<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html><head> <meta content="text/html; charset=utf-8" http-equiv="Content-Type"> </head>Yes IGU will fail after 25 to 30 yrs. Like shingles. Like caulking. But people decided in the 70s they would rather replace these IGUs than not see through the glass. <br/><p>Sent wirelessly from my BlackBerry device on the Bell network.</p><hr/><div><b>From: </b> Reuben Deumling <9watts@gmail.com>
</div><div><b>Date: </b>Thu, 27 Oct 2011 19:22:17 -0700</div><div><b>To: </b><jfstraube@gmail.com>; Green Building<greenbuilding@lists.bioenergylists.org></div><div><b>Subject: </b>Re: [Greenbuilding] passive house in NY</div><div><br/></div><br><br><div class="gmail_quote">On Thu, Oct 27, 2011 at 7:16 PM, John Straube <span dir="ltr"><<a href="mailto:jfstraube@gmail.com">jfstraube@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
Yes several single panes in series fog up in cold weather, which is why we invented sealed units. Also, low e coatings and gas fills offer improvements beyond which just air filled glass can get.<br></blockquote><div><br>
That is actually not the concern of my window-maker friend. His concern, the thermal benefits notwithstanding, is that the high-tech sealed units fail after as little as 20 years and then one no longer has a clear window to look through. <br>
I can't speak to the fogging of two single pane sashes. I don't doubt it could happen, but on my crummy houses original windows plus storm sashes this has never to my knowledge occurred. <br></div></div>
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