[GBlist] Windows & UV Damage

[Sarah Holland/David Foley <hollandfoley@acadia.net>]

Dear Folks,

We're running some calculations that show us that we can lower the annual
heating needs of a house in Maine by about 18% if we merely switch the
south-facing windows from low-E glass with a low solar heat gain coefficient
to clear insulating glass with a higher SHGC.  (East, west and north glass
would remain low-E.  We haven't yet calculated if this change will increase
cooling loads in summer.)  Making this change is about the only glazing
option available to us with this window manufacturer.  My question is:
where can I find good data on the potential for UV damage to fabrics,
upholstery, etc., from the clear insulated glass?  There's an index, called
the "Krochman Damage Function" which is a percentage of transmission of the
UV spectrum, compared to outdoors.  The number is 64% for clear IG, and 34%
for the low-E glass.  But what does this mean in practical terms?  Would the
owners anticipate much more damage to the contents of the house?  Any
real-world experience or hard data would be appreciated.  Thanks!

- David Foley
-- 
Holland & Foley Building Design L.L.C.
232 Beech Hill Rd.
Northport, Maine 04849 USA
p: (207) 338-9869 f: (207) 338-9859 e: hollandfoley@acadia.net


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