Forced air heating has many downsides.
We all know hot air rises. Because of this, builders heavily insulate the ceiling to prevent heat from escaping. In a two-story house, the upstairs becomes too hot, while the downstairs remains cool. We attempt to minimize discomfort by selecting one temperature that is tolerable throughout. But an open window or inadequate insulation sucks that heat right out of the house, wasting energy and increasing discomfort.