Layers are the Key.
Last column was about how much heat goes out your windows. This one is about what you can do to reduce that loss without getting new windows or a second mortgage.
The key here is to prevent the cold air outside the window from meeting the warm air of the room through the use of layers. If you add layers between the window and the room, you can make a huge dent in the heat loss. Cold air will sneak in around the window covering — on the sides and above and below, so add your heat-loss prevention solutions to the largest area possible. If you are adding curtains, for example, extend them past the window frame in all directions as much as you can.
That old standby plastic on the window frames can double the R-value of the window. It works about as well as adding a one-layer curtain — if it is applied correctly. Buy the kit and follow the directions. These aren’t the same as the kits of even a few years ago; they work much better now.
Add a second layer behind
If you have a blind on the window, consider adding a blackout Roman Blind behind the existing one. You may have to move your blinds forward a bit. Have one made of flannel and blackout lining, it will give you added R-value of about 3 or 4 . From some like me, that should cost you about $15.00 per square foot. If that is outside your budget, buy a roller shade or ready-made roman, the R-value will be lower, but anything is better than nothing. It’s best if you can get a “reverse roll”; the shade rolls off the roller toward the window, not down the front.
Add a similarly constructed Roman Blind in front of the existing blinds. Plan on removing it in the summer.
One more- drapery layer
Add lined drapes over your window blinds or shades.
Add blackout removable liners to existing drapes. There are ready-made ones available everywhere. They attach to either the drape or the curtain rod. For added insulation, buy some thin cotton quilt batting and attach it to the backside of your drapes. (Safety pins work just fine, no one will see them.)
The difference layers make:
Here is a snapshot: Window: R-value 2. Add a double cellular shade, R-Value is up to 6 or 7. Add flannel-lined blackout drapes, you are up to about an R-value of 14 or so. Add a valance at the top and the R-value of the whole shebang is up to 16 or more.
This is a good article. Check it out.