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Dehumidifying not working - Open studio help?

asked 2025-10-06 12:20:24 -0500

TheEnergyTutor's avatar

updated 2025-10-07 09:07:55 -0500

Does anyone have a few minutes to tell me why this model isn't dehumidifying to 45%?

https://drive.google.com/drive/folders/1k2uV-TATrLlnYwRejAm_7-cRGPC5uUwY?usp=sharing

it's open studio 1.10 (the latest)

Thanks.

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answered 2025-10-17 02:36:03 -0500

updated 2025-10-17 02:36:50 -0500

It looks like this is just a matter of how -by default- OpenStudio translates the CoilSystem:Cooling:DX object to IDF. By default, the exported object doesn’t include the Dehumidification Control Type (and related fields).

What OpenStudio exports:

CoilSystem:Cooling:DX,
  Two Stage DX Coil With Humidity Control CoilSystem, !- Name
  Always On,                                          !- Availability Schedule Name
  Node 6,                                             !- DX Cooling Coil System Inlet Node Name
  Node 10,                                            !- DX Cooling Coil System Outlet Node Name
  Node 10,                                            !- DX Cooling Coil System Sensor Node Name
  Coil:Cooling:DX:TwoStageWithHumidityControlMode,    !- Cooling Coil Object Type
  Two Stage DX Coil With Humidity Control;            !- Cooling Coil Name

What it needs to be in IDF to enable dehumidification control:

CoilSystem:Cooling:DX,
  Two Stage DX Coil With Humidity Control CoilSystem, !- Name
  Always On,                                          !- Availability Schedule Name
  Node 6,                                             !- DX Cooling Coil System Inlet Node Name
  Node 10,                                            !- DX Cooling Coil System Outlet Node Name
  Node 10,                                            !- DX Cooling Coil System Sensor Node Name
  Coil:Cooling:DX:TwoStageWithHumidityControlMode,    !- Cooling Coil Object Type
  Two Stage DX Coil With Humidity Control,            !- Cooling Coil Name
  CoolReheat,                                         !- Dehumidification Control Type
  Yes,                                                !- Run on Sensible Load
  Yes,                                                !- Run on Latent Load
  No,                                                 !- Use DOAS DX Cooling Coil
  2.0;                                                !- DOAS DX Cooling Coil Leaving Minimum Air Temperature

After adding these fields, it’s “just” a matter of right-sizing capacities, configuring the outdoor air economizer, and setting supply/return airflows. With those tweaks, I’m getting good results (constant 45% RH) using the Barcelona EPW (TMY) file.

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Asked: 2025-10-06 12:20:24 -0500

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Last updated: 2 days ago