I don't have any hard data at hand, but I can say that running my AC (which is just a one-way heat pump) for a few days out of the month in the summer makes my

I don't have any hard data at hand, but I can say that running my AC (which is just a one-way heat pump) for a few days out of the month in the summer makes my combined gas+electric bill about the same as in the middle of winter when my gas furnace is running all the time.