E+ DOAS Night Cycle Control and FourPipeFanCoil MultiSpeedFan Control Questions

asked 2020-04-30 00:40:20 -0500

RyanCGuan gravatar image

updated 2020-04-30 11:32:05 -0500

Hi folks,

This is an office building w/ DOAS to provide pre-conditioned outdoor air and cooling only FCU is ducted to DOAS. If there is no cooling load, the FCU is operating at the minimum fan speed, but boost up to meet the cooling load. Local heating is provided via electric baseboard.

In EnergyPlus 9.0 model, the FCU+baseboard configuration was simplified as ZoneHVAC:FourPipeFanCoil w/ electric heating coil. the ZoneHVAC:EqupmentList at thermal zone is defined to have DOAS as sequence 1 and FCU as sequence 2. I ran into the following issues:

  1. The ZoneHVAC:FourPipeFanCoil w/ electric heating coil can't be set as "MultiSpeedFan" w/ Supply Air Fan Operating Model Schedule, which allow the FCU to operate at the minimum speed when no cooling load and max speed when cooling load occue. The error message indicates the heating coil is missing. If I switch the heating coil to be hot water heating, the error is gone. I will add the error message later. Have any of you run into this similar issue? Do I have to use the hot water heating in ZoneHVAC:FourPipeFanCoil to active the MultiSpeedFan?
  2. The actual design use FCU and baseboard to night cycle first. If the load isn't met, the DOAS will be operated to meet the rest load. This sequence is opposite to the occupied period sequence set up in the energy model. My understand of the ZoneHVAC:EquipmentList is DOAS need to be set as 1 and local equipment need to be set as 2. Otherwise, there is potential unmet hours issue. Do you have any work around to make the design work? The DOAS is fairly large, and DOAS night cycle w/ 100% outdoor air will cause triple heating energy.

I will follow up with the error message mentioned in #1. Also, if the idf is needed, I can re-generate it with a simple office geometry.

Thanks for any inputs.

-Ryan

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Comments

@RyanCGuan new issue 8025 posted for the electric heating coil problem.

MJWitte gravatar image MJWitte  ( 2020-05-29 17:54:31 -0500 )edit