years ago I made a few window quilts for some North facing windows. I used a product called "thin-su-late" I think that is how it is spelled. It was silver type material-no batting attached. I know you can now buy it with the batting already attached. Anyway, made my quilts the traditional way and added a layer of thinsulate. Used sticky Velcro to attach them to window frame. In the day time I just un Velcro-ed to let the sun in or left them up on dreary days. Make your quilts large enough to cover the frames of windows. What you are trying to achieve here is an air block that traps the cold air from the window between window and quilt. Works great.. Also good for drafty doors that don't get much use.. one of mine was the landscape that I would have seen out that window in the fall... (or you could do a happy SUMMER scene! ) Happy Quilting and STAY WARM....