At 30° to 50° F my heat pumps are heating the top floor of 1200 sq feet for less than 10kwh per day. At $0.15 per kwh that is less than $1.50 a day for heat using the mini-split ductless. At those temps most of the time we heat with just the single 24K heat pump using two heads in living and dining rooms. The other 24k heat pump for bedrooms is used infrequently for heating.
Less than 30° we use propane boiler.
Less than 30° we use propane boiler.