[Bldg-sim] ASHRAE 62 question

Thu Aug 26 15:32:11 PDT 2010

I have taken credit for unoccupied ACH levels in the past, since Appendix G
specific a 50% turndown from peak ACH during unoccupied hours (G3.1.1,
Exception c.). My understanding is that you can take for an unoccupied
turndown above and beyond a 50% reduction from peak.

Also, all of this only applies to systems that are 5,000 cfm or more -
otherwise the baseline building exhaust fan system and operation should be
the same as the proposed design.

Kendra Tupper, PE, LEED AP
Senior Consultant
Built Environment Team

Rocky Mountain Institute  |  T  303-567-8641 |  F  303-245-7213  |
www.rmi.org

On Thu, Aug 26, 2010 at 4:17 PM, Aleka Pappas <APappas at enermodal.com> wrote:

>  When we provide energy design assistance for labs, a significant energy
> efficiency strategy is to try to get the client to really consider
> ventilation requirements and get them down as low as possible.  This can be
> taken further with good focused ventilation strategies.
> After going through this optimization process, though, I really think the
> final modeling has to have the same ventilation airflow rates in the
> baseline and proposed models (for occupied and unoccupied periods).
> Different types of labs will have different ventilation/ exhaust
> requirements; I don't see how 1 cfm/SF could be be applied to all laboratory
> spaces.
> Having more resources to help design teams and clients reduce design
> ventilation rates as much as possible would be really useful....maybe
> there's a way to use 62.1 & Appendix G modeling to encourage this, but it
> would need to be a lot more detailed than 1 cfm/ SF.
>
>  *Aleka Pappas*
>   Building Energy Engineer
>
> *ENERMODAL ENGINEERING, INC.**Inspiring energy and resource efficient buildings.****www.enermodal.com*1325 E. 16th Ave.
> Denver, CO 80218APappas at enermodal.com
> Office: 303.861.2070/ Direct: 720.221.1082
>
>
> On 8/26/2010 2:20 PM, Paul Erickson wrote:
>
>  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® AP
> SR. Sustainable Design COnsultant
>
>
>
> *AEI* | AFFILIATED ENGINEERS, INC.
> 5802 Research Park Blvd. | Madison, WI  53719
>
> P: 608.236.1112 | F: 608.238.2614
> perickson at aeieng.com  |  *www.aeieng.com* <http://www.aeieng.com/>
>
>
>
>
>
> *From:* bldg-sim-bounces at lists.onebuilding.org [
> mailto:bldg-sim-bounces at lists.onebuilding.org<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
> www.perkinswill.com
>
> *Perkins+Will.*  Ideas + buildings that honor the broader goals of society
>
> *[image: 75logo_only.gif]*Years of Design Innovation**
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