Error in glazing system when trying to calculate

[David Freiberg]

I am getting this error when trying to calculate the u-factor using THERM. When I go to options > Preferences > THERM file options, that setting is not there. I am using THERM 8.0. Anyone have any suggestions? 

Thank you, 
David Freiberg

[Robin Mitchell]

That's not an error, it's just informational.

You can control the Boundary Conditions that are used under Options / Preferences / Therm File Options -- there is a checkbox "Check for correct WINDOW boundary conditions on glazing systems" ... you can uncheck that "check" if you don't want that informational message to appear. 

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Robin Mitchell

Building Technology and Urban Systems Division
Energy Technologies Area
Lawrence Berkeley National Laboratory

[David Freiberg]

Thank you for the response!

I just verified that I have that box unchecked, and I do, but that information is still popping up and I am unable to calculate. Does that mean that I must have an undefined boundary condition? Or how do i proceed? 

[Robin Mitchell]

How are your glazing system boundary conditions defined in WINDOW? 

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[David Freiberg]

Hi Robin,

I think that is where the problem is. I am unsure how to define the boundary conditions in WINDOW. I've attached my file as well as a screenshot of how i have the glazing system set up. How do you define the boundary conditions in WINDOW?

Thanks for your help,

David Freiberg

[Robin Mitchell]

In WINDOW, Boundary Conditions are defined in the Environmental Conditions library

The detail view of each Environmental Conditions record, where you define the different conditions for U-factor / SHGC

Then you reference the desired Environmental Conditions record in the Glazing System

Then when you import the glazing system into THERM, you need to add U-factor tags, etc. 

This is explained in the NFRC THERM/WINDOW Simulation manual, linked on both the WINDOW and THERM Documentation pages, but here is a direct link to it

https://cdn.ymaws.com/nfrccommunity.org/resource/resmgr/simmanual/nfrcsim7-jul2024.pdf

Look at page 6-41 for an example of how to set up the BCs in THERM.

Robin

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[David Freiberg]

Thank you Robin,

I've read through the manual, and I thought I was ready to perform my calculations, but I seem to still be having some issues. 

I see the option for the environmental conditions in WINDOW, which would help for the external boundary condition, but the issue I have is when I set the internal boundary condition to "Use existing BC from Library", the software will not let me calculate the u-factors. Please see attached photo. 

Is there a way to allow THERM to calculate u-factor values after manually changing the B.C.s in THERM?

Thank you,
David Freiberg

[Robin Mitchell]

What version of THERM / WINDOW are you running? I tried opening the file you included in THERM 7.8.74, but it is from a different version. 

Could you attach the THMX file, which can be generated with this setting

Robin

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[David Freiberg]

Hi Robin,

Thank you again for all the help. Attached is the THMX file. I am currently using THERM/WINDOW 8.0.33. 

On page 82 of the manual, I found that I was importing the glazing system with the wrong settings for NFRC calculations. I now set the B.C. to NFRC 100-2010 for exterior and "use convection plus enclosure radiation" for the interior. 

I was able to get some values now, but I am a little confused on how to interpret the results.

What value should I be looking at for the u-factor of the system? Also, what boundary conditions should I apply for the rest of the interior faces? 

Thanks again,

David Freiberg

[Robin Mitchell]

Can you attach the revised THM file (not the THMX file).

Robin

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[David Freiberg]

Sorry about that, attached is the revised THM and THMX file.

Thanks again for the help,
David Freiberg

[Robin Mitchell]

David

You should apply the BCs and U-factor tags as shown in this diagram from the Simulation manual. I have made some changes to your THM file, shown below, and it is attached to this thread, with my initials attached to it so you can distinguish it from your original.

In your file, you didn't set the frame with the U-factor tag of Frame, so the U-factor across those surfaces was not calculated, and you were only getting results for Edge, which is the interior glass. I changed that in the attached file.

There was also a small boundary segment on the exterior that was set to Adiabatic and I changed that to the EXTERIOR tag that you had assigned to the rest of the exterior frame surfaces

With those changes, you can now see the U-factors for the Edge, which is the glazing system, and the Frame

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[David Freiberg]

Ohh, that all makes sense. Thank you for clarififying. 

Thank you again Robin and I hope you have the best of days. 

-David Freiberg

[Robin Mitchell]

Feel free to reach out if you have more questions. 

Robin

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[Adella Nov]

Hi,

Can you please clarify why this has gone wrong, as I am receiving the same message: 'The file has glazing system boundary conditions names (which are generated when the glazing system is imported from WINDOW) that do not match the name of the Glazing system. To use the WINDOW-generated Boundary conditions for the Glazing system, regenerate the boundary conditions. To keep the non-window generated boundary conditions for the glazing system, go to Options>Preferences>THERM file Options and change the setting that enforces this rule.'

Using Therm 8.0 I do not have the 'THERM file options'. I've realised every time i use this glazing type it has the same issue.

[Adella Nov]

This is the model

[Collin Robinson]

Hi, the boundary conditions need to have the glazing system name in them to work. I changed that.  I flipped the model so that exterior is at left conventionally, that seemed to help with some of the u-factor tags. 

 I also tagged the glass and spandrel "edge" properly and got it to run. See attached revised file. I hope that helps. 

Collin