The rules concerning heat loss, illumination, and climate control standards adopted pursuant to section 326B.106, subdivision 1, shall include standards for all existing buildings heated by oil, coal, gas, or electric units which are owned by the state, the University of Minnesota, any city, any county, or any school district. Compliance with standards adopted pursuant to this section shall not be mandatory for buildings owned by any city, county, or school district, except as otherwise provided by this section.
The illumination standards promulgated pursuant to subdivision 1, are mandatory for all public buildings where economically feasible. For the purposes of this subdivision, "public building" means any building which is open to the public during normal business hours and which exceeds 5,000 square feet in gross floor area. The commissioner shall specify the formula for determining economic feasibility.
No enclosed structure or portion of an enclosed structure constructed after January 1, 1978, and used primarily as a commercial parking facility for three or more motor vehicles shall be heated. Incidental heating resulting from building exhaust air passing through a parking facility shall not be prohibited, provided that substantially all useful heat has previously been removed from the air.