E+ Fatal error with exterior shading control via EMS: Convergence error in SolveForWindowTemperatures (NO AFN)

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Hi everyone,

I’m encountering this fatal error when using EMS to control external shadings. Without the EMS shading control, the simulation runs fine, but as soon as I introduce the EMS logic, the simulation crashes.

************* Beginning Simulation
** Severe  ** Convergence error in SolveForWindowTemperatures for window APERTURE_03D2A1E3
**   ~~~   **  During Warmup, Environment=RUN PERIOD 1, at Simulation time=01/01 02:00 - 02:01
**  Fatal  ** Program halted because of convergence error in SolveForWindowTemperatures for window APERTURE_03D2A1E3
...Summary of Errors that led to program termination:
..... Reference severe error count=1
..... Last severe error=Convergence error in SolveForWindowTemperatures for window APERTURE_03D2A1E3

Interestingly, the error does not occur when I set the shading to be interior instead of exterior. In this case, the shading behaves as intended, which also confirms that the EMS is correctly set up.

Since I need to use exterior shading, I tried other approaches to solve the issue, but none were successful:

1. Increased the simulation timestep (up to 60)
2. Used Screen or Blind objects instead of the Shade object
3. Increased the number of warmup days
4. Increased the temperature convergence tolerance value to 0.5 °C
5. Played around with shading properties
6. Removed the EMS control for the faulty window, but the error simply appeared for another window

I mentioned in the title that there is no AFN in my model, as I found this thread that seems to solve the error in that case. Does anyone understand why this error is triggered by the addition of EMS control, even though exterior shadings were already present in the model with a simpler control?

Any advice or suggestions would be greatly appreciated!

Thanks in advance!