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EnergyPlus Crashes When Adding Windows to Rotating Building Model Using Site:VariableLocation

asked 2025-10-26 02:38:21 -0600

Ammar De's avatar

updated 2025-10-26 11:13:04 -0600

I have been experimenting with the Site:VariableLocation object in EnergyPlus to simulate a rotating building where orientation changes dynamically (e.g., monthly). To test it, I started with the VaryingLocationAndOrientation.idf example file and modified it to represent a simple building with windows instead of a vessel with "underwater" boundary conditions (idf v9.1 can be found here link text).

At first, EnergyPlus kept crashing during simulation with a blank .err file. After some debugging, I found that removing the FenestrationSurface:Detailed objects allowed the simulation to run without crashing. I tried substituting with the Window object too, but it was still crashing. It seems that there could be a conflict between dynamic orientation and solar/optical calculations for transparent surfaces but not opaque surfaces?

Testing using EnergyPlus v25.1:

Interestingly, when testing the same setup in EnergyPlus v25.1, the simulation only crashes if more than one window is present. If there's just a single window, the simulation runs without crashing. To explore this further, I compared the output variable "Surface Outside Face Incident Solar Radiation Rate per Area [W/m2]" between two cases: one with a fixed 90° orientation using the Building object, and another with a 90° dynamic rotation using Site:VariableLocation. The results for the surface hosting the window surface showed significant differences between the two cases. However, when the window was removed (i.e., all surfaces are opaque), the results aligned better suggesting that the dynamic orientation may not be consistently applied to fenestration surfaces.

Also, I noticed something potentially confusing in the example file: the field order appears to be shifted compared to the IDD documentation. For example, the name field is being used to pass a schedule for latitude.

  Site:VariableLocation,
    VaryingLatitude,         !- Name
    VaryingLongitude,        !- Building Location Latitude Schedule
    VaryingOrientation,      !- Building Location Longitude Schedule
    ;                        !- Building Location Orientation Schedule

Has anyone:

  1. Confirmed if this is a known limitation or bug?
  2. Used Site:VariableLocation with windows successfully? or found a workaround?

Thanks!

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Comments

1

EnergyPlus should never crash. And I can confirm the Name field is being incorrectly ignored, it's in the IDD/documentation but not the IDF sample file. I don't see any existing bug reports about this object, so please issue a bug report at https://github.com/NREL/EnergyPlus/is...

shorowit's avatar shorowit  ( 2025-10-27 10:31:37 -0600 )edit

Thanks for the response. I created this issue: https://github.com/NREL/EnergyPlus/is...

Ammar De's avatar Ammar De  ( 2025-10-27 15:44:54 -0600 )edit

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answered 2025-11-21 14:47:56 -0600

Ammar De's avatar

I opened a GitHub issue regarding this, and a related pull request was approved and merged and is now officially included in EnergyPlus v25.2. I have confirmed that in this version, the simulation no longer crashes when multiple window surfaces are present. So the fix resolves both 1) the field ordering issue in the Site:VariableLocation object and 2) the crashing behavior with fenestration. Thanks to the contributors for the quick response and fix.

However, the fix does not address the functional discrepancies observed when comparing fixed vs. variable orientation models that include windows. I plan to open a new issue to track it separately.

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Asked: 2025-10-26 02:38:21 -0600

Seen: 254 times

Last updated: Nov 21