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

[James Hansen]

“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.”

 

Ron, please educate me if I’m reading your email wrong, but are you saying that your occupancy schedule in the proposed design does not match the baseline design?  This is strictly prohibited in App G I thought…  You can change schedules to take advantage of non-standard ECMs like DCV, and automatic lighting reductions for the use of occupancy sensors (in rooms NOT already required to have them by code).  But having a conference room 100% occupied from 7am-6pm in the baseline model and only 100% occupied from 9am-noon in the proposed model is not a valid way to demonstrate savings from DCV, since there will be energy savings related to the people latent/sensible production that has nothing to do with DCV.  Don’t you have to create a minimum outside air schedule to demonstrate DCV savings?  If you have received credit for simply reducing the Occupancy Schedule in the proposed model, that is very interesting…

 

Thanks!

 

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 <http://www.ghtltd.com/> 

 

 

From: ron lamarre [mailto:lamarre_arch at yahoo.com] 
Sent: Tuesday, July 27, 2010 2:08 PM
To: James Hansen; equest-users
Subject: Re: [Equest-users] Demand Controlled Ventilation and EA Credit 1

 

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 <http://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

 

 

 

________________________________

The information contained in this communication is confidential, may be privileged, and is intended only for the use of the addressee.  It is the property of GHT Limited.  Unauthorized use, disclosure or copying of this communication or any part thereof is strictly prohibited and may be unlawful.  If you have received this communication in error, please notify me immediately by return e-mail or by e-mail to ght at ghtltd.com <mailto:ght at ghtltd.com> , and destroy this communication and all copies thereof, including all attachments.  Thank you. 

 


The information contained in this communication is confidential, may be privileged, and is intended only for the use of the addressee.  It is the property of GHT Limited.  Unauthorized use, disclosure or copying of this communication or any part thereof is strictly prohibited and may be unlawful.  If you have received this communication in error, please notify me immediately by return e-mail or by e-mail to ght at ghtltd.com, and destroy this communication and all copies thereof, including all attachments.  Thank you.



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