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RE: GBlist: high performance on-site window test




> 3.  Unless you are only building in Canada, you had better look at OTHER
> performance parameters as well, including Solar Heat Gain Coefficient, air
> leakage, durability, warranty, etc.

> 5.  ALSO, if you get REAL control on these projects, consider looking into
> glazing systems that are optimized for the orientation and function expected!
>  Passive solar?  High clarity on the south and appropriate storage proximity.
>  A lot of West glazing with a view?  Consider High Tvis with low SHGC.  Etc.

I've been finding this to be much easier said than done.  I'm trying to
get this type of information to select windows for the south side of
my New England house.  Thanks to NFRC when I ask for whole-unit R or U value
I get it.  When I ask for the solar heat gain coefficient (SHGC) they don't 
know.  I've been able to get this information for a couple different brands of
windows, but that's it.  It's next to impossible to comparison shop
R-value and SHGC values.

I was at my local lumber yard yesterday selecting a large window.  The person
giving me information had never heard of SHGC and told me that he usually
deals with builders and of course they don't care.  He called the company
directly for me, but the salesman didn't know either so we got a technical
support number.  They didn't know and gave us the number of their labs who
did give us the SHGC.  This is typical of the difficulty I've had in getting
SHGC for glass.

I went to a home show once hoping to get window information.  Of about 10
installer/dealers there, only one had heard of NFRC ratings.  One guy even
told me that his hollow vinyl framed windows have a higher whole unit R-value
than the R10 center of glass, because of the amazing insulation properties
of his vinyl.  As you could easily guess he'd never heard of the NFRC.

/carl
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