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

[ron lamarre]

Hi James:

For the record, the occupancy schedule refers to the people present within the 
space.  For instance, a space within the baseline (not required by ASHRAE to 
have DCV) would have the max number of occupants for the entire occupied-mode 
schedule; however, the proposed would have the max number of people for only as 
many hours as submitted in the project narrative for FTE usage of the space, and 
a minimum number of people (or no one) for the remaining occupied-mode time.  
Thus we create an occupancy (people) schedule for the space.  During the 
unoccupied mode the fans would cycle as required with no people, no lighting 
(automatic shut off), acting on the heating & cooling loads.  We would 
not install DCV if the occupant loads didn't change during the occupied mode.

We also use general lighting schedules that take advantage of installed 
occupancy sensors, and process load schedules that take advantage of Energy Star 
computers and monitiors.

The HVAC engineer decides the minimum design rate for each space to work 
(heating & cooling) if fully occupied with all the lights, process loads, and 
people during the occupied mode.  This is normally at or above the 62.1 and/or 
other code-required minimums (never below due to the LEED pre-requisite).  
Sharing the reduction schedules placed into eQuest with a template-narrative to 
support the reductions (based on ASHRAE 90.1, Energy Star, etc... %-reductions) 
has been accepted by LEED.

We utilize an integrated design team method, where the engineers and 
I review the models that I construct.  We also get peer reviews when we think 
it's necessary and/or when LEED throws us a curve.  We pay for our peer 
reviews.  I'm confident that anything we've submitted does not prove 
inconsistency within the review of EAc1.
 
Ron Lamarre, AIA, NCARB
Architect - LEED AP BD+C

Design  +  Energy Modeling + LEED Administration





________________________________
From: James Hansen <JHANSEN at ghtltd.com>
To: ron lamarre <lamarre_arch at yahoo.com>; Karen Walkerman 
<kwalkerman at gmail.com>; 

Sent: Tue, July 27, 2010 12:57:21 PM
Subject: RE: [Equest-users] Demand Controlled Ventilation and EA Credit 1


“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.”
 
Ron, that’s an interesting statement in itself – modifying occupancy schedules 
has an impact on the mechanical cooling (not just the cooling associated with 
reduced ventilation air), which isn’t really fair.  Was that approved by GBCI?  
If so, I guess it’s further proof that there is still a lot of inconsistency in 
the review of EAc1.  

 
Karen, I think your letter does a good job of requesting an official “ruling” 
from the USGBC.
 
GHT Limited
James Hansen, PE, LEED AP
Senior Associate
1010 N. Glebe Rd, Suite 200
Arlington, VA  22201-4749
703-338-5754 (Cell)
703-243-1200 (Office)
703-276-1376 (Fax)
www.ghtltd.com
 
 

________________________________

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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________________________________



      
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