Not OP, but my assumption is that better insulation means you need less heating and cooling. I've lived in a home with a literal hole to the outside. During t

Not OP, but my assumption is that better insulation means you need less heating and cooling. I've lived in a home with a literal hole to the outside. During the winter we had to run the radiators non-stop and it was still freezing. If you are trying to save energy, then sealing up and improving insulation will generally have the largest bang for the buck.