[Equest-users] Demand Controlled Ventilation and EA Credit 1

[ron lamarre]

Hi Karen:

I would suggest that you include the original GBCI "Clarification Required" 
comment and their technical advice within the body of your letter.  Then, state 
the root issue and suggested resolution.  This way LEED will know the specific 
issue that raised this concern.

With regard to the specific LEED comment that started this debate; the LEED 
reviewer may be "wrong" or "testing" the modeler.  I've responded to some LEED 
review comments with an explanation of the models and their final review 
accepted the models as originally submitted. 

In this case, it may make sense to e-mail GBCI with the explanation before 
submitting the EAc1 template for final review.  They allow you to submit 
questions, which they then forward to the review team for further 
clarification.  I think if it's stated that the proposed & baseline design 
ventilation rates are the "....same, as required by LEED, page, verse, etc..." 
and the DCV credit is "....taken utilizing a different occupancy schedule 
between the two models, as required by LEED, page, verse, etc..."; then the LEED 
reviewer will either accept this or will have to provide a further explanation 
of what they now require.  Especially if you also ask them to send you the LEED 
requirement for utilizing the ASHRAE 62.1 minimum where-ever DCV is used; 
instead of utilizing the same rates between the baseline and proposed as 
documented in the LEED reference manual, page.....

Each model that I've done for LEED utilizes the same ventilation rates between 
the proposed and design; whether it was ASHRAE 62.1 or IMC 2003; however, the 
occupancy schedules changed in spaces where DCV was installed.

Having said all this, I've never worked on a project where an Owner has thought 
it was a good "energy-efficient / green" idea to provide more outdoor 
ventilation than required by code (the increased ventilation point); especially 
in a space where the engineer would require DCV to make sure the space is not 
over ventilated. 

Hope this helps.
 
Ron Lamarre, AIA, NCARB
Architect - LEED AP BD+C

Design  +  Energy Modeling + LEED Administration





________________________________
From: Karen Walkerman <kwalkerman at gmail.com>
To: equest-users <equest-users at lists.onebuilding.org>
Sent: Tue, July 27, 2010 12:10:27 PM
Subject: [Equest-users] Demand Controlled Ventilation and EA Credit 1


All,

below is a draft letter to the EA Credit 1 TAG chair.  I welcome any edits, or 
critiques, and if anyone would like to be a co-signer of the letter, please let 
me know.

Thanks,

--
Karen


It has come to our attention from a posting on the eQuest list-serve that a 
fellow energy-modeling professional has been asked to model proposed design and 
baseline design ventilation rates differently where the proposed design model 
utilizes demand controlled ventilation.  We have searched the ASHRAE 90.1 
documentation as well as the LEED reference documentation and consistently find 
the requirement that baseline ventilation rates be modeled the same as the 
proposed design, and that credit can be taken for demand controlled ventilation.

We understand that large energy savings can be gained from demand controlled 
ventilation and that in certain cases, 'gaming' of the system could result in 
abnormally high ventilation rates for the baseline design, while the DCV system 
keeps ventilation rates low in the proposed design, however, our main concern is 
that energy modelers are being made aware of changes to guidelines during the 
design review process.  At this stage, the energy modeler has already completed 
a significant amount of work in preparing the proposed and baseline design 
energy models, and all associated documentation.  Changing the baseline design 
ventilation rates requires re-modeling of the building and increases the 
likelihood that the project will have to challenge a 'rejected' result if the 
LEED reviewer is not satisfied with the energy modeler's response and modeling 
changes.

We feel that it may be time to develop modeling guidelines for demand controlled 
ventilation, and that these guidelines should be developed, released, and 
required in a similar fashion to the district energy guidelines published by 
LEED for NC 2.2  Furthermore, we feel that any changes made to EA Credit 1 
energy modeling guidelines should be made with adequate notice to the energy 
modeling community.

Thank you for your consideration on this issue,

--
Karen Walkerman
Second Law


      
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