[Bldg-sim] Check on FCU fan power calculations?

James Hansen JHANSEN at ghtltd.com
Tue Jan 12 09:03:08 PST 2010


Sorry, I meant PTACs....(FCU is the proposed system).

 

And Jonathan informed me that ASHRAE corrected this is a later addendum,
as well as in the 2007 version of 90.1

 

 

From: Rosenberg, Michael I [mailto:michael.rosenberg at pnl.gov] 
Sent: Tuesday, January 12, 2010 12:01 PM
To: James Hansen
Subject: RE: Check on FCU fan power calculations?

 

James,

 

There is no baseline system that uses FCUs, so the fan power calculation
is not applicable to your proposed FCU's.

 

Mike

 

__________________________ 

Michael Rosenberg 
Senior Commercial Buildings Energy Analyst 
ENERGY & ENVIRONMENT DIRECTORATE 

Pacific Northwest National Laboratory 
2032 Todd Street 
Eugene, OR 97405 
(541) 844-1960 
michael.rosenberg at pnl.gov 
www.pnl.gov 

From: bldg-sim-bounces at lists.onebuilding.org
[mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of James
Hansen
Sent: Tuesday, January 12, 2010 8:21 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Check on FCU fan power calculations?

 

I was curious if anyone could confirm their experience with App G fan
power calculations for FCUs vs real life equipment values.

 

For AHUs, VAV boxes, etc, most average equipment consumes power nearly
identical to the fan power calculations of App G.  Usually a little bit
better, but nothing major unless you start specifying ECM motors in VAV
boxes, fan walls for AHUs, etc.

 

But for FCUs:  I've got a project with 100+, and most of them come out
to about 0.0008 KW / cfm per the calculations.

 

However, fairly standard FCU selections (from McQuay, not that it
matters), use about 0.0003 KW / cfm.  That's almost a third of the
energy use, and when the entire building is FCU, it makes a huge
difference.

 

Can someone confirm their experience?  I'm not complaining, but I just
want to make sure there isn't some addendum that changes the fan power
calcs for very low CFM HVAC systems.

 

Thanks!

 

GHT Limited
James Hansen, PE, LEED AP

Senior Associate

1010 N. Glebe Rd, Suite 200

Arlington, VA  22201-4749

703-338-5754 (Cell)

703-243-1200 (Office)

703-276-1376 (Fax)

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

 

 

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The information contained in this communication is confidential, may be privileged, and is intended only for the use of the addressee.  It is the property of GHT Limited.  Unauthorized use, disclosure or copying of this communication or any part thereof is strictly prohibited and may be unlawful.  If you have received this communication in error, please notify me immediately by return e-mail or by e-mail to ght at ghtltd.com, and destroy this communication and all copies thereof, including all attachments.  Thank you.



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