Crashing Issue in OpenStudio When Accessing Thermal Zone Tab

[eliaseid1]

Hi there,

I'm experiencing consistent crashes in OpenStudio whenever I try to access the thermal zones tab. This issue arose after I included natural ventilation and an exhaust fan in a kitchen I'm modelling (as zone equipment). Could you please provide assistance? I've ensured that I have the latest updates for both OpenStudio and EnergyPlus. I can provide the OSM if someone can help please.

Thanks in advance.

[macumber]

@eliaseid1 sent the OSM in question and the issue was a OS:ZoneHVAC:EquipmentList with objects of priority 1, 3, 4 (missing priority 2). @eliaseid1 if you can provide steps to reproduce the issue when building a model, we can try to fix it

[eliaseid1]

Dear Dan,

I appreciate your response and apologize for the delay in getting back to you. During this time, I have been attempting to recreate the bug. After conducting various tests, I have successfully identified the issue:
-Initially, I added a CV Unit Heater gas (OS:ZoneHVAC:UnitHeater).
-Following that, I integrated a natural ventilation system (OS:ZoneVentilation:DesignFlowRate).
-Subsequently, I included an exhaust fan (another OS:ZoneVentilation:DesignFlowRate).
-Lastly, I removed the CV Unit Heater gas in order to experiment with adding a different type of heater. It was during this step that the bug occurred. Specifically, upon navigating to another tab and returning to the thermal zone tab, OpenStudio crashed.

I suspect that the problem may be related to the OS:ZoneVentilation component as well, particularly because the crash did not occur when only the CV Unit Heater gas was present.
I really hope you can solve the issue.
Thank you for your continued assistance.

Best regards,
Elias

[macumber]

Thanks @eliaseid1, in your model the third zone equipment named "Exhaust Fan" is actually a schedule. I'm not sure how you added that to the zone equipment list? I can't drag a schedule to that location. Can you share how you did that?

[eliaseid1]

Hello Dan,
I am not sure how you are able to observe the exhaust fan in the zone equipment, which is strange.
When I access my OS model, the exhaust ventilation appears within the zone equipment, not the exhaust fan as part of a schedule. I've attached a picture of the model for reference.

[macumber]

@jmarrec I can't reproduce this, can you?

[eliaseid1]

@macumber I've just noticed that the screenshot you shared depicts the old OSM model. In my last email of Thursday, I provided you with two OSMs: one before encountering the bug and another immediately after. Could you please confirm whether you received the email and attempted to address the issue using these two models?
Thank you!

[jmarrec]

Where do I find the "faulty" (before) model? I don't see it on the OSC email.

Also, what do you mean by "before the bug" and "another immediately after". Did you change anything in between or just reopened it?

Did you ever edit the model by hand / outside of the OpenStudioApplication?

[eliaseid1]

Hello Julien,

I appreciate your response. Dan requested that I replicate the bug for you to address, which is why I generated two versions of the file: one before the bug and one after. The sole difference between the two is removing the CV unit heater from the zone equipment in the model after, which triggers the bug.
Furthermore, I made no edits to the model outside of the OS Application.

I believe Dan has the two models, if you don't have them, I'm more than happy to provide them.

Thank you for your help.

[macumber]

I put the files in the issues repo for this issue @jmarrec. I just now saw the second set of files you sent, the before and after osms are the exact same. However, I can reproduce the bug by opening Kitchen Domestic (before removing the CV unit heater).osm and deleting the unit heater. @jmarrec I can look into this tonight if you don't have time.

@eliaseid1 are you able to reproduce this issue if you start a model in OpenStudio Application 1.7.0? Or does it only occur if you build the model in OpenStudio Application 1.5.0 and then upgrade it to OpenStudio Application 1.7.0?

[macumber]

I think this is an OpenStudio issue, there is an assertion failing in ZoneHVACEquipmentList_Impl::removeEquipment when the unit heater is removed.

      for (const auto& elem : coolingVector) {
        boost::optional<ModelExtensibleGroup> eg = getGroupForModelObject(elem);
        OS_ASSERT(eg); // <-- THIS IS FAILING
        eg->setUnsigned(OS_ZoneHVAC_EquipmentListExtensibleFields::ZoneEquipmentCoolingSequence, priority);

        priority++;
      }

[eliaseid1]

Hi @macumber ,
I indeed attempted it in Openstudio 1.7.0, and unfortunately, I encountered the same bug. Additionally, it's important to mention that this issue did not occur when the Natural and exhaust ventilation were not added. This implies that I could freely use and remove the CV unit heater without encountering any issues. So, the crashing in Openstudio somehow is related to this OS:ZoneVentilation:DesignFlowRate.

[eliaseid1]

Another observation I made while reviewing the model: Yesterday, I encountered what seems to be another bug. When attempting to use an electric baseboard convective heater as a zone equipment, I opted for autosize for the heater capacity. However, despite this setting, I consistently received a 0 W output and no heating in the kitchen. Interestingly, manually specifying a value for the heater capacity resolved the issue. It appears that Openstudio considered the autosizing of this component as 0 W. I hope this information proves helpful.