In Massachusetts, the State Sanitary Code (105 CMR 410) provides minimum standards of safety, cleanliness, and comfort for an apartment to be considered legally fit for human occupation.
The State Sanitary Code establishes the temperature that an apartment must be maintained during the “heating season” (September 15 – June 15):
410.201: Temperature Requirements
The owner shall provide heat in every habitable room and every room containing a toilet, shower, or bathtub to at least 68°F (20° C) between 7:00 A.M. and 11:00 P.M. and at least 64°F (17° C) between 11:01 P.M. and 6:59 A.M. every day other than during the period from June 15th to September 15th, both inclusive, in each year except and to the extent the occupant is required to provide the fuel under a written letting agreement. The temperature shall at no time exceed 78°F (25° C) during the heating season…