What is the law on having utilities included in the rent and not having any control of what the temperature is

I recently moved into a duplex, the landlord lives downstairs and I live upstairs. All of the utilities are included in the rent. The issue is: The landlord controls the thermostat to the heat. I am freezing upstairs and she refuses to turn the thermostat up. Is there a law on what the temperature needs or must be when a landlord supplies the heat? I live in Lucas County in the State of Ohio. Thank you!