> "cooling a living space is always more costly than heating a living space" Man I wish this was true but it definitely isn't in anyplace that gets significantly cold. Heat pumps are super super efficient at cooling but they get less efficient at heating the colder it gets. Humans and appliances create a pretty negligible amount of heat.

I thought any place that is significantly cold can still dig underground and at some point you can get enough heat to run your heat pump?

Heating is more costly if you use technology created for cooling. When you try to cool a cold space in order to heat hot space, you will have a bad time. You could use electric heater for heating, it should have no problems with heating, but will use more electricity. Or you could use something actually cheaper, like wood or fossil fuels. If you use more expensive method (like electricity) it will be more expensive.