Help us figure out how to insulate our condo windows!

December 31, 2008 4:27 PM

Window treatments that insulate. Really big windows in a really old building. How?

[this is long, sorry]
We live in a renovated historic building that was originally built in the late 1800's. In 1994, the space was converted to residential condos. Our windows are huge. Like, 10' tall and about 6.5' wide. (The width is segmented into 3 equal-ish bays of about 2' each.) We have 3 of these ginormous windows. Glass is double pane, but these things are cheap.

The slackass developer cheaped out on a number of things, the window treatments among them. So despite having lived here for 11 years, we still have the original aluminum mini blinds on all three window segments of each window. the blinds act as a radiator (?), dissipating heat like nobody's business. Further, the vertical mullions are also aluminum, and part of the giant heat sink known as our living room exterior wall.

I went over to the local shop with measurements in hand & came away equally immobilized. I wanted to go with honeycomb shades, but the height stretches out the pleats too much from the weight of the shade itself. Unless we go with the super expensive honeycombs with structural support.

We also considered plantation type blinds with wider slats made of plastic, since the guy said the R factor would be in the middle between the mini blinds (nil) and the honeycombs (I forget the number). This one is still in the running, but it doesn't solve the vertical mullion heat loss problem.

The sills are deep - the cats love sitting on them and watching the birds. But we are freezing and need to figure out a decent modern looking solution. It's not likely the HOA will be replacing the windows for more efficient ones anytime soon. Recaulking is done once a year to the whole building.

So short of doing something for the upper 3rd of the windows and something else for the lower 3rd (to try to open up the options around the weight problem), what are our options? Money is a secondary issue to keeping our heat.

signed,
mme. freezyfeet

posted by yoga to home & garden (7 comments total)

uh, make that "lower 2/3rds..." Also, we crack the window open less than an inch occasionally just for some fresh air, even in winter. We face east.

Thanks for your patience. :)
posted by yoga at 4:29 PM on December 31, 2008

Some curtains come with a "thermal suede" (or "thermalsuede"?) lining that is supposed to provide added insulation value, which would be another option in addition to the honeycomb shades.
posted by washburn at 5:17 PM on December 31, 2008

I was just looking at pretty, oatmeal-colored thin canvas drop cloths (for painting) at Home Depot this week and some of them come lined with clear plastic on the reverse. Thought they might solve a similar problem for our big front glass window -- of course, our living room is rather oatmeal-colored, your mileage may vary, but I think slipping a rod through the hemmed edge and hanging them up might just work!
posted by bitter-girl.com at 6:33 PM on December 31, 2008

Take a look at these Warm Windows. They saved us 40% of our fuel bill the winter after we made them. The Warm Window fabric is available by the yard at Joanne Fabrics as well as other fabric stores, along with instructions. There are a number of businesses custom building them, as well.
posted by northernlightgardener at 6:34 PM on December 31, 2008

My house is about the same deal, only ours have single-pane glass. My wife's solution was to sew curtains with insulating fabric. (Actually, a sandwich of fabrics—insulating fabric is pretty ugly. :) The result is that our house stays much, much warmer. The condensation will freeze on the window, while the air a few inches away (on the other side of the curtains) might be 65°. Recommended.
posted by waldo at 7:13 PM on December 31, 2008

Oh, hey, I basically repeated what northernlightgardener said. Sorry. :)
posted by waldo at 7:14 PM on December 31, 2008

the blinds act as a radiator (?), dissipating heat like nobody's business.

I doubt this is the case. If anything, the blinds actually give you a (very low) insulation value. Nil is about right. But they won't radiate your heat away, and if closed at night, will reduce air circulation by the windows, while allowing solar heat in if open during the day.

Different blinds are not really the answer. Either heavy curtains or those "warm window" things will begin to make a real difference.

You need to add another layer of insulation. Amazingly effective, plastic shrink-film window treatments are inexpensive and give you a ginormous ROI bang-for-your-buck, simply because they create a more or less sealed compartment of insulating air. Believe me, they don't look like they'll work, but they will. (I live in a 1920s apartment that has ... window issues. I could feel the difference immediately.) Best of all, they come off in a jiffy when it warms up.

Note that while the shrink film may stop or slow drafts, its real purpose is to halt the air circulation that cools your room air against the glass. If you can caulk or weatherstrip any leaks before closing up the film, so much the better -- the insulating air buffer won't get as cold.
posted by dhartung at 12:06 AM on January 1 [1 favorite]