I am in a high and dry climate. Really hot summers, and really cold winters, with this years cold snap lasting about a week or 2 longer than normal. I have double paned windows. And the greatest surface area are south and southwest facing. Our challenge is that we have only a wood stove for heat with a couple of ceiling fans to move the air around. I feel the home was designed poorly in this respect as the room with the wood stove has 30 foot ceiling. The windows are also set out from the house. If I used a curtain there would be a 3 foot gap between window and curtain. I plan on adding a rmh, but not for a while. I am starting small before I dig up my living room.