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# What is the source for the VAV fan power coefficients in the DOE Commercial Reference Buildings?

I know they're not Appendix G values, and I can't seem to find a mention of where they're sourced from. An internal NREL project?

Any help would be appreciated!

Edit: For reference, here is a Google Sheets plot of fraction of full load fan power versus fan part load ratio for 90.1-2004 Appendix G and the VAV fans in the Commercial Reference Building Large Office ("new", meeting 90.1-2004)

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Are you looking at the original "reference" buildings or the more recent "prototype" buildings?

( 2016-07-05 20:44:20 -0500 )edit

The original "reference" buildings, specifically the 2004 "New Construction" buildings.

( 2016-07-06 07:32:00 -0500 )edit

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The key sources for fan curves are:

The ones for variable volume fans in the Commercial Reference Buildings use the CEC-2003 reference for "Good SP Reset VSD Fan":

Created by Jeff Stein 5-5-03

These fan curves were developed using the Characteristic System Curve Fan Model developed by Stein and Hydeman. Curves include part load performance of the fan, belt, motor, and VSD.

This is based on a plenum airfoil fan on a system curve through 0.5"

"Good SP Reset VSD Fan" = CURVE-FIT
TYPE             = CUBIC
INPUT-TYPE       = COEFFICIENTS
OUTPUT-MIN       = 0
OUTPUT-MAX       = 1
COEFFICIENTS     = (0.040759894, 0.08804497, -0.07292612, 0.943739823)


Keep in mind that these fan models have a minimum power such that the fan power will always stay above this level regardless of flow percentage.

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Matt! Funny running into you here! The answer and references are much appreciated!

( 2017-07-19 13:34:01 -0500 )edit

If I remember correctly, they came from PNNL working with manufacturers involved with Standard 90.1 committee work. All the fan parameters came from PNNL. Note that the VAV coefficients also approximate modeling static pressure reset and so may be different than the real fan curve.

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Thanks for the info, and the reminder about the curves taking into account static pressure reset. This might be as good as answer as can be expected for now. I'm going to try contacting the email shown on the Commercial Reference Buildings page. If I don't get a response back, I'll end up marking this as answered.

( 2017-07-19 11:32:28 -0500 )edit