Chicago Heat Ordinance
From September 15 through June 1, the temperature inside a rental residence is required to be at least 68 degrees from 8:30 AM to 10:30 PM, and at least 66 degrees from 10:30 PM to 8:30 AM. Landlords face fines of up to $500 per day, per violation, for each day they do not supply adequate heat. The reason for lack of heat does not matter -- landlords must follow the law, and apartments must be heated.
If you are a renter and your landlord is not providing adequate heat, or no heat at all, you may file a complaint via CHI 311 website or mobile app or by calling 311. The Department of Buildings will inspect your unit and will take action against delinquent owners.