This depends entirely on the efficiency of the house to retain heat. In the extreme, if the house is 100% efficient then it needs to be heated just once in all

This depends entirely on the efficiency of the house to retain heat. In the extreme, if the house is 100% efficient then it needs to be heated just once in all eternity. Not to mention that in many locations it's quite possible to engineer a house (mostly lots of insulation) that can warm or cool itself to a large extent just by taking advantage of the local climate.