Pretty good windows and moisture
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I spoke to a contractor today who said that he did not think my “pretty good” double glazed low E Anderson 100 windows intended for our new build were not good enough. He said that any window with less than an R 5 value would not be adequate and may lead to moisture problems. I would like to build a nice house that is not impossibly expensive and I had read in earlier articles that the investment in triple glazed European style windows was probably not worth it. This is a home in Virginia. Does anyone have thoughts on this?
Lisa
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Replies
Lisa,
In your climate, I don't think the investment in triple-glazed European windows is a rational investment. Unless your windows are unusually large, I wouldn't worry. Double-glazed low-e windows with argon will work fine.
Keep your windows shaded by good roof overhangs if possible, and choose low-SHGC glazing for east and west windows. Global warming will make your climate warmer over the coming decades, not colder.
Thanks Martin! We'll put our savings into solar panels.
When you shop for window you will find them rated by U value. R 5 = U.20
I would guess low E 100s are U.28 that is not a bad window for your climate. It is unlikely any window better than U .28 will pay for itself thru energy savings in your climate. Yes the few days a year when the outdoor temp falls into the single digits you will likely get water condensing on the glass depending on your indoor humidity. If you have wood windows or sills, it becomes a task to mop up the water every few hours before the water damages the finish.
Walta
Lisa, the Andersen 100 Series is a low-priced window that strikes me as a pretty good value. The standard glass has a low-E coating, but they offer upgrades that will improve their efficiency for not much money. For example, the Heatlock option is an interior coating that drops U-values to 0.24. And, the entire window is made of their proprietary Fibrex material which, while not as stout as the much more expensive fiberglass, is not wood and therefore doesn't discolor with interior condensation. These windows feel very lightweight and cheap in operation, so they would be out of place in a high quality house. But Andersen stands behind their product, and I have found dealer support to be stellar. Window spec'ing and purchasing can be a fraught endeavor--in many previous Q&A threads about window selection, local dealer support ends up being the deciding factor.
Thank you this is super helpful! We will check out the heatlock option. I was thinking about using Boral trim for window sills inside--seems easier to maintain. Cheers! Lisa