money out the window

R-Value and Drape Insulation

In the last week I have had several requests to add lining to existing drapes. For those of you who have been thinking about it but need a bit more information, here is a brief summary of the infomercial I presented at the Shuswap Women in Business meeting last month.

Hunter Douglas, one of the largest manufacturers of window coverings suggests that up to 25% of our annual heating bills go out the windows. They have produced a variation on the honeycomb shade, the Architella with an R value of 7.7. So what is R-Value anyway? R is a measure of resistance to heat transfer. R-Value is not the best way to measure a window’s heat loss protection value but it is the most common. (U value is the insulation rating for transparent objects.)

A home with 4” studs must have R-12 insulation. If you have a double insulating glass window with 1/2” air space between the layers, the R value of the window is about 2. Add a single layer of fabric, almost no increase, add a plain lining for an increase of about 1 for a total R value of R3. Add a black out lining; R-value is up to about R5 or 6. Add an interlining, and the R value jumps to about R9. Add an insulated Roman Blind and valance and the R value of the whole window treatment becomes about R16. Remember that the window treatments you are using to reduce heat loss must be snug to the window and layers will provide the best protection. If you have a blind inset into your window frame and the gap on each side is 1/8”, over 80 inches (40 inches on each side) this equates to a 3” x 3” hole in your coverage.

As a full service drapery workroom, I will add lining to existing drapes, either a permanent or removable liner, or you can find pre-made panels at Zellers or Fabricland or through many on-line home decor stores. If they are blackout liners, you will get the most protection against heat going out the window in the winter and heat coming in during the summer. If they are too long they can be hemmed.

Thanks to all of you who came out to watch me work on the wing chair at Fabricland. The chair cover is done, stop in and see it or have a look at it on and connect to the Gallery via the flashing book icon.

Have a read of my post of December 8, 2008; ‘How much does it cost to heat one window?’ Lots more info there.

If you’d like to know how much YOU are spending to heat your windows, e-mail me at

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