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How to control inlet air temperature and humidity in Natural ventilation.

asked 2018-11-07 15:19:16 -0600

Haohan Sha gravatar image

updated 2018-11-07 17:23:11 -0600

I'm looking forward modelling the cooling effects caused by natural ventilation. To ensure the indoor thermal comfort, I wish to use natural ventilation only when outside temperature is in 12-21 degree and the outside humidity should be less than 80% on the night(0:00-7:00).

So I have two questions 1. in airflow network, it cannot set outside temperature range and humidity, and So I add a (EMS) to control this. However, how can I control the time?
2. I found that when I use the (EMS), the previous settings in the Airflownetwork:MultiZone:Zone do not work. For example, although I set the Venting Schedule in Airflownetwork:MultiZone:Zone, when the outside conditions satisfy the conditions in EMS, the Venting Schedule is ignored. How to avoid this?

The code is following.

Thanks for any assistance.


EnergyManagementSystem:Sensor, ZoneT, !- Name Thermal Zone: The atrium 1, !- Output:Variable or Output:Meter Index Key Name Site Outdoor Air Drybulb Temperature; !- Output:Variable or Output:Meter Name


EnergyManagementSystem:Actuator, MyOpenFactor1, !- Name Bottom Vent, !- Actuated Component Unique Name AirFlow Network Window/Door Opening, !- Actuated Component Type Venting Opening Factor; !- Actuated Component Control Type

EnergyManagementSystem:Actuator, MyOpenFactor2, !- Name Top Vent, !- Actuated Component Unique Name AirFlow Network Window/Door Opening, !- Actuated Component Type Venting Opening Factor; !- Actuated Component Control Type


EnergyManagementSystem:ProgramCallingManager, TControlled Open Factor, !- Name BeginTimestepBeforePredictor, !- EnergyPlus Model Calling Point T_OpeningController; !- Program Name 1


EnergyManagementSystem:Program, T_OpeningController, !- Name , !- Program Line 1 IF ZoneT < 12, !- Program Line 2 SET MyOpenFactor1 = 0.0, !- A4 SET MyOpenFactor2 = 0.0, !- A5 ELSEIF ZoneT > 21, !- A6 SET MyOpenFactor1 = 0.0, !- A7 SET MyOpenFactor2 = 0.0, !- A8 ElSE, !- A9 SET MyOpenFactor1 = 1.0, !- A10 SET MyOpenFactor2 = 1.0, !- A11 ENDIF; !- A12

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answered 2018-11-28 10:43:09 -0600

Haohan Sha gravatar image

For the first question: This problem has been solved by adding a new senor(for example Vent_schedule) in the venting schedule(you need to define this schedule at first), and use this senor as a condition in the EMS:Program. Just add a condition: if vent_schedule==0 then : set openfactor=0

With this method, the airflow network opening can be controlled by the venting schedule.

Next: the EMS can override the venting schedule in define, so the only way to control the opening by time is the method above.

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answered 2018-11-07 20:41:22 -0600

Check the line-by-line results in the edd output file to see if the program is working as expected. The sensor object looks wrong, because the key name for Site Outdoor Air Drybulb Temperature should be "Environment", not a zone name. The program above looks similar to example file EMSAirflowNetworkOpeningControlByHumidity.idf.

Another option is to use AvailabilityManager:HybridVentilation which can be used to control natural ventilation with AirflowNetWork or ZoneVentilation and it has limits for max/min outdoor dry-bulb and wet-bulb temperature.

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it's same to use environment or the zone name in EMS. I checked the example file, but it cannot judge whether the EMS make the venting schedule useless. I want to operate the vent only on the night, and so I set a venting availability schedule. But the EMS seems ignore this schedule, and change all the opening factors =1.0 when it satisfies the conditions.

Can Availability:Manager be used alone in Natural ventilation without mechanical ventilation or HVAC system?

Haohan Sha gravatar imageHaohan Sha ( 2018-11-07 21:26:47 -0600 )edit

Yes - AvailabilityManager:HybridVentilation should work without an HVAC system. It will disable ZoneVentilation:* or AirFlowNetwork venting in the specified zone.

MJWitte gravatar imageMJWitte ( 2018-11-15 12:49:34 -0600 )edit

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Asked: 2018-11-07 15:19:16 -0600

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Last updated: Nov 28 '18