“Windows are very frequently a source of lost heat in your home. Older homes may suffer from only having single-paned windows, which lose a large amount of heat, and even newer double-paned insulated windows lack enough insulation against cold winter temperatures and wind. However, you can save home heating costs and easily bulk up the insulation around your windows by making your own inexpensive thermal curtains.
Thermal curtains are energy-efficient window shades* that insulate against the cold around your windows. They are a thick and heavy buffer and can significantly decrease the money you spend on energy to heat your house. If you are handy with a sewing machine or know someone who is, there’s not much more you need than some old blankets or comforters, fabric, and a fair amount of time.”