[Equest-users] Interpretation of Appendix G3.1.2.2 for unmet hours

[Dakota Kelley]

My experience has always been that the 50-hour difference is applied separately to heating and cooling hours, so the Difference column in the example below would be out of compliance.  The 300-hour limit is applied to each model, so the Difference row in the example would be in compliance.  

 

To reduce Baseline unmet hours, I prefer to leave the cooling/heating coil factors as set by Appx G but gradually increase the minimum CFM/SQFT for the affected zones.  I agree that is theoretically possible to adjust sizing factors to eliminate unmet hours, but I argue against this approach in my long-winded discussion of this topic below:

 

http://lists.onebuilding.org/htdig.cgi/equest-users-onebuilding.org/2010-January/003024.html

 

(See sections 5.b.i and 5.b.ii)

 

I would apply this approach to your Baseline heating and Proposed cooling air flows to achieve compliance.

 

Thanks,

 

 

  
                

DAKOTA KELLEY 

Project Designer | Energy Analyst

                          

                              Office: 214.744.6199                 

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From: Patrick J. O'Leary, Jr. [mailto:poleary1969 at gmail.com] 
Sent: Tuesday, July 13, 2010 1:35 PM
To: equest-users at lists.onebuilding.org
Subject: Re: [Equest-users] Interpretation of Appendix G3.1.2.2 for unmet hours

 

i've wondered that before.  i had a review comment several years ago on a leed 2.1 project where the reviewer disagreed with the concept that the overall unmet load hours were fine as i had a spread similar to yours in the heating or cooling unmet hours.  i ended up increasing cmf and/or capacity until they were more in line with each other.  

i never did receive a better clarification though, and the 90.1 user manuals only show an example with 0 unmet hours so it is pretty useless in that regard.

On 7/13/10 11:28 AM, Brett Fero wrote: 

Has anyone received LEED reviewer comments regarding the fine-line interpretation of Appendix G3.1.2.2 for unmet hours.

 

I think I meet the criteria as shown in the table below.

 

 

 

The unmet loads in either model is less than 300.

The unmet loads of the proposed building does not exceed the Baseline building by more than 50.

 

There does not appear to be a requirement regarding the breakdown of heating and cooling unmet hours.

 

I know I could tweak the over-sizing factors, but am I correct in thinking that these results satisfy AppendixG3.1.2.2 for unmet hours?

 

 

Brett Fero, P.E., LEED AP

RobsonWoese Inc.

Syracuse, NY 13212

 

 

 
 
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