Ensure your curtains are thick enough to do the job. On sunny days, open the curtains on the south eastern side to take advantage of solar heat.
Do you have drafts around your entry doors? "Go Medieval," and hang a blanket or tapestry over the portal to block drafts.
Also, apply weather stripping to your doors and windows.
Had we not taken the House, I'd suggest heating rocks over a dung fire and bringing them into your home in iron buckets. Depending on whether the GOP knows how to behave with a modicum of power, we may still need to.
Ding, Ding, Ding .. Ding.
We have a WINNER! LOL