Is my landlord responsible for my heating bills?

I live in MN in a drafty house with poor heat circulation. Some parts of the house are 75–80 degrees while others are freezing, literally. Our pipes keep freezing even though our thermostat is always set above 70. When the pipes freeze, the landlord is always very responsive and hes here working on it within an hour. But in order to heat the pipes, he uses several 1500w heaters, turns the furnace up to 80, and leaves doors open and turns fans on to circulate the heat. Is my landlord at least partially responsible for my utility bills or is this my problem?