 This is because the compressor's input energy is also converted to useful heat when in heating mode, and is discharged along with the transported heat via the condenser to the interior space.But for cooling, the condenser is normally outdoors, and the compressor's dissipated work (waste heat) must also be transported to outdoors using more input energy, rather than being put to a useful purpose.For the same reason, opening a food refrigerator or freezer has the net effect of heating up the room rather than cooling it, because its refrigeration cycle rejects heat to the indoor air.