[Equest-users] Calculating Baseline Fan Power

[Grando, John]

If you just start the table with:

BHP      Eff
0           0.825

and set =vlookup(*,*,2,TRUE) you should get the results you want.


John Grando LEED AP| Mechanical Engineer
Phone: 212-615-3705 | Fax: 212-615-3700
jgrando at cosentini.com

Cosentini Associates - A Tetra Tech Company
Two Pennsylvania Plaza - Third Floor - New York, NY 10121
www.cosentini.com<http://www.cosentini.com/>





________________________________
From: Bishop, Bill [mailto:wbishop at pathfinder-ea.com]
Sent: Tuesday, April 06, 2010 5:10 PM
To: Tomlinson, Scott; equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Calculating Baseline Fan Power

Scott,

The note for Table G3.1.2.9 states to use the design flow rate of the baseline building system to calculate A. There is still the issue of whether or not to apply the adjustment from Table 6.5.3.1.1B when the baseline system serves a different area than the proposed system. I'm still trying to decide that as well. I can think of at least two alternatives:
1.)     Apply the pressure drop adjustment to any baseline system that conditions at least half of the area of a proposed system that qualifies for the adjustment,
2.)     Apply the pressure drop adjustment in a weighted manner based on the proportional area conditioned by the baseline system relative to the proposed system.

I think option 1.) would be quicker but option 2.) more closely reflects the intent of the pressure drop adjustment.

On a related note, if anybody has figured out a way to use a VLOOKUP function or equivalent in Excel for looking up motor efficiency in a baseline Pfan calculation, let me know. (The function returns the efficiency of the next smallest motor in the table when there is no exact match, but G3.1.2.9 requires the efficiency of the next largest motor to be used.)

Regards,
Bill

William Bishop, EIT, BEMP, LEED(r) AP | Pathfinder Engineers & Architects LLP
Mechanical Engineer

134 South Fitzhugh Street
Rochester, NY 14608
T: (585) 325-6004 Ext. 114
F: (585) 325-6005
wbishop at pathfinder-ea.com
www.pathfinder-ea.com
P Please strive to live sustainably.
________________________________
From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Tomlinson, Scott
Sent: Tuesday, April 06, 2010 4:29 PM
To: equest-users at lists.onebuilding.org
Subject: [Equest-users] Calculating Baseline Fan Power

eQuesters,

Sorry in advance for a confusing question, but determining baseline system fan power is terribly confusing to me.  I am currently using ASHRAE 90.1 - 2007.

According to section G3.1.2.9 I need to calculate fan power=(bhp*746)/(fan motor efficiency) for a system 7.

According to Table G3.1.2.9 I need to calculate bhp=CFM(s)*.0013+A for a system 7.

According to Table 6.5.3.1.1A I need to calculate A=Summation of [PD*CFM(d)/4131] where:

PD= each applicable pressure drop adjustment from table 6.5.3.1.1B in wc and
CFM(d)= the design airflow of each applicable device from table 6.5.3.1.1B

So basically I take the airflow rates from my design building systems and the pressure drops from my components in my design building systems to figure out what my baseline building break horsepower will be.  What if I have systems serving multiple floors in my design building?  Since 90.1 requires me to have a system per floor in my baseline building how would I handle this?  What if I have systems with different components serving different portions of my design building?

I guess a simpler question would be how are people determining baseline fan power?

Thank you,
__________________________________________

Scott Tomlinson, PE, LEED-AP

Mechanical

Symmes Maini & McKee Associates, Inc.

1000 Massachusetts Avenue, Cambridge, MA 02138

t: 617.520.9438

[cid:905534913 at 07042010-06D4]



f: 617.354.5758

stomlinson at smma.com<mailto:STomlinson at smma.com>

www.smma.com<http://www.smma.com/>





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