Monday, June 11, 2018


German windows—the Mercedes Benz of fenestration.
With the handle in one position, the sash tilts in;
in another, it opens like a casement. When closed,
it sealed flat-out airtight.
I never saw a serious window until I visited Germany during the 1980s. It was a revelation to find that German windows were built with the same Teutonic solidity as a Mercedes-Benz. They were massive, with broad, heavy frames of wood or polished aluminum joined with perfectly mitered corners. The lock hardware was both substantial and practical: with the handle in one position, the window tipped inward for ventilation; in another, it opened like a normal normal casement. Most importantly, when locked, the window was sealed virtually airtight against the elements. 

With Germany’s harsh climate and high energy costs, weathertight, energy-efficient windows have always been indispensable. Not so here in the States: as little as thirty years ago, the average tract house window still consisted of flimsy aluminum frames, with a single sheet of 3/16” glass, hit-or-miss gasketing, and rinkydink extruded hardware. These windows were affordable in first cost, but in terms of energy efficiency, they were little better than a hole in the wall. But back then, who cared? America got its energy dirt cheap. From Boise to Buffalo, the remedy for a cold, leaky house was simple—turn up the thermostat. 

By contrast, this is what most American homes had just
thirty years ago: Flimsy, leaky, aluminum dreck.
As energy prices began their inexorable climb, however, people suddenly realized how much of their heating dollar was literally going out the window. At least one progressive state government woke up to this fact as well. In 1978, California, then under the first two terms of Governor Jerry Brown, enacted Title 24, which mandated that new homes maintain a minimum level of energy efficiency. Despite the usual bellyaching over government intrusion into private business, it was the granddaddy of energy-efficiency legislation, and numerous states eventually followed suit. 

Only then did window manufacturers finally recognize the huge market for a window that was both affordable and energy-efficient. Nowadays, the best U.S.-made examples are just about on par with their German cousins, both in energy efficiency and construction quality. Some of the features to look for:

Triple glazing: Overkill for most U.S. climates, but
maybe not so for sound attenuation.
•  Double- and triple-glazing for improved R-values (a measure of an assembly’s resistance to the flow of heat—the higher the number, the less heat is conducted). Many states have made double-glazed windows all but mandatory, since they’re at least twice as efficient at retaining heat. Triple glazing performs even better, although the additional investment is seldom worthwhile in a mild climate. However, because the air captured between multiple panes of glass also serves to reduce noise transmission, you may want to consider using triple-glazed windows in rooms facing traffic noise or other unwanted sound. 

•  Inert gases sealed between the panes of double  and triple glazing. Gases such as argon conduct less heat than ordinary air, thereby improving the insulating value of the window assembly.

•  Vastly improved hardware and gasketing, which provide an airtight seal against infiltration of cold outdoor air, along with thermal breaks to prevent heat from being conduct ed outdoors via the window frame. Aluminum, in particular, is a notoriously efficient thermal conductor, so many window manufacturers now interpose less conductive materials such vinyl or rubber between inner and outer frames to help stem the flow of heat.

Today, American windows are almost on par with
European ones. Almost.
•  Low-e glass, which captures the sun’s warming infrared rays and prevents them from being re-radiated to the outdoors—a sort of one-way valve for heat—and UV-filtering glass that blocks ultraviolet radiation, which helps reduce fading of interior surfaces such as carpets, drapes, and furniture. 

Taken together, these improvements have saved countless millions of barrels of oil and kept who knows how much carbon out of the atmosphere. Granted, they took a generation to enter the mainstream of US building practices, but in the face of today's ever-more alarming changes in climate—well, better late than never.   

No comments:

Post a Comment