[Equest-users] Modeling Windows: Center of Glass vs Assembly

[Carol Gardner]

Happy reading. I'm not sure exactly how eQUEST handles all of this but I
would assume, oooh, dangerous, that if you put in your glass type carefully
and take care to specify the width and type of frame you have, all of which
are in the Wizards, you should be good. You could test the output by
comparing it to a Win5 calculation of your COG U value and frame, or just
import the Win5 data into the model.

Carol

On Thu, Sep 16, 2010 at 2:38 PM, STEVE SAMENSKI <
steve at thespinnakergroupinc.com> wrote:

>  Does anyone know definitively if eQuest calculates window assembly
> U-values based on user input?
>
> As many have pointed out, the USGBC is now being careful about the
> distinction between center-of-glass U values and assembly U values.  I’ve
> been entering center-of-glass U-values and precise window geometry, counting
> on eQuest to do the heavy lifting for me.  Report LV-D says “U-VALUE
> INCLUDES OUTSIDE AIR FILM; WINDOW INCLUDES FRAME, IF DEFINED”.  However,
> combing through several posts to this forum, some say eQuest doesn’t really
> calculate an assembly’s U-value, because it ignores the edge-of-glass
> effects due to the frame.  (Not to be confused with the thermal conductance
> of the frame itself, which I’m sure eQuest uses in its calcs.)  I’m hoping
> that one of the programmers can answer this, or maybe someone who got the
> story from a programmer.
>
> I plan to read the ASHRAE Fundamentals Chapter on Fenestration this
> weekend.  Wish me luck.
>
> Steve Samenski, PE, LEED AP, BEMP
> Vice President - Sustainable Technologies
> The Spinnaker Group, Inc.
> http://equest-diary.livejournal.com/
> www.thespinnakergroupinc.com <*http://www.thespinnakergroupinc.com*>
> *Become the solution... Join the USGBC!
> *
>
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-- 
Carol Gardner PE
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