[Equest-users] LEED Increased Ventilation Credit and Energy Modeling

Bishop, Bill bbishop at pathfinder-ea.com
Wed Dec 3 07:26:54 PST 2014

Joe may have been implying that he used different settings for MIN-OA-METHOD between the baseline and proposed models. Presumably, FRACTION-OF-DESIGN for Proposed and FRACTION-OF-HOURLY for the Baseline, which would actually penalize the Proposed if I understand the methods correctly. My understanding is that FRACTION-OF-DESIGN should be used in both the Baseline and Proposed models to meet the intent of ASHRAE 62.1. FRACTION-OF-HOURLY should decrease the OA CFM as the VAV flow decreases, resulting in a decreased ventilation rate at lower supply flows.

William Bishop, PE, BEMP, BEAP, CEM, LEED AP | Pathfinder Engineers & Architects LLP
Senior Energy Engineer

[cid:image007.jpg at 01D00EE3.A7F7E2F0]  [cid:image008.jpg at 01D00EE3.A7F7E2F0]

134 South Fitzhugh Street                 Rochester, NY 14608

T: (585) 698-1956                        F: (585) 325-6005

bbishop at pathfinder-ea.com<mailto:wbishop at pathfinder-ea.com>             www.pathfinder-ea.com<http://www.pathfinder-ea.com/>

[http://png-5.findicons.com/files/icons/977/rrze/720/globe.png]Carbon Fee and Dividend - simple, effective, and market-based.

From: equest-users-bounces at lists.onebuilding.org [mailto:equest-users-bounces at lists.onebuilding.org] On Behalf Of Robby Oylear
Sent: Friday, March 07, 2014 9:47 AM
To: Joseph Lewis
Cc: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] LEED Increased Ventilation Credit and Energy Modeling


Your last bit there about taking credit for constant OA flow from full-load to part-load conditions on a VAV system is a bit of a red flag for me.  The Baseline system should be minimally compliant with ASHRAE 62.1.  ASHRAE 62.1 section requires that ventilation systems shall be designed to be capable of providing the required ventilation rates in the breathing zone including all full- and part-load conditions.  Outside of Demand Control Ventilation scenarios, I would always expect the Baseline and Proposed case to deliver the same outside airflow at all hours.

That being said, I'm not certain how you're actually getting a credit for what you're saying.  What input are you modifying in eQUEST to accomplish proportional outside air flow control?


On Thu, Mar 6, 2014 at 1:48 PM, Joseph Lewis <jlewis at fortierengineering.com<mailto:jlewis at fortierengineering.com>> wrote:
You are going to follow 90.1 Appendix G for the model.  This means both the baseline and proposed design outdoor air flow rates will need to be the same except if you are using demand control ventilation in the proposed and it is not required by 90.1 section 6.

In the case where you have demand controlled ventilation in the proposed and it is not required in the baseline then the USGBC has stated that they would like the baseline to be modeled as compliant with 62.1 without the system level corrections.  There also should not be any temperature difference corrections because the other appendix G rules require your CFM sizing to be based up on a 20 °F delta T.

If demand controlled ventilation is required by 90.1 then it must be modeled in the baseline and proposed with the same design flow.

I personally take credit on my models for where the proposed VAV system has controls to maintain a constant OA flow across from design to minimum supply, by modeling the baseline as just proportional.  I have not been flagged for it, but I also have not found any definitive ruling that what I am doing is allowed.

Joe Lewis
Fortier Engineering

From: Joe Chappell<mailto:JoeC at designengineers.com>
Sent: Thursday, March 06, 2014 3:50 PM
To: mailto:equest-users at lists.onebuilding.org
Subject: [Equest-users] LEED Increased Ventilation Credit and Energy Modeling

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

Equest-users mailing list
To unsubscribe from this mailing list send  a blank message to EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG<mailto:EQUEST-USERS-UNSUBSCRIBE at ONEBUILDING.ORG>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20141203/e3a7f0ad/attachment.htm>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image007.jpg
Type: image/jpeg
Size: 1517 bytes
Desc: image007.jpg
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20141203/e3a7f0ad/attachment.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image008.jpg
Type: image/jpeg
Size: 1647 bytes
Desc: image008.jpg
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20141203/e3a7f0ad/attachment-0001.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image009.png
Type: image/png
Size: 3856 bytes
Desc: image009.png
URL: <http://lists.onebuilding.org/pipermail/equest-users-onebuilding.org/attachments/20141203/e3a7f0ad/attachment.png>

More information about the Equest-users mailing list