We all love our windows, but come winter time, they cause us to lose our heat. This happens due to the fact that no matter what kind of windows you have, they simply are not made to keep out the cold. There is an easy solution to this, curtains. With most curtains, however, there is a gap between the wall and the curtain. This creates a small wind cycle in which the warm air rises and the cool air from the windows pulls the warm air down the window, causing it to become a cold draft out the bottom of the window. One way to fix this is to put a pelmet over the top that stops the warm air from going down the window.
Read the full article here House Insulation: Winter Curtains -DIY Advice Blog-Family Handyman DIY Community