It doesn't really. The key is not letting the in house temp drop, as much as possible. My windows are old, so there is a constant draft. I have baseboard radiators for heat. It's probably 55 inside. currently around -20 without the wind outside. I personally think this whole thing is a bit overrated.
Wow 55! We did spray insulation a few years ago and I'm convincing myself it helped for my own sanity but truthfully I'm not too sure and they only did the attic since we didn't want to open walls. When it's really windy we have to stay in coats and blankets.
I think think the lowest I've seen my house get to was 64 and that's only because of the wind that keeps blowing in.
My gosh, I can't imagine being 55 inside, good luck and stay warm!