Residential buildings. Every dwelling shall be provided
with heating facilities capable of maintaining a room temperature
of 65° F. (18° C.) At a level of three feet above the floor
and a distance of three feet from the exterior walls, in all habitable
rooms, bathrooms, and toilet rooms based on the outside design temperature
required for the locality by the mechanical code. Every owner and
operator of any building who rents, leases, or lets one or more dwelling
unit, rooming unit, dormitory unit or guest room on terms, either
express or implied, to furnish heat to the occupants thereof shall
supply sufficient heat during the period from October 1 to May 1 to
maintain a room temperature of not less than 65° F. (18° C.)
in all habitable rooms, bathrooms and toilet rooms during the hours
between 6:30 a.m. and 10:30 p.m. of each day and not less than 60°
F. (16° C.) during other hours. The temperature shall be measured
at a point three feet above the floor and three feet from the exterior
walls. When the outdoor temperature is below the outdoor design temperature
required for the locality by the mechanical code, the owner or operator
shall not be required to maintain the minimum room temperatures, provided
the heating system is operating at full capacity, with supply valves
and dampers in a full open position.