 While the gas utilization efficiency in such a device, which is the ratio of the energy supplied to the energy consumed, may average only 1.5, that is better than a natural gas or LP gas furnace, which can only approach 1.By definition, all heat sources for a heat pump must be colder in temperature than the space to be heated.Most commonly, heat pumps draw heat from the air (outside or inside air) or from the ground (groundwater or soil).