If you can install an AC, then it’s not hard to use them for heating as well. Heat pumps get better COPs when heating, than cooling. You would expect a COP of

If you can install an AC, then it’s not hard to use them for heating as well. Heat pumps get better COPs when heating, than cooling. You would expect a COP of 2 for cooling (I.e. 1000W of electricity removes 2000W heat), and a COP of 3 for heating (I.e. 1000W of electricity produces 3000W of useful heat). For heating a number of options exist from cheap electric heaters (which cost a lot to run); to gas or oil burners which require more infrastructure to build, but are cheap to run; and of course heat pumps, either air or ground sourced. For cooling, your only practical options are a heat pump, or an evaporative cooler if your in a dry climate. Both are more experienced up from than an electric heater, and require infrastructure. Finally insulating a home to retain heat naturally produced by those living inside can significantly reduce costs, along with insulating the humans (coats, jumpers etc). But cooling will always require a active component to move heat, and addition energy input. Although with good building design you can scavenge some of that energy using stuff like the stack effect.