The main room of my townhome basement is 16' x 13' (210sq ft) and is joined to a wide stair hall (24' x 4') with my home office space at one end and a cold storage at the opposite (stair) end. The electric fireplace is 1500 watts and can heat the main room in about 10 mins. If the space gets too warm I can either crack the window in the main room or leave the cold room door slightly a jar. I am actually able to close off the two furnace heat registers in the space and use a combination of electric heat from the fireplace and heat-loss from the dimmable 20 halogen ceiling lights to warm the space.