Tuesday, April 30, 2019


These are instantly recognizable as replacement windows—
the fake muntins between the double glazing is
a dead giveaway.
What kind of horrible person could find fault with a home improvement that saves energy?
You guessed it—me.

The improvement I’m talking about is window replacement. Some folks do it to reduce maintenance, others to update their home’s appearance. If your main motivation is to reduce your energy bills, however, there are many more cost-effective improvements you could make instead.

This house has lots of glass, but most don't—
the less glass, the less benefit you'll see from upgrading
your windows.
There’s no question that replacing single-glazed windows with new double-glazed ones will substantially cut heat loss through windows—typically by around 50%. What’s more, if your old windows are poorly weatherstripped, it’ll also reduce the infiltration of cold air. But that doesn't necessarily make new windows a good investment in energy savings.

Here's why: In the average house, windows constitute a relatively tiny fraction of the heated envelope—perhaps ten percent or so. This means that, while you may well be doubling the thermal efficiency of the windows, you are only realizing those savings on that ten percent sliver of the heated envelope, rather than on the whole envelope, as you would if you installed a new furnace. Hence, you’ll get far more bang for your buck by increasing attic and duct insulation, or better yet, replacing an obsolete furnace.

If your existing windows are really junk, you may
have a good reason to install high quality replacements
such as these.
On the other hand, if your windows have other problems--balky hardware, flimsy construction, or whatever--window replacement may be the right move. However, choose the replacements very carefully. If you have a prewar home with wood windows and you want to replace them with new color-coated aluminum or vinyl ones, make sure the replacements have the same hefty frame thickness and a similar finish.

 And unless your old windows are already white, avoid the tell-tale bright-white frames that are typically seen in replacement work.  Instead, choose a color that’ll complement your home’s existing color scheme

Whatever you do, make sure that the replacement windows
won't detract from the look of your house. Basically, prewar
houses have thick window frames, and postwar houses
have skinny ones
Postwar homes with aluminum windows pose a special problem. For some reason, people who wouldn’t dream of ripping the wood windows out of a Victorian think nothing of scrapping their postwar home’s aluminum windows and substituting clunky white vinyl ones with fake muntins. That’s a mistake. The slender, flat, and unashamedly metallic look of aluminum windows is an integral part of this look. If the original windows are natural or bronze-anodized aluminum, insist on the same finish. Don’t arbitrarily “upgrade” to some other window type because it happens to be in fashion at the moment.

In sum, two suggestions: Don't bother replacing your old windows for energy savings alone--you'll never recoup those savings. Put the money into more effective measures first. And if you do have good reasons replace the windows, make sure the new ones will complement your house, not detract from it.

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