Monthly special post number three, and the first for 2014… We’ve got a few inches of snow, and a nice layer of ice here, which is helping inform this month’s post.
Still, non-moving air has an R-factor (insulative value) of about 5 per inch. This means that in theory, if you could put a 10-inch layer of still air all around your house, you’d bump your R-factor up by about 50, more than sufficient for most reasonable locations in the U.S.
Unfortunately, the logistics of putting that sort of layer are quite complex. (We haven’t developed that sort of force-field yet, and I’d call it a long shot that we’re ever going to…) You’re pretty much stuck with what’s already in your walls. But wait–there’s a problem there, too: no matter how efficient and new they may be, your windows are (relatively speaking) big holes in your walls, as far as heat is concerned. What’s to be done?
We’ve got “heat curtains” in most of the rooms of our house: floor-to-ceiling drapery, in front of the windows. Generally speaking, several layers (at least two, in all cases–some of the windows have three). They give us about 3″ total of dead air space blocking each window they’re in front of–tacking an R-15 layer onto whatever the windows already are (ours are new, and fairly efficient–maybe R-5 or R-10? I’d have to dig up the brochure…). My wife, being who she is, made sure that the fabric colors go well with the rooms they’re in. The layer closes to the wall/window is generally a sheer of some sort; with the layers getting gradually thicker/more insulative as they go “inwards”.
There is special material available at fabric stores specifically for such uses; I’ve never seen it in anything other than white, though, so my recommendation would be to use it as a liner for the outer layer. As an added bonus, whatever you use, it will tend to block the light. This is great for those of you who are truly paranoid–it helps with “light discipline”; my favorite aspect of it, however, is that it makes the bedroom almost completely black at night–no disturbance from the headlights of passing vehicles, and on those rare mornings I get to sleep in, I’m thankful for the dark.
I’ve seen others use quilts for the same purpose, with special hangers for them at the windows. Whichever way you go, you’ll have given your home a nice energy-saving bost.