Purchased Chilled Water Pumps

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Hi All,
I seem to get hung up on the basics.
Our project has purchased chilled water from a campus energy plant. The Proposed design does not have CHW pumps as the system is pressurized.
Any thoughts would be helpful.
Many thanks!

Jeff Ross-Bain, BCxP, BEMP, LEED Fellow, MSc
President

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Jeff Ross-Bain3's picture
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Joined: 2011-09-30
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Hi Jeff,
The USGBC provided a guidance document for district thermal energy systems that should be helpful to you. The latest version is now 9 years old, but if you are modeling to 2010 Appendix G, it should be useable.
https://www.usgbc.org/resources/des-district-energy-systems-guidance-v22-and-v2009-guidance-v20

Regards,
~Bill

William Bishop, PE, BEMP, BEAP, CEM, LEED AP
Senior Energy Engineer

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Bill Bishop's picture
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Hi Bill,
And thanks for the quick response.

LEED V4 has added new requirements that reflect ASHRAE 90.1-2010. Previously LEED had Path 1 and Path 2 (per the document you referenced). Now, there is Path 1, 2, and 3, where Path 2, and 3, are the same as before, and Path 1 now refers to ASHRAE 90.1-2010 Appendix G and only applies to buildings where there is both purchased cooling and heating.
What I failed to mention is that we have both district cooling AND heating on this project.

So to reframe the question, per 90.1-2010, Appendix G, with purchased chilled water and heat, should the Baseline include a CHW pump even though the Proposed design does not have CHW pumps. 90.1-2010 language was a bit vague to me regarding that point.

Regards,

Jeff Ross-Bain, BCxP, BEMP, LEED Fellow, MSc
President
Charleston: 843-779-9229
Atlanta: 404-220-8955
RBGB

Maximizing Building Performance.

Jeff Ross-Bain3's picture
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Hi All,
To add an update to this, and after more research from Bill's insights, I have probably answered my own question...

It looks like the 90.1-2010 Appendix G approach (per LEED V4 Path 1) should NOT include upstream equipment efficiencies or power. Therefore, the Baseline model should exclude the CHW pumps as these are, in fact, upstream equipment. Furthermore, the LEED Energy Performance Calculator specifically states in its explanatory notes to not model Baseline pumps if there are none in the actual (Proposed) building.

It's great when one little nudge pushes you in the right direction.

Thanks!

Jeff Ross-Bain, BCxP, BEMP, LEED Fellow, MSc
President
Charleston: 843-779-9229
Atlanta: 404-220-8955
RBGB

Maximizing Building Performance.

Jeff Ross-Bain3's picture
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Joined: 2011-09-30
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