THERM 7.8.71 crashing

[Sarah Sinusas]

I'm trying to simulate a model in Therm 7.8.71 and it keeps crashing. It previously ran without issue, but after changing the exterior boundary condition to the extreme temperature of -10.5 F, its no longer simulating. Would love advice about what settings I may need to change or areas to try simplifying. My model is attached.

[Robin Mitchell]

Can you provide the file that DOES simulate, for comparison?

Robin

On Fri, May 9, 2025 at 9:48 AM Sarah Sinusas <sarah...@gmail.com> wrote:

I'm trying to simulate a model in Therm 7.8.71 and it keeps crashing. It previously ran without issue, but after changing the exterior boundary condition to the extreme temperature of -10.5 F, its no longer simulating. Would love advice about what settings I may need to change or areas to try simplifying. My model is attached.

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Robin Mitchell

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

[Sarah Sinusas]

Hi Robin,

It seems to be an issue with the total temperature delta between the interior and exterior boundary conditions. If I change the exterior boundary condition to -4 F, it runs. Or, if I reduce the interior boundary condition to 60 F (and maintain -10.5 F outside) it also runs, but if there is a large enough difference between inside and outside (e.g., 70 F to -10.5 F), it crashes out. I was able to simulate the model at 68 F inside and -6 outside, which will work for my purposes (not exactly what the client wants, but it is still pretty extreme for their location), but I don't know why it won't simulate with the larger difference between interior and exterior boundary conditions.

Thanks!

Sarah

[Hamid BADI]

works

[Sarah Sinusas]

Hi, it looks like you have the exterior temp as +10.5. Does it also work at -10.5F?

Thank you,

Sarah

Sent from my phone

On May 13, 2025, at 12:04 PM, Hamid BADI <badi....@gmail.com> wrote:

works

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<result.png>

[Robin Mitchell]

Also, it looks like this model is flipped. 

In the original THERM file that I have been looking at, the exterior is on the left side of the model. 

In this image, the exterior is on the right side, which is not the normal way that models should be created. 

When I try to run the original model, THERM seems to simulate forever. 

I will probably hand this over to the programmers later this week to try to figure out what the issue is. 

Robin 

To view this discussion visit https://groups.google.com/d/msgid/LBNL-THERM/C6739E0C-A5E8-47D8-B504-EBD33EE1E9A9%40gmail.com.

[Sarah Sinusas]

Yes, agreed. The outside is the top left corner in the model. The right side and the lower left are interior. We found a work around for our client, but would certainly be interested in whatever is found. 

Thank you for your help!

Sarah

[Robin Mitchell]

I am curious what your work around was. Can you share it? 

Robin

[Sarah Sinusas]

We talked to our client about the challenge we were having modeling to -10.5 F and they accepted modeling at -6.6 F as our exterior temperature (the 20-year extreme) and 68F interior. The simulation ran fine with those boundary conditions.

[Robin Mitchell]

Interesting. 

We will definitely look into this. 

Robin

[Hamid BADI]

You right, here the updated calculation.