[Bldg-sim] Assembly SHGC

[Alex Krickx]

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.


From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Cheney
Sent: Friday, September 17, 2010 9:11 AM
To: D. Charlie Curcija
Cc: Jon Matthews; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Assembly SHGC

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
On Fri, Sep 17, 2010 at 9:03 AM, D. Charlie Curcija <curcija at designbuildersoftware.com<mailto:curcija at designbuildersoftware.com>> wrote:
>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

From: bldg-sim-bounces at lists.onebuilding.org<mailto:bldg-sim-bounces at lists.onebuilding.org> [mailto:bldg-sim-bounces at lists.onebuilding.org<mailto:bldg-sim-bounces at lists.onebuilding.org>] On Behalf Of Jon Matthews
Sent: Friday, September 17, 2010 11:36 AM
To: bldg-sim at lists.onebuilding.org<mailto:bldg-sim at lists.onebuilding.org>
Subject: [Bldg-sim] Assembly SHGC

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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