[Bldg-sim] Appendix G. laboratory spaces with minimum 5000 cfm exhaust

[Paul Erickson]

Kevin,

I would suggest that the large loop hole created between G3.1.2.10 (itself and exception h) and your interpretation of G3.1.1 (exception d) does not seem synchronous with the trajectory of 90.1 and ASHRAE's overall goal of reducing energy use in buildings.  As I mentioned in my previous post, a few of us (AEI, ASHRAE, Labs21, and NREL)  began a dialogue about this in January hoping to get published clarity via the 90.1 Continuous Maintenance process.  The timing of our comments happened to coincide with committee voting already in progress and no clarification was made.  However, it was discussed that the intent is that the 5000 CFM minimum is in reference to System exhaust rates, not the exhaust rates of a single Space.

If we're not careful and professionally discerning about loopholes like this one (many of which have thankfully been closed due to the efforts of various groups and volunteers through the CM process and committee participation) we are perpetuating the very type of modeling that has led to modeled vs. actual energy discrepancies that have brought so much critique in recent years.

Perhaps your perspective is shared by others and an open discussion on the topic would serve the modeling community well.  Thanks for chiming in.

Regards,
Paul

Paul Erickson  LEED(r) AP
SR. Sustainable Design COnsultant



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From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Kevin Kyte
Sent: Wednesday, August 18, 2010 3:10 PM
To: Bishop, Bill; bldg-sim at lists.onebuilding.org
Subject: Re: [Bldg-sim] Appendix G. laboratory spaces with minimum 5000 cfm exhaust

Bill:

The answer is in the question, "For laboratory spaces..."

Kevin



________________________________
From: Bishop, Bill [mailto:wbishop at pathfinder-ea.com]
Sent: Wednesday, August 18, 2010 2:42 PM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] Appendix G. laboratory spaces with minimum 5000 cfm exhaust

For baseline HVAC system type, ASHRAE 90.1-2007 has the following exception (G3.1.1 d.):
"For laboratory spaces with a minimum of 5000 cfm of exhaust, use system type 5 or 7 that reduce the exhaust or makeup air volume to 50% of design values during unoccupied periods."
Similarly, "systems serving laboratories with exhaust rates of 5000 cfm or greater" are excepted from the baseline energy recovery requirement (G3.1.2.10 h.).

When applying this exception, is it 5000 cfm per space? Per floor? Per building? Per system?

Thanks,
Bill

William Bishop, PE, BEMP, LEED(r) AP | Pathfinder Engineers & Architects LLP
Mechanical Engineer

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