Pollination to Ironbug: Failed to add all airloop demand components!


I believe there might be a bug in Ironbug because I am getting some strange behavior between Pollination and Ironbug.

I am using the Ironbug 1.6.1 and running into the below error:

Failed to add all airloop demand components!

Here’s what caused it and then I’ll describe how it was solved:
Like the video in this post, I was connecting PO Rooms directly to the Ironbug grouped template HVAC and then plugging it into the new DetailedHVAC component, and then into ModelToOSM. The model simulated but the Ironbug HVAC was not present in the OSM file (check via OpenStudio Application).

I then tried the other method of Ironbug’s SaveToFile and received the error message above. Note I made no changes to the template file. I also tried with just 3 rooms from Pollination and received the same error. I looked in the Ironbug grouped HVAC and everything seems fine.

The solution but only partially
I discovered through trial and error that if I plug the PO Rooms into a HB component first, such as IdealAir, then into the Ironbug HVAC Template, and lastly into the SaveToFile component, the output OSM model was correct.

However, if I use the DetailedHVAC method, the OSM file does not contain the Ironbug HVAC at all.


  1. From my perspective, PO Rooms to Ironbug directly does not work without putting it through some HB components first.
  2. The DetailedHVAC component doesn’t seem to be working at all. Requiring the SaveToFile method to still be used.


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Hey @justinshultz ,

I think @mingbo might have just pushed a fix for this yesterday. Can you try installing the latest version of the Rhino plugin and see if you still have the issue?

The problem seems to be partially fixed. The DetailedHVAC component worked for basic systems. I’ve now created a system using the AirTerminalSingleDuctInletSideMixer component to couple a Four Pipe Fan Coil unit to the DOAS air stream, and it has stopped work. The DetailedHVAC component had an object reference error in the terminal window and the OSM generated has no HVAC systems in those zones. When using the SaveToFile method, the OSM file and HVAC systems were fine.


Hi @justinshultz could you please provide a simple sample file for me to debug?

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Hi @mingbo, below is my file.


  1. OSM file not generated with Ironbug HVAC components when using DetailedHVAC component. Could be the SingleDuct:Mixer with FourPipeFanCoilUnits.
  2. ModelToOSM is running the full simulation despite Run = 2.

ProposedEnergyModel_forMingbo.gh (523.0 KB)

Hi @justinshultz, it was indeed related to the special InletAirMixer component. I have pushed a new fix, and a new version of the Pollination installer should be ready in about an hour.