[Equest-users] irs 179d guidelines

Patrick J. O'Leary, Jr. poleary1969 at gmail.com
Fri Dec 16 14:55:34 PST 2011

i'm currently looking at the requirements for modeling a building to 
demonstrate energy savings per the epact 2005/irs 179d requirements & am 
trying to determine the proper method for calculating baseline fan 
power.  has anyone else done this yet?

per the NREL manual, Appendix G Section, Wording Changes and 
Corresponding Sections in Standard 90.1-2001:

"G3.1.2.9 Supply Fan Power:  The Reference Building model fan power 
shall be determined based on § in Standard 90.1-2001"

in 90.1-2001 section is the section with the table that lists 
how to calculate the allowable system fan power.

my question is, "for epact 2005/irs 179d energy modeling is the correct 
supply fan power to use in the baseline building the same as the 
allowable fan system power?"  this seems odd when comparing it to 
90.1-2004 and having to calculate a baseline fan power (table g3.1.2.9) 
in lieu of using the fan power limitation ( and plugging that 
number into the equation Pfan listed in section g.3.1.29.  it sort of 
just seems too easy.


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