Don't forget about 20% transmission losses. I guess it'll depend on the climate, the COP of even the best heat pumps drops to 2 or worse in colder weather. I t

Don't forget about 20% transmission losses. I guess it'll depend on the climate, the COP of even the best heat pumps drops to 2 or worse in colder weather. I think I can agree that if it's a very mild climate and you frequently get a COP of 4 or better, then that could already beat a furnace in per-BTU gas consumption.