(A) General. Dwellings shall be provided with heating facilities capable of maintaining a room temperature of 68°F (20°C) in all habitable rooms, bathrooms and toilet rooms based on the winter outdoor design temperature required for the locality indicated in Appendix D of the Illinois Plumbing Code. Cooking appliances shall not be used to provide space heating to meet the requirements of §§ 151.545 through 151.549.
(B) Exception. In areas where the average monthly temperature is above 30°F (-1°C), a minimum temperature of 65°F (18°C) shall be maintained.
(2009 Code, § 29-6-5)