[Trace-users] Appendix G Fan Energy

Bob Vogt BVogt at luckett-farley.com
Thu Oct 29 04:59:11 PDT 2009


As you know there are many ways to model fan energy. I normally use the
Apply ECB/PRM rules under the Change Energy Parameters tab for the
baseline building. Trace somehow accounts for the Appendix G
requirements. I do not modify airflows, I let Trace keep track of those.

For the proposed building sometimes I make a fan selection at the
desired static, divide the selected kw by the cfm and static pressure
and input the results in the systems fan tab by inputting the static
pressure and Full Load Energy Rate units of kw/cfm-in wg.

Can your system use a system exhaust in lieu of a return fan?

Hope this helps.

Bob Vogt

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Today's Topics:

   1. Appendix G Fan Energy (Snarski, Marty)


Message: 1
Date: Tue, 27 Oct 2009 13:33:28 -0500
From: "Snarski, Marty" <msnarski at shwgroup.com>
To: <trace-users at lists.onebuilding.org>
Subject: [Trace-users] Appendix G Fan Energy
	<078AC5207CEDE145A8C7C74FFB3975A05470DE at DALEXC1.shwgroup.com>
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Hello, all.


I'm running an energy model (for LEED), and am having a particular
problem with the Fan Energy results.  I am using the actual fan
horsepower (for the supply and for the return fans) for the proposed
building, and the Appendix G equation in G3.1.2.9.  The results I'm
getting for the proposed design are considerably higher (about 31%) than
the baseline building.  This leads me to believe that I may be
misinterpreting the equation.  


As stated in the 90.1 Users manual, the equation accounts for supply,
return, relief, and exhaust fans.  However, I've been simply inputting
the Supply CFM into the equation.  Given that it accounts for all fans,
should I use the accumulated CFMs for each of those fans (i.e. if I'm
supplying 32,000, and returning 24,000, should I use 56,000 cfm)?


While I understand TRACE has the automatic baseline fan sizing
capability, I'm not sure I trust it completely, and would like to know
where the calculation comes from.


Thanks for any help you can offer!

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