[Equest-users] ASHRAE 90.1 Appendix G ventilation when fan cycling

Bishop, Bill bbishop at pathfinder-ea.com
Wed Mar 7 07:28:41 PST 2012


Thanks for the reply Aaron. I think Section 6.4 strongly implies, if not requires, Appendix G/LEED models to have zero ventilation during unoccupied hours, per your (our) logic. My particular case is a dormitory with proposed system of DOAS w/zonal induction units. I will verify the anticipated system fan schedule (which might be 24/7 when class is in session) but if there is any unoccupied fan cycling, the proposed design will be 100% OA and it might not meet any of the ASHRAE 90.1 exceptions. I could keep the baseline PTACs with the same ventilation rate during unoccupied hours but the actual cumulative ventilation rate will then vary with the number of hours of fan cycling, which will vary between the baseline and proposed cases due to envelope differences. Therefore, the G3.1.2.5 requirement cannot really be met (which is another reason to argue for no ventilation during fan cycling).

Bill


From: Dahlstrom, Aaron [mailto:ADahlstrom at in-posse.com]
Sent: Wednesday, March 07, 2012 10:06 AM
To: Bishop, Bill; Equest-users at lists.onebuilding.org
Subject: RE: ASHRAE 90.1 Appendix G ventilation when fan cycling

Bill - an excellent question, one I haven't looking into too much before...

Here's a little logic, though:

1.      All LEED buildings are required to meet Section 6.4 in its entirety. (per the pre-requisite language)

2.      The ventilation rates are required to be identical between the proposed and baseline per G3.1.2.5

3.      If there is a reason why the proposed building would need ventilation during unoccupied hours, both the proposed and the baseline shall have ventilation during those hours per G3.1.2.4

I think that's enough logic to make the case for what you've proposed. Thoughts?

Aaron

Aaron Dahlstrom , PE, LEED(r) AP
In Posse - A subsidiary of AKF| 1500 Walnut Street, Suite 1414, Philadelphia, PA 19102
d: 215-282-6753| m: 267-507-5470| In Posse: 215-282-6800| AKF: 215-735-7290
e: ADahlstrom at in-posse.com | in posse web: www.in-posse.com<http://www.in-posse.com/> | akf web: www.akfgroup.com<http://www.akfgroup.com/>



From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Bishop, Bill
Sent: Tuesday, March 06, 2012 5:02 PM
To: Equest-users at lists.onebuilding.org
Subject: [Equest-users] ASHRAE 90.1 Appendix G ventilation when fan cycling

I seem to recall that, when fans are cycled during unoccupied periods per G3.1.2.4, ventilation should be zero - at least in the baseline. I have done this before in eQUEST by setting a MIN-AIR-SCH to zero during unoccupied hours. I can't find any reference to this requirement in Appendix G. However, in the mandatory provisions section 6.4.3.4.3 Shutoff Damper Controls, "Ventilation outdoor air dampers shall be capable of automatically shutting off during preoccupancy building warm-up, cool down, and setback..." (There are exceptions I'm not listing.) Is the general rule that Appendix G and/or LEED models have zero ventilation during unoccupied periods?

Thanks,
Bill

[cid:image001.png at 01CCFC4C.00248850]<mailto:wbishop at pathfinder-ea.com>



This e-mail may contain information that is confidential, privileged or otherwise protected from disclosure. If you are not an intended recipient of this e-mail, do not duplicate or redistribute it by any means. Please delete it and any attachments and notify the sender that you have received it in error. Unintended recipients are prohibited from taking action on the basis of information in this e-mail. E-mail messages may contain computer viruses or other defects, may not be accurately replicated on other systems, or may be intercepted, deleted or interfered without the knowledge of the sender or the intended recipient. If you are not comfortable with the risks associated with e-mail messages, you may decide not to use e-mail to communicate with In Posse.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120307/e0a04fb2/attachment-0002.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 21646 bytes
Desc: image001.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20120307/e0a04fb2/attachment-0002.png>


More information about the Equest-users mailing list