Heat Pump vs Furnace Efficiency
Heat pumps move heat rather than generating it, achieving COPs of 2-4 (200-400% efficient). The HSPF (Heating Seasonal Performance Factor) rates heating efficiency; divide by 3.412 to get average COP. A gas furnace with 96% AFUE has an effective COP of 0.96. Even at higher electricity rates, heat pumps often win when gas costs exceed $1/therm and electricity is under $0.15/kWh.