Air source heat pumps have become much more efficient at lower temperatures than they used to be. The best units from Mitsubishi, Fujitsu, Gree, et al, put out

Air source heat pumps have become much more efficient at lower temperatures than they used to be. The best units from Mitsubishi, Fujitsu, Gree, et al, put out their nameplate rating down to -13 to -20F, and continue to produce >50% of their output at COP > 1 below -30F. For new construction, or if you need to replace your current boiler/furnace for some reason, heat pumps always beat gas in levelized cost unless gas is extremely cheap compared to electricity in your area. > unless you really like AC Given changes in climate as well as obesity rates, more and more people will really like AC as time goes on, even in the coldest places.