Cal. Civ. Code § 79

  § 79. Heating. 1. Every multiple dwelling exceeding two stories in
height and erected after April eighteenth, nineteen hundred twenty-nine,
and every garden-type maisonette dwelling project erected after April
eighteenth, nineteen hundred fifty-four, shall be provided with heat. On
and after November first, nineteen hundred fifty-nine, every multiple
dwelling shall be provided with heat or the equipment or facilities
therefor.  During the months between October first and May thirty-first,
such heat and the equipment or facilities shall be sufficient to
maintain the minimum temperatures required by local law, ordinance, rule
or regulation, in all portions of the dwelling used or occupied for
living purposes provided, however, that such minimum temperatures shall
be as follows:  (a) sixty-eight degrees Fahrenheit during the hours
between six o'clock in the morning and ten o'clock in the evening,
whenever the outdoor temperature falls below fifty-five degrees
Fahrenheit, notwithstanding the provisions of paragraph a of subdivision
four of section three of this chapter, and (b) at least fifty-five
degrees Fahrenheit during the hours between ten o'clock in the evening
and six o'clock in the morning, whenever the outdoor temperature falls
below forty degrees Fahrenheit. Nothing in this section shall be deemed
to relieve any owner of the duty of providing centrally supplied or
other approved source of heat prior to November first, nineteen hundred
fifty-nine in any case where such heat is required by this chapter or
any other law, ordinance, rule or regulation to be supplied in a
dwelling prior to said date. The heating system in dwellings used for
single room occupancy shall be in conformity with the requirements of
section two hundred forty-eight.
  2. The provisions of subdivision one shall not apply to any dwelling
(a) which is located in a resort community and is rented or occupied on
a seasonal basis between April fifteenth and October fourteenth during
any calendar year and is not occupied for living purposes during the
remainder of such year, except that occupancy of any such dwelling by
the family of a caretaker thereof or by the family of the owner thereof
during the remainder of the year shall be permitted; or (b) which the
department of city planning certifies is in an area to be acquired for a
public improvement or for development or redevelopment and for which (1)
a request for acquisition has been submitted to the mayor by a public
agency or (2) a plan for a development or redevelopment project has
received preliminary or first approval of the city planning commission;
or (c) for which a demolition permit has been or shall be issued by the
municipality pursuant to local law or ordinance.
  3. The exemption provided in subdivisions two (b) and two (c) of this
section shall be valid for a period of six months after the date of the
approval of the slum clearance or urban renewal plan or the date of such
certification or the date of the issuance of the demolition permit, as
the case may be, but such exemption may be extended from time to time by
the department provided, however, that such exemption shall not extend
beyond November first, nineteen hundred sixty-one.