> if the heat pump is designed to operate in very cold weather the minimum efficiency is 100% (backup resistance heating), so you will always at least break ev

> if the heat pump is designed to operate in very cold weather the minimum efficiency is 100% (backup resistance heating), so you will always at least break even versus pure resistance heating. But the heat pump has a "outside" part, where there is a fan and other electrify using stuff. Can you not risk that more heat is generated outside than is moved inside?