It seems like a very long time ago, doesn’t it, that windows were considered simple building components? As long as they opened and closed and let in sunlight most of us were content. We know now that windows are anything but simple. They’re an essential part of an energy efficient building envelope; they must simultaneously admit sunlight (and a certain amount of solar energy — but not too much), minimize heat loss or gain, prevent drafts, and last a generation or two.
This week’s Q&A Spotlight from Green Building Advisor starts with a simple question from someone looking for just such a window. Claire Anderson wondered about the experiences that GBA readers have had with windows from Serious Windows, Thermotech Fiberglass, Fibertec, Inline and Accurate Dorwin. “I’m having a difficult time,” she wrote, “finding high SHGC windows (with a U-value less than or equal to 0.30) for my passive solar home that are affordable.”
As simple as it sounds, the question proved complex: Who makes a window with a high solar heat gain coefficient (SHGC), for solar gain during the winter, that’s also an effective insulator (low U-value equals high R-value), and doesn’t cost an arm and a leg?
So who’s really tops? It didn’t take long for GBA readers to dive in with their opinions.
Experience counts, but your mileage may vary
Among the most often mentioned high performance windows are SeriousWindows, manufactured by Serious Materials Inc. of Sunnyvale, California. The windows are made with foam-filled fiberglass frames, suspended films inside the glass, inert gas fill, and high R-values, common attributes in this category of uber efficiency.
Scott Heeschen selected Serious units for a south-facing clerestory and Marvin Integrity units for the rest of the house after getting quotes from…
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