# Assembly SHGC

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Hello All! I am confused to the formula that I found recently in the forum?on
Assembly SHGC. I think its SHGCassembly = 0.08 + (0.86)(SHGCglass) (cant find it
now in the forum but I think it is something like this) which gives me?a higher
assembly SHGC of glass. Is this correct? I thought that assembly SHGC will be
smaller than the SHGC of glass.

Thanks again to all!!

Jon

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Joined: 2011-10-02
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>From this formula, it can be concluded that SHGC of frame is assumed to be
0.57, which is high. Very high. However, the formula may be provided for
default (punitive) value if it does not have NFRC rating. This is to
encourage people to get accurate NFRC values.

Charlie

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Joined: 2011-10-01
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When you use WINDOW to calculate total window SHGC, you will find the SHGC
will be reduced compared as the glaze one. It looks reasonable to me since
the impact of window frame has been considered. From this point of view,
the equation is not always correct.

Cheney

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Joined: 2011-10-02
Reputation: 200

I also calculated a frame SHGC of 0.57 (the formula is an area-weighting formula) and was surprised by that number (seems high).

The formula also assumes 86% of the opening is glass and 14% of the opening is frame. This certainly will vary. From a calculator I have, this would line up with a Kawneer 1600 curtainwall system using 3'x3.5' pieces of glass. I would think, you'd be more likely to see 3'x5' or 4'x6' which have 88% glass and 91% glass areas, respectively.

Using that formula, if you have a COG SHGC of 0.7, your assembly SHGC will go down. If you have a COG SHGC of 0.2, it will go up.

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Joined: 2011-09-30
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