[Bldg-sim] LEED Increased Ventilation Credit and Energy Modeling

[David Eldridge]

The GBCI approach seems to be aimed at keeping people from gaming the system, more than suggesting designers stick to the 62.1 minimum. Don't add a bunch of extra OA to get the LEED credit, and then claim energy credit from DCV...

One point to contrast to this is that sometimes local codes, guidelines, or even client design standards might have rates higher than ASHRAE 62.1. In this case 90.1 can't contradict the designer's responsibility, and the baseline should have the identical outside air requirement, even if it is higher than ASHRAE 62.1.

62.1 is still a standard that sets the minimum ventilation rates.

As several others have noted there are specific conditions if DCV is used as a strategy to reduce outside air that might override the baseline OA quantity in some of those cases. It would also make sense to me that the baseline could be required to have an identical DCV system in that case and keep the rates the same, but I've never seen that as an official recommendation.

David


David S. Eldridge, Jr., P.E., LEED AP BD+C, BEMP, BEAP, HBDP
Grumman/Butkus Associates



From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Jim Dirkes
Sent: Thursday, March 06, 2014 3:32 PM
To: West, Scott P; 'Karen Walkerman'; 'Joe Chappell'
Cc: 'bldg-sim at lists.onebuilding.org'
Subject: Re: [Bldg-sim] LEED Increased Ventilation Credit and Energy Modeling

I have to say:

*         I have not followed the GBCI closely on this topic,

*         But it seems like the credit was created to "compare and contrast" the benefits of increased IEQ against the known energy penalty.

*         If that's true, then the Baseline should be per 62.1 and Proposed at 1305 of the Baseline.

James V Dirkes II, PE, BEMP, LEED AP
www.buildingperformanceteam.com<http://www.buildingperformanceteam.com/>
Energy Analysis, Commissioning & Training Services
1631 Acacia Drive, Grand Rapids, MI 49504 USA
616 450 8653

From: bldg-sim-bounces at lists.onebuilding.org<mailto:bldg-sim-bounces at lists.onebuilding.org> [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of West, Scott P
Sent: Thursday, March 06, 2014 4:24 PM
To: 'Karen Walkerman'; 'Joe Chappell'
Cc: 'bldg-sim at lists.onebuilding.org'
Subject: Re: [Bldg-sim] LEED Increased Ventilation Credit and Energy Modeling

I have to agree with Karen on this.  For LEED modeling at least, you can model the ventilation rates the same even if they are above 62.1 minimums.  I would add though that you could apply Addendum bj to 90.1-2007 which add an exception to this for ventilation systems that improve air distribution effectiveness (primarily displacement ventilation systems).  I'm not sure if USGBC has ruled on this specifically but they generally allow one to adopt 90.1 addenda as long as you state which ones you're using.  This addendum also adds an exception for DCV similar to what Karen mentioned.

Scott P. West, P.E., LEED AP BD+C, BEAP, BEMP | JACOBS | Mechanical Engineer | Energy & Power Solutions | 817.222.8512 office | 817.897.1882 cell | scott.west at jacobs.com<mailto:rick.zilar at jacobs.com> | www.jacobs.com<http://www.jacobs.com/> | www.jacobs.com/energyportfolio<http://www.jacobs.com/energyportfolio>

From: Karen Walkerman [mailto:karen at secondlaw.biz]
Sent: Thursday, March 06, 2014 2:55 PM
To: Joe Chappell
Cc: bldg-sim at lists.onebuilding.org<mailto:bldg-sim at lists.onebuilding.org>
Subject: Re: [Bldg-sim] LEED Increased Ventilation Credit and Energy Modeling

There has been lots of discussion and misinformation about this in the past.  I believe the current take on this from a LEED perspective is that for each space in the proposed design where ventilation is above the required minimum AND there is demand controlled ventilation, the equivalent space in the baseline design shall be modeled with the minimum required ventilation as per ASHRAE 62.1.  For all other cases, baseline ventilation rates should match the proposed ventilation rates, regardless of whether the proposed design uses an increased ventilation rate or not.

--
Karen

On Thu, Mar 6, 2014 at 3:50 PM, Joe Chappell <JoeC at designengineers.com<mailto:JoeC at designengineers.com>> wrote:
Good day,

I have a question regarding the LEED credit for Increased Ventilation (IEQc2).  This is the credit awarded for exceeding ventilation in all spaces by 30% beyond the ASHRAE standard 62.1 requirements.  It seems obvious that the design model ventilation rates would be those 30% higher than 62.1 requirements.  What then would the baseline model ventilation rates be?

If you strictly follow 90.1 Appendix G, you should always model baseline and proposed equivalent except for when taking credit for demand controlled ventilation.  However, it seems in this case that it could also be argued (by LEED) that you should model the ASHRAE 62.1 required ventilation rates in the baseline model, not those that are 30% higher and therefore pay the energy expense( most climates) for increased outside air.

Does anyone have any experience with LEED on this issue?  Thanks in advance.

Kind regards,
Joe Chappell



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