[Equest-users] EPACT 179d ventilation reiqurements

Patrick J. O'Leary, Jr. poleary1969 at gmail.com
Mon Oct 22 10:48:16 PDT 2012

i have followed the 62-1999 rates for the baseline.  as the epact 
requirements state the 90.1-2004 app g method has been modified to meet 
the requirements of epact.  this is one the differences.  it is my 
understanding that where there is a difference between epact 
requirements and 90.1-2004 modeling requirements the epact requirement 
takes precedence.

On 10/22/12 10:35 AM, Steve Jacobs wrote:
> Hi everyone,
> I have a question about the ventilation requirements for 179d 
> modeling. The NREL guidelines state to use 62-1999 for the baseline 
> and the actual rates for the proposed building. I'm so use to modeling 
> ventilating rates the same in both models I wanted to make sure I'm 
> interpreting this correctly. I've been doing separate 62 calculations 
> per ASHRAE 62-1999 for the baseline. This can make a significant 
> difference in the OA rates between the baseline and proposed. The 1999 
> rates are higher than the 2004/2007 rates for some building area 
> types. Also, if the baseline model is a VAV system with a critical 
> zone driving the OA rate, the difference can be even greater.
> How have you guys handled this situation?
> On a separate note, has anyone done epact for building on a central 
> plant. Obviously it is not covered by the NREL guidelines, so it seems 
> like it is on the engineer to come up with a reasonable interpretation.
> - Steve
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