[Bldg-sim] ASHRAE 62 question

[Paul Erickson]

Vikram,

Good question...a bit interesting to try and answer.

First, your calculations are correct.

Second, it is interesting that only "educational science laboratories" are mentioned, somehow suggesting that their use is different from corporate and institutional labs.

Third, EH&S often makes this determination and there is no agreement among standards/guidelines dealing with lab ventilation so to impose this bit of Std 62 seems like something that the USGBC should be considering as it moves towards connecting Appendix G to Std 62 rates.

Fourth, related to that last point, while Appendix G does not yet directly require Std 62 rates for the baseline, LEED requires Std 62 rates for the proposed and 90.1 requires the baseline ventilation to match the proposed.  So, it would seem that models should be reflecting the 1 cfm/sf requirement.

There is a grey area that I think may also be a point of discussion.  Minimum exhaust rates of various types are often only required when the space is occupied.  As such, and considering that many university EH&S folks are at least beginning to bat around the notion of, if not adopt, a 4 ACH minimum during unoccupied periods, it seems fair to have a value lower than 1 cfm/sf during unoccupied periods.  What's your perspective on this?

It'd be good if others chime in and help develop a consensus.

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 Sami, Vikram
Sent: Tuesday, August 24, 2010 10:49 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] ASHRAE 62 question

Just going through table 6.4 in ASHRAE 62.1-2007 it looks like the minimum exhaust rates for labs (educational science laboratories) is 1 cfm/ft2. That amounts to an ACH of 6 (for a 10ft ceiling) and 6.7 for a 9ft ceiling.

Am I interpreting that correctly? Does that mean for LEED projects we cannot go below 6 - 7 ACH? Is there a way around it?


Vikram Sami, LEED AP
Sustainable Design Analyst
1382 Peachtree St. NE, Atlanta, GA 30309
t: 404-443-7462    f: 404.892.5823       e: vikram.sami at perkinswill.com<mailto:vikram.sami at perkinswill.com>   www.perkinswill.com<http://www.perkinswill.com/>
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