the atrium is modelled by floor, solving the adjacency on the floor to create air boundaries, and solving adjacency on the interior walls for them to also become air walls.:
When I place any apertures on the outside of the atrium, the energy model doesn’t work:
If I completely remove the windows from the atrium the model is working fine. the problem seems to be the airwalls created for each floor of the atrium.
Sorry that I didn’t see the original question until now. What you are seeing here is a limitation of the EnergyPlus Construction:AirBoundary object that we use for all AirBoundary Faces in Honeybee.
This object is pretty powerful compared to what we used for air walls in Legacy Honeybee in that the Construction:AirBoundary allows for both solar and radiant heat transfer across it:
This makes the energy simulation a lot more accurate, especially when it comes to modeling interior surface temperature (very important for comfort mapping):
But it’s still a relatively new EnergyPlus feature and E+ will freak out if you give it a case where a Room is composed entirely of AirBoundaries except for one Face that has a window. The E+ team just hasn’t yet been able to get the solar/radiant heat transfer calculation to be correct for this case, though they’ve been making progress. For example, they recently removed the error that was thrown in the case of all Room Faces being composed of AirBoundaries:
The best way to work around the limitation right now is to just join Rooms together into one if there’s a situation where one of the Rooms is composed entirely of AirBoundaries except for one Face with a window. For your case with an atrium here, I would not split the atrium up vertically. Maybe, if you want, you can split it up horizontally with one perimeter zone and a deeper core zone. But the vertical splits are not going to make your model anymore accurate and you should have the floor of the atrium in the same Room as all of the windows.
This reminds me that I have been meaning to add a validation check into the HB Validate Model component, which identifies all of these AirBoundary cases where E+ might freak out. I have opened an issue for it so that I don’t forget about it:
But that validation check should make these cases much easier to identify and help you work around the E+ limitation.
Thank you Chris.
The reason why I want to divide the atrium up vertically is because I consider that the area above is not air-conditioned. I want to see the impact on indoor load in this situation.
My current approach is to adjust the parameters of the enclosure structure of the inner wall of the upper space, but I still feel that this is not quite correct.
In that case, you can probably still divide the atrium in two vertically. You’ll just divide it around where you’d expect the stratification height would be. As long as you have at least one other Face of the Room (eg. Roof or Floor), I think the EnergyPlus should succeed. Let me know if you find otherwise.
I have added a validation check for these cases that can cause EnergyPlus to fail:
The change should be available via the LB Versioner shortly.
So, now, if you want to know whether your model has any of these cases of air boundaries that could cause a simulation failure, the HB Validate Model component can tell you exactly where these cases exist in your model.
