Importance of variations in U-Factor and SHGC

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kaydee
Posts: 5
Joined: Thu Feb 16, 2006 4:04 pm
Location: SF Bay Area

Importance of variations in U-Factor and SHGC

#1 Post by kaydee »

Reviewing the SHGC & U factor across retrofit windows, I wonder how much of a difference a 0.1 to a 0.2 difference in these numbers impacts performance.

For example, a typical Anlin Catalina window has

U-factor=0.27
SHGC = .22

Compare that to a Simonton 7300
U-factor = .33
SHGC = .30

In terms of performance in the long run, how much impact does a difference of about 0.12 in the ratings make?
Further, if the cost of the windows is within 20% (the lower rating one being cheaper), then would it make more sense to buy the better rating window over the long run?

-kaydee

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