A fire in the fireplace is relaxing, but they don’t heat your home as thoroughly as you may think. Fireplaces deliver 10 percent or less of the fire’s heat to the room and will increase your heating bill in two ways. First, firewood costs more than the value of the delivered heat. Seasoned oak firewood must cost less than $20 per cord (a cord is a stack 4 feet wide by 4 feet high by 8 feet long) to provide heat from a fireplace at a cost comparable to a heat pump, according to the University of Tennessee Agricultural Extension Service. Fireplaces also require a large volume of air from the chimney. The incoming air cools the rest of the house, causing the primary heater to operate more than if you had no fire.