Modeling Displacement Ventilation in OpenStudio or EnergyPlus, High Energy Consumption

asked 2015-05-20 15:57:22 -0500

updated 2017-08-07 13:22:08 -0500

I am having issues showing energy savings for displacement ventilation in an OpenStudio model. I wrote a E+ script that changes the RoomAirModelType to ThreeNodeDisplacementVentilation and the RoomAirSettings:ThreeNodeDisplacementVentilation object to the following:

RoomAirSettings:ThreeNodeDisplacementVentilation,
  Zone, !- Zone Name
  DV Gain Distribution Schedule,          !- Gain Distribution Schedule Name
  1,                                      !- Number of Plumes per Occupant
  1.0668,                                 !- Thermostat Height {m}
  1.0668,                                 !- Comfort Height {m}
  0.3;                                    !- Temperature Difference Threshold for Reporting {deltaC}

with the DV Gain Distribution Schedule defined as follows:

Schedule:Compact,
  DV Gain Distribution Schedule,          !- Name
  ,                                       !- Schedule Type Limits Name
  Through: 12/31,                         !- Field 1
  For: Alldays,                           !- Field 2
  Until: 24:00,                           !- Field 3
  0.20;                                   !- Field 4

I set my VAV airloop to 62-68F supply air temperature and assign the sizing supply air temps accordingly.

When I do all this I am showing drastically higher fan energy use. I see some cooling savings, but they are nominal compared to the fan energy increase. It appears that the gain distribution schedule is not being applied, and that because the supply air temperature is higher, the system has to provide more and more air to meet the loads. I assume that the displacement ventilation should be resulting in fan and cooling energy savings. I have compared my models to the example displacement ventilation E+ files and cannot figure out what the issue is.

Has anyone successfully modeled displacement ventilation in E+ or OpenStudio? If so, do you have any tips or do you know what I am missing that is causing this issue? Any help is greatly appreciated.

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Comments

@TaylorRoberts have you found any resolution for this?

Eric Ringold gravatar image Eric Ringold  ( 2016-03-15 09:04:44 -0500 )edit

I have a similar issue and I was wondering if you were successful. thanks

ramyask gravatar image ramyask  ( 2016-11-03 14:43:43 -0500 )edit
MatthewSteen gravatar image MatthewSteen  ( 2017-05-11 11:19:23 -0500 )edit