I have a large garage/barn with a 2nd floor loft office. The building is 24x48 with 12 ft walls and all open ceilings except for the 14x16ft office. We heated the whole building with a kerosene Monitor heating unit. One 275 gal tank full of kerosene lasted all winter (We are in Maine). We left in on with the thermostat set at 65 and with the heat rising into the office it was even warmer there.