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How to model a multiple level air treatment ?

asked 2023-11-14 15:15:11 -0500

updated 2023-11-15 12:38:24 -0500

I'm working on an existing building and I would like to know the best way to model his HVAC systems, more specifically the air distribution systems of the building according to their treatment levels. Level 1 brings outside air into the building via AHU 1 and 2 air handling units. They allow energy recovery from the exhaust air thanks to a thermal wheel coupled to a recovery coil. In addition, these AHUs are equipped with cooling coils to dehumidify and precondition the air during the summer. Level 2 conditions mixed air, i.e. a mixture of outside air and return air. This level includes fan coil units (VC) types 1, 2 and 3. AHU 1 is for VC 1 and 2, while AHU 2 is for VC 3. Both AHUs are 100% outside air. The air is mix in the mecanicals room of each stage of the building. I tried to model these systems on OpenStudio. First I've created 2 air loop with the above described equipments for the outside air. then I put Unit:ventilator as they are the VC 1, 2 and 3. But as I understand EnergyPlus simulated sequentialy the zone equipment to meet the internal gain. Thus I think my model does not represent the reality. Do you have any idea how I can improve my model ? image description

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answered 2023-11-15 18:44:04 -0500

Keigo's avatar

How to model PAU connected to multiple AHUs

AirLoopHVAC:DedicatedOutdoorAirSystem example?

I think OpenStudio does not cover AirLoopHVAC:DedicatedOutdoorAirSystem. You can model it with EnergyPlus. You should use the latest version EnergyPlus as it is a relatively new feature and there were many bugs before (You can find my previous posts in this site).

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thank you very much @Keigo's avatar  ( 2023-12-06 09:38:25 -0500 )edit

answered 2024-03-08 08:03:17 -0500

zimje7's avatar

There's not much documentation on it but AirLoopHVAC:DedicatedOutdoorAirSystem is available in OpenStudio. I was able to get it to work(mostly) in 3.4.0. It's not available in the GUI, so I set everything up using measures. There do seem to be a couple bugs. The total OA flow for the DedicatedOutdoorAirSystem is supposed to be the sum of the max OA flow rates of all the OA systems for the connected loops, but I could only get it to size correctly by multiplying the max OA flows by a factor of 1.19. I also was unable to get the system to function properly with a relief fan. I used some posts on github and the sdk documentation to help with the setup.

Link to OS object: https://openstudio-sdk-documentation....

Github link:

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Asked: 2023-11-14 15:15:11 -0500

Seen: 157 times

Last updated: Mar 08