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Night ventilation not working

asked 2021-03-26 14:52:28 -0500

Martinsquare's avatar

updated 2021-04-18 13:23:09 -0500

I am trying to implement night ventilation into my energyplus model, but it is not working (no change in air temperatures and energy use, etc.) What I did: image description -In which NightventAvail is a EMS adjusted schedule. The output is 1 during nights in the summer months. Other periods it is 0 (checked the output via output:variables) -In which Officemedium HVACOperationSchd is the HVAC schedule. I used the same schedule as was used in the box of 'Fan Schedule Name' in AvailabilityManager:NightCycle. -In which NightventTemp is an EMS adjusted schedule, which varies between 19.75 and 22.75°C depending on outside conditions (checked the output via output:variables).

The problem is that it is not working. I also tried to assign it in the AvailabilityManager:assignmentList like this:

image description

What I also tried was switch the Applicability Schedule Name to an always on schedule, and switch the NightventTemp to a normal schedule value without the use of EMS. All of this didn't work.

I hope one of you knows what I am doing wrong.

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answered 2021-03-28 16:03:02 -0500

Jim Dirkes's avatar

I don't think this gives enough information to understand why the simulation is not working, so I'll respond with some generic comments:

Have you reviewed the output to confirm that the fan turns on when needed? and is controlling to the proper setpoint? with full outdoor air?

Normally you can "reverse engineer" the input problem by noting which part of the operation is not doing as you expect.

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Thank you for you reaction. I reviewed if all conditions for nightventilation are met.

  • tempertaure difference between in and outside >2°C
  • Inside temperature above specified 'Ventilation Temperature Schedule'
  • Applicability schedule = 1
  • Inside temperture above lower limit

However, the fan's flow rate is 0 kg/s

Martinsquare's avatar Martinsquare  ( 2021-03-29 06:59:43 -0500 )edit

If you're willing to send the IDF, I'm willing to take a closer look.... (

Jim Dirkes's avatar Jim Dirkes  ( 2021-03-29 07:55:05 -0500 )edit

Thank you! I send it to your e-mail.

Martinsquare's avatar Martinsquare  ( 2021-03-29 08:03:27 -0500 )edit

Is there a follow-up on this one? I'm implementing nigh ventilation in EnergyPlus and I'm not sure it's working either. The availability on night ventilation is always zero but the fans are running more at night, although the % OA is not always 100%. what's really interesting is whatever the ventilation temperature low limit is: 15C or 30C, it generates the same result, aka, there results in no impact on night ventilation, so that field is not used....

xfang's avatar xfang  ( 2023-02-28 11:03:29 -0500 )edit

Happy to take a look at your IDF ( If you send it, also describe the sequence of operation that you desire.

Jim Dirkes's avatar Jim Dirkes  ( 2023-02-28 13:14:21 -0500 )edit

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Asked: 2021-03-26 14:52:28 -0500

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Last updated: Mar 28 '21