[EnergyPlus_Support] VAV System Part Load Fan Power Curve Difference between DOE Reference Model and STD90.1

[<xukevin24@xxxxxxxxx>]

I noticed there is a difference between part-load fan power equation defined in ASHRAE Standard 90.1- Appendix G (2004/07/10) and the fan curve included in the DOE reference models (e.g. newly built (2004) medium sized office building E+ model) for VAV system. ASHRAE 90.1 seems more conservative on the part load performance. Anyone here knows where DOE reference model get the part-load equation from?
Thanks much!
-Ke Xu, Ph.D., BEMP, BEAP
In DOE reference model for medium sized office bldg:
 Fan:VariableVolume,
    VAV_1_Fan,               !- Name
    HVACOperationSchd,       !- Availability Schedule Name
    0.5915,                  !- Fan Efficiency
    1109.648,                !- Pressure Rise {Pa}
    AUTOSIZE,                !- Maximum Flow Rate {m3/s}
    FixedFlowRate,           !- Fan Power Minimum Flow Rate Input Method
    ,                        !- Fan Power Minimum Flow Fraction
    0.0000,                  !- Fan Power Minimum Air Flow Rate {m3/s}
    0.91,                    !- Motor Efficiency
    1.0,                     !- Motor In Airstream Fraction
    0.0407598940,            !- Fan Power Coefficient 1
    0.08804497,              !- Fan Power Coefficient 2
    -0.072926120,            !- Fan Power Coefficient 3
    0.9437398230,            !- Fan Power Coefficient 4
    0,                       !- Fan Power Coefficient 5
    VAV_1_HeatC-VAV_1_FanNode,  !- Air Inlet Node Name
    VAV_1 Supply Equipment Outlet Node,  !- Air Outlet Node Name
    Fan Energy;              !- End-Use Subcategory
ASHRAE 90.1-2004, 2007, 2010 Appendix G has:
Pfan = 0.0013 + 0.1470 x PLRfan + 0.9506 x (PLRfan)^2 -0.0998 x (PLRfan)^3
where
P fan = fraction of full-load fan power and
PLRfan = fan part-load ratio (current cfmldesign cfm).

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