Our LEED review of EAp2 seems to indicate that we cannot model the central plant and have to use “purchased chilled water” for both the baseline and proposed. When this change is made all of the enhancements that we have in the central plant are negated and our percentage improvement over the baseline drops. The LEED review states as follows: "Table 1.4.6 indicates that the Proposed Case model is utilizing Option 2 of the Treatment of District or Campus Thermal Energy in LEED v2 and LEED 2009 - Design & Construction (DES v2) dated August 10, 2010 which can be accessed at: https://new.usgbc.org/resources/des-district-energy-systems-guidance-v22.... However, it is unclear whether the Monitoring or Modeling method has been used to determine the average DES cooling efficiency per Appendix C. Revise the model as necessary, provide a narrative, and additional documentation confirming the method used for calculating the average DES cooling efficiency and provide revised simulation inputs reflecting any changes."
Any help in clearing this up will be greatly appreciated!!
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Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
August 26, 2013 - 9:11 am
The segment of the review comment you provided does not indicate you must model the central plant as purchased chilled water. As I recall that review comment will typically provide you with the available options when modeling a central plant (Appendix G, DESv2 Option 1 or 2). Just because it is an option does not mean that you have to model it as purchased chilled water.
The portion of the comment you provided is simply asking which method you used to determine the plant efficiency.
charles bell
principaltheGreenTeam, Inc.
12 thumbs up
August 26, 2013 - 5:46 pm
RE: campus energy plant.
Our engineers are concerned and say as they read the comment and the document referenced in the comment, there is a floor or minimum number of points required to use option 2. The minimum is 6 points that we do not have, we only have 4; so do we have to use option 1? That is according to the LEED review comment.
Thanks,
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
August 26, 2013 - 6:18 pm
If you do not meet the minimum number of points you have to use Option 1 or use Appendix G and treat the chilled water as purchased energy. Both options are identical in their implementation but Option 1 has a point cap.
charles bell
principaltheGreenTeam, Inc.
12 thumbs up
August 29, 2013 - 11:30 am
We have input the purchased chilled water, but we cannot find how to model the more efficient plant (proposed chiller efficiency vs. base chiller efficiency). We have reviewed input fields and on-line help (user manual), but cannot find how to adjust the purchased chilled water to account for the differing efficiencies.
Has anyone in your group encountered this condition and if so, how were they able to resolve it?
Thanks,
Marcus Sheffer
LEED Fellow7group / Energy Opportunities
LEEDuser Expert
5907 thumbs up
August 29, 2013 - 1:56 pm
Under option 1 you do not include any efficiency difference since you are treating the chilled water as purchased energy and are not accounting for the plant efficiency.
DESv2 Option 2 provides the methodology to use for determining the efficiency (see Section 2.4.1.2.1, 2.4.1.2.3 and Appendix C) of the baseline and proposed plants. This is only used if applying under this option.