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Does Rated Fan Power in EnergyPlus Include Motor Efficiency?

asked 2016-04-22 11:27:56 -0500

pflaumingo's avatar

updated 2016-04-22 11:42:53 -0500

I've been looking at the rated fan power of single speed fans (Fan:OnOff and Fan:ConstantVolume) reported by EnergyPlus and comparing it to hand calculations I've noticed that it doesn't seem to include motor efficiency. Has anyone else noticed this? Is the motor power consumption reported elsewhere? My understanding was that rated fan power should include motor efficiency.

Example: Fan efficiency = 42.75%, Pressure rise = 226.92 Pa, Flow rate = 0.090613 m^3s^-1, Motor efficiency = 85.5%

Hand calculation = 56.25 W, Hand calculation w/o motor efficiency = 48.098 W, EnergyPlus rated fan power = 48.098 W

I got the EnergyPlus value from the SQL file and the html file.

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answered 2016-04-22 11:48:36 -0500

updated 2016-04-22 11:48:54 -0500

Yes it does. The efficiency input in the fan object includes motor and fan efficiency. See the answer to Fan motor replacement savings

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That's right. I was using OpenStudio and the input is labelled 'Fan Efficiency' rather than 'Fan Total Efficiency' like EnergyPlus so I mistook it for static efficiency. Just posting this comment in case anyone else interprets it the way I did.

pflaumingo's avatar pflaumingo  ( 2016-04-22 11:59:33 -0500 )edit

An issue has been filed to clarify this input in OpenStudio.

ericringold's avatar ericringold  ( 2016-04-22 12:13:02 -0500 )edit

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Asked: 2016-04-22 11:27:56 -0500

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Last updated: Apr 22 '16