[Equest-users] EPACT 179d ventilation reiqurements

Steve Jacobs sjacobseng at gmail.com
Mon Oct 22 11:43:36 PDT 2012

That's been my process also. I've worked on some older buildings that have
little or no ventilation. The tax incentive rewards their poor IAQ.

- Steve

On Mon, Oct 22, 2012 at 11:48 AM, Patrick J. O'Leary, Jr. <
poleary1969 at gmail.com> wrote:

>  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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