) A locking mail receptacle for each residential unit in a residential hotel, as required by Section 17958.3 of the Health and Safety Code. This subdivision shall become operative on July 1, 2008.

(b) Nothing in this section shall be interpreted to prohibit a tenant or owner of rental properties from qualifying for a utility energy savings assistance program, or any other program assistance, for heating or hot water system repairs or replacement, or a combination of heating and hot water system repairs or replacements, that would achieve energy savings.