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I think you mean to be referencing ASHRAE 90.1-2004
addendum ac not addendum r which includes two new methods for calculating
fan power limits. The first looks at total Motor HP which isn't very
useful for energy modeling purposes and the second looks at fan
brake-horsepower. The fan brake-horsepower equations
are "(CFM x 0.00094) + A" and "(CFM x 0.0013) + A" for
constant volume and variable volume systems respectively. CFM is the
design airflow rate and A is the brakehorse power adjustement for various
pressure drop adjustments given in Table 6.5.3.1.1B.
Mike
Michael Tillou, PE,
LEED
Tillou Engineering,
LLC
Williamstown, MA
01267
P:
413-458-9870 C:
413-652-1087 From: BLDG-SIM@xxxxxxxx [mailto:BLDG-SIM@xxxxxxxx] On Behalf Of Andrew Craig Sent: Wednesday, October 24, 2007 11:56 AM To: BLDG-SIM@xxxxxxxx Subject: [BLDG-SIM] New Calculation method for Baseline Fan Energy in Addendum R I was wondering if anyone out there
can explain the new calculation shown for baseline fan brake horsepower in Table
G3.1.2.9 of Addendum R to ASHRAE 90.1-2004? At first glance, the equation
doesn’t make sense because you are subtracting a relatively small number
(0.0013+A) from a large number (CFMs) leaving you with a ridiculously large
baseline fan motor brake horsepower. Am I just reading this wrong or is
there a typo? Isn’t there an easier way out there to calculate baseline
fan energy (please see version 1 of Appendix G for another confusing
calculation)? Andrew
Craig, EIT, LEED® AP | Mechanical
Designer INTERFACE
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