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

[STEVE SAMENSKI]

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.  I¹ve
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 ³U-VALUE
INCLUDES OUTSIDE AIR FILM; WINDOW INCLUDES FRAME, IF DEFINED².  However,
combing through several posts to this forum, some say eQuest doesn¹t really
calculate an assembly¹s 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 I¹m sure eQuest uses in its calcs.)  I¹m 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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