OS File Discrepancies

#1

Hi, noticing some odd things with the export to OS.

Firstly, when I open the OS file, it contains old loops that I have deleted in the Grasshopper file.

For example, this Packaged Rooftop VAV system was something that I had put on the canvas from the Ironbug HVAC template systems but deleted. Yet, it is still showing up in the OS each time I export.

Even when I delete the OS file and reexport, the system is somehow remembered… not sure where the information is stored since the components are no longer on the canvas.

Secondly, I get an odd result from the simulation and different results from Grasshopper and simulating the OS file natively.

The results generated in Grasshopper are located in the “ModelToIdf” folder.

Yet when I open up the Open Studio file and resimulate the file in OS, the results are populated in the “run” folder and are different (and more reasonable) than what I get with the “ModelToIdf” results.

#2

@Elliot_Glassman
For the first question: you might have assigned those zones with HB HVAC system somewhere in GH, as Ironbug won’t delete any system if it is already in the model. Ironbug only disconnect those zones from old system if they are assigned with new system.

For second question: if you are just using the same osm file, there shouldn’t be any difference. doesn’t matter where you run the simulation.
One thing I would do, is

  • run and export the osm file from GH,
  • make a copy of this osm file
  • open and run this copied osm in OpenStudio App.
  • open these two osm file in notepad
  • try to find any differences. (you can copy all content to https://www.diffchecker.com/ or https://text-compare.com/ )

Purely from the output table, they look totally different system to me.

#3

Hi Mingbo,

I did assign a system with the HB HVAC component, but when I don’t, it assigns all the heating and cooling to district systems despite my configuration for electric and gas coils in Ironbug. Perhaps I am missing something in the way Ironbug and HB connect together? I have the HVACSystem definition connecting into the HVACSystem input in the modified exportToOpenStudio component.

#4

I have made some progress unraveling this mystery.

When running the file in Grasshopper, the results showed heating and cooling assigned to district systems, with no fan energy. Yet, when I opened up the OS file everything looked correct, and rerunning it gave different results with the heating and cooling assigned to electric and gas columns and fan energy.

I disconnected Ironbug and got an idealized loads system and got the same results as my initial pass with Grasshopper. Is it possible that my exporttoOpenStudio component is not assigning the Ironbug defined HVAC system until after the initial run? Is there some way to fix this? I used to resimulate OS HB component and now the results look fine in GH (although I would not want to simulate twice for each run).

#5

@Elliot_Glassman
Can you create a text box model with these two hvac systems settings for me to recreate this issue?