[TRNSYS-users] TRNSYS and Window 5.2

[David Bradley]

Dear All,
   Those of you who are also subscribed to the BLDG-SIM mailing list 
perhaps saw a discussion last week concerning a bug in the DOE-2 report 
that is generated by Window 5.2. Since this is the same program and same 
output format that is used as the basis of TRNSYS's Type56 window model, we 
thought it might be useful to let you all know that the bug in Window 5 
does not affect our w4-lib.dat file. According to Transsolar:

The Type56 window model does not use the U-values from the DOE2 report. The 
U-value is instead calculated within Type56 as a function of the 
temperature of gas layers within the window. The convective heat transfer 
coefficient is an input either from the .bui file or from an INPUT to 
Type56. The U-value from the DOE2 report is displayed in TRNBuild but this 
value is superceded by the internally calculated value.

The following is the bug report from the BLDG-SIM mailing list:

>Anyone using Window 5 (any version) to create custom glazing for DOE2 
>simulations should be very careful.  There is a bug in the output feature 
>of Window 5 that incorrectly reports the window film coefficients used to 
>calculate the center of glass U-value.  If you use this data in a DOE 2 
>simulation the calculated center of glass U-value may be off by as much as 
>40%.  BE CAREFUL and check the output reports to verify glazing 
>performance if you are importing Window 5 performance data.  Apparently 
>Window 4 does not have this problem, it worked fine when I tried it.

and the reply:

>Thanks for pointing this out. This is a known bug in WINDOW5.  However, 
>you can still use WINDOW5 with a little modification. The methodology for 
>calculating inside heat transfer coefficient was changed in WINDOW5 where 
>radiative and convective part of film coefficients are calculated 
>separately but the DOE2 output report from WINDOW5 only reports convective 
>part.

Kind regards,
   David

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Thermal Energy System Specialists (TESS), LLC
David BRADLEY                           2916 Marketplace Drive - Suite 104
Partner                                        Madison, WI 53719
Phone: (608) 274-2577 USA
Fax: (608) 278-1475
E-mail: bradley at tess-inc.com
Web Pages:  http://www.tess-inc.com     and      http://www.trnsys.com

"Providing software solutions for today's energy engineering projects"
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