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How to turn on the AHU during unoccupied hours?

asked 2016-09-15 09:31:41 -0500

NasimMirian's avatar

updated 2016-09-15 10:11:22 -0500

I am trying to model an office building in EnergyPlus in which AHUs and CHW flow are off during unoccupied hours and they only become On only in case the zones temperature are going above 80 F. (in real building the CHW flow goes ON and OFF, sometimes it is zero)

The AvailabilityManager:NightCycle does not work properly. I do not know the reason (Please help if anyone know how to make it run). So I have to turn ON all the AHUs,Fan and every thing during Unoccupied hours. Is there any other way to avoid that? is there any function of controlling (shutting on/off) CHW and AHUs based on the room temperature in E+?

Do I need to use EMS?


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Why do you think the nightcycle isn't working? Have you checked your zone temperatures on a timestep level and compared with whether the fan is on or not?

Annie Marston's avatar Annie Marston  ( 2016-09-15 09:38:59 -0500 )edit

I am a little bit confused here. When I turn off the AHU and fans (by using AvailabilityManager) during weekend and nights, the NightCycle Does not turn On the fans and system, but when I turn the AHU On (the Fans are Off) seems that fans are working. However the fan electricity profile or CHW profile show a constant consumption rate not an On/OFF shape (because of the cycling run time).

NasimMirian's avatar NasimMirian  ( 2016-09-16 10:32:55 -0500 )edit

AvailabilityManagers basically implement lockout. Systems cannot override the AvailabilityManager off state.

__AmirRoth__'s avatar __AmirRoth__  ( 2016-09-16 10:51:56 -0500 )edit

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answered 2016-09-29 16:24:58 -0500

AvailabilityManager:NightCycle will control the AHU fans. The schedule in the fan object should be 1 during occupied hours and 0 during unoccupied. The same schedule is referenced in the AvailabilityManager:NightCycle object. If this is not working as expected, then compare your inputs with an example file (e.g. RefBldgMediumOfficeNew2004_Chicago.idf). If you cannot figure it out, then we need to see the idf (either here or at the helpdesk).

The chilled water system does not have an equivalent type of availability manager. If you set the chilled water pump control to Intermittent, then the chilled water loop will operate whenever any chilled water coil requests flow.

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Asked: 2016-09-15 09:31:41 -0500

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Last updated: Sep 29 '16