[Equest-users] window, framing combined U-value

[Byron Burns]

Hello John,

 

I found some information that may be useful to you in the DOE2
Engineering manual.  As you can see in the screen shot below there is a
general explanation the algorithm, and in step three they specify the
use of the U-value and the outside film coefficient, which I think is
causing the variation with your reported window U-Value.  eQUEST/DOE2
does the same thing with exterior wall reported U-Values as well.  

 

http://doe2.com/download/DOE-21E/DOE-2EngineersManualVersion2.1A.pdf

 

 

 

 


Byron D. Burns, EIT, BEMP 



From: equest-users-bounces at lists.onebuilding.org
[mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of John
Shen
Sent: Wednesday, October 24, 2012 8:38 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] window, framing combined U-value

 

 

I am wondering if this method seems appropriate for determining the
U-value of glazing combined with framing. For my purposes I am not
concerned with meeting LEED criteria I am just wondering if there is
anything that is wrong or overlooked with this method.

 

Method:

Based on whatever information I have on the window I recreate it the
best I can in WINDOW 6.3 which allows for SHGC values at different
angles as well as a combined U-value which can be put into a DOE2
report. However eQUEST will only import the glazing information (haven't
found a way around this) which gives me the SHGC at different angles
based on glazing however the U-value does not include framing. So, I go
back into WINDOW 6.3 and tell it to generate a detailed report which
tells me the combined U value of glazing and framing among other things.
I then go into my eQUEST .inp file and edit the U value in the Glass
type code.

 

"Exterior Glazin" = GLASS-TYPE-CODE 

   DESCRIPTION      = *Exterior Glazin*

   NLAYER           = 2

   GAPS-THICK       = ( 12.7, 0, 0, 0 )

   GAPS-COND        = ( 0.02407, 0, 0, 0 )

   GAPS-DCOND       = ( 7.76, 0, 0, 0 )

   GAPS-VISC        = ( 1.722, 0, 0, 0 )

   GAPS-DVISC       = ( 4.94, 0, 0, 0 )

   GAPS-DENS        = ( 1.292, 0, 0, 0 )

   GAPS-DDENS       = ( -0.0046, 0, 0, 0 )

   GAPS-PR          = ( 0.72, 0, 0, 0 )

   GAPS-DPR         = ( -0.0002, 0, 0, 0 )

   TSOL             = ( 0.245, 0.246, 0.243, 0.238, 0.231, 0.219, 0.191,


         0.139, 0.064, 0, 0.204 )

   TVIS             = ( 0.638, 0.642, 0.633, 0.621, 0.605, 0.572, 0.5,
0.362, 

         0.168, 0, 0.532 )

   ABS-1            = ( 0.216, 0.219, 0.223, 0.226, 0.226, 0.227, 0.234,


         0.236, 0.191, 0, 0.223 )

   ABS-2            = ( 0.016, 0.017, 0.017, 0.017, 0.017, 0.017, 0.017,


         0.015, 0.011, 0, 0.016 )

   RBSOL-HEMI       = 0.392

   RBVIS-HEMI       = 0.205

   SHDCOF           = 0.303

   PANES-TIR        = ( 0, 0, 0, 0, 0 )

   PANES-EMIS-F     = ( 0.838, 0.84, 0, 0, 0 )

   PANES-EMIS-B     = ( 0.018, 0.84, 0, 0, 0 )

   PANES-THICK      = ( 5.7, 5.7, 0, 0, 0 )

   PANES-COND       = ( 176.6, 175, 0, 0, 0 )

   U-CENTER         = 2.155  <<<<<<<<<<<<<<<<<<<<<<<<<<<<<   I CHANGE
THIS !!!!

   GAPS-FILL        = ( Air, Air, Air, Air )

   PANES-ID         = ( 5439, 103, 0, 0, 0 )

   ..

I change U-CENTER to the U value given to me by WINDOW 6.3. Does
everything seem appropriate? I am trying to avoid using simplified
method for glazing.

Also when I run the simulation and look at the SIM report section LV-H
Details of Windows I find the CENTER-OF-GLASS U-VALUE to be much lower
than the value WINDOW 6.3 came up with. What kind of further
calculations does eQUEST do with the U-value I have provided to come up
with the U-value shown in the report?

Any input would be greatly appreciated. Thanks.

 

John

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