LEED Increased Ventilation Credit and Energy Modeling

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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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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

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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

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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

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Worth noting that if you are modeling for LEED for Homes Midrise projects, you follow the modified version of Appendix G that appears in the ENERGY STAR Multifamily High Rise Simulation Guidelines, which puts a cap on your baseline ventilation flow rates of no more than 150% of 62.2.

Nathan Miller - PE, LEED(r)AP BD+C, CEM

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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

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Jim,

In my understanding the increased ventilation LEED point was created in
response to a deduction in the required ventilation rates by ASHRAE between
versions of 62.1. The confusion around how this affected the energy credit
came later.

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*

*From:* 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

*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
*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

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Great comments all, and correct for LEED v3.

This is changing in the new LEED v4. It references ASHRAE 90.1 2010 which
does *not *match the baseline Ventilation rate to a proposed design that
exceeds the rates set by the rating authority or building official.

This matches Jim's comments - a high ventilation rate will be penalized
under LEED v4, since the baseline is the minimum, and the proposed matches
the higher value of the design.

Cheers,
Alex

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