Window verification – glazing specs
johnandsue
| Posted in General Questions on
We are building a small home in W Virginia . we have designed some passive solar elements for it .
The windows for the southern side came in and are nailed up but not sided in yet.
I checked the sticker on these windows and it doesn’t match the specs.for the order , the sticker has .15 u and .27
solar heat gain. The order called for .21 u and .46 solar heat gain. The company is Fibertec and I called and they said they are just wrong lables and that the windows are as per the specs. Is there a way to verify
the they are correct ? these windows are a key part of our pass solar design.
any suggestions on what to do ? (they are paid for)
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Replies
your help is appreciated
There are a few tools that can be used to measure glass characteristics, but it will be hard to find anyone who owns them (although a window company might)--check out http://edtm.com/index.php/glass-inspection-tools/shgc-indicators for an example. You are more likely to find someone who has something like the GC3000, but that only gives you general categories on the coating types, it does not identify exactly which coating is there. You might be able to narrow it down that way. You can call and talk to them, explain your issue, and see what they say.
There is sometimes enough information stamped on the spacer bar(s) to identify the glass used, but it can be a research project.
And then there are lab tests for verifying glass characteristics, but I think they're out of range for most of us.
Your issue is a tough one. I would have a hard time believing that the sticker was wrong, but I guess that would depend on the explanation I was given. Did they tell you specifically why they think the wrong stickers were used?
And I guess since someone's going to ask, how to you know that the better u-factor isn't a decent trade-off for the lower SHGC?
Doesn't Fibertec manufacturer their own glazings now ??
Will be harder to certify as they will probably be protective.
john sereday: did they tell you the glazings are their own or from a 3rd party?
David: products should be as ordered, even if a diff could do a similar job... not acceptable .
Couldn't John measure insolation/radiation ( don't know the correct term )
difference from exterior of the window and interior within a few minutes and compare
solar power ? maybe a light meter with frequency specific measurements could be used also
there is a large difference between the 2 SHG values ...???