I made "draperies" for my windows using quilted material. We've been using them for years & they really hold the heat in! The material is already quilted when you buy it, just have to edge it with binding. It comes in colors and patterns and works great.
I bet they do look nice. I’m no longer in a below freezing climate, albeit it did get down to 31 degrees last night. A bit early for that kind of weather down south. I like your idea, I could use them down here for a couple months to save money. Thanks.