Furnace Room:

Although the University is made of stone and incredibly drafty (as all such large old buildings are mandated to be by University Edict no. 364/2b), it isn't actually freezing cold and no one has ever got frostbite. Additionally, there has always been plenty of hot water for the laundry, bath house and so on. There must be heat coming from somewhere but none of the students seem to know from where… but there are an awful lot of rooms in the basement that haven't been explored yet and are really rather warmer than you'd expect.