[Bldg-rate] [Bldg-sim] District Thermal Energy in LEED

Paul Riemer Paul.Riemer at dunhameng.com
Wed May 6 11:27:35 PDT 2009

Seth, Sam, and Eric,
Thank you for weighing in.  I should not have used the word 'plant'.  So please allow me to restate my question.
I know the Step 2 baseline boilers are on-site, but what fuel type and what efficiency?

Appendix G prohibits fuel switching and I cannot find anything in the DES guide that counters that, so on one hand I think I need the same fuel type which means options A or B.
If I chose option A, I have no savings potential and just distribution losses so no heating side reason to do Step 2.
If I chose option B, I am choosing a code efficiency for a natural draft coal/trash fired hot water boiler.  A piece of equipment so far outside the mainstream, I assert that any statement of code efficiency is arbitrary.

Appendix G also requires me to use a boiler efficiency from Ch 6, so on the other hand, I want to choose gas so I can get a code efficiency which is option C.
If I choose option C, the savings will be strongly dependent on the modeled price differential between coal/trash and natural gas.  This is the savings projects really achieve and why they use coal/trash fired district plants.

The difference between these options may well be the maximum allowed differential of 4 EAc1 points.

I eagerly anticipate any other responses and the forthcoming DES Guide.  (Did I miss the public comment period?)

Paul Riemer

From: Seth P. Spangler [mailto:sspangle at rmf.com]
Sent: Wednesday, May 06, 2009 12:46 PM
To: Paul Riemer; bldg-sim at lists.onebuilding.org
Subject: RE: [Bldg-sim] District Thermal Energy in LEED

In the Step 2 model for the baseline, you DON'T use the same district energy system used in the proposed.  Instead, you use on-site boilers of the type specified in ASHRAE 90.1 Tables G3.1.1A and Tables G3.1.1B.

Interestingly enough, this is a contradiction from what is stated in paragraph G3.1.1.1 of 90.1, but USGBC has clarified their intention in soon to be released updates of the DES Guide.

Seth Spangler, LEED(r) AP
Design Engineer

RMF Engineering, Inc
Ph: (843) 971-9639 ext:1497
Fax: (843) 971-9641
sspangle at rmf.com
From: bldg-sim-bounces at lists.onebuilding.org [mailto:bldg-sim-bounces at lists.onebuilding.org] On Behalf Of Paul Riemer
Sent: Tuesday, May 05, 2009 4:12 PM
To: bldg-sim at lists.onebuilding.org; bldg-rate at lists.onebuilding.org
Subject: [Bldg-sim] District Thermal Energy in LEED

Fellow Modelers,
I would greatly appreciate any answers and comments on formulating a submission and/or CIR.

I am working on a LEED project which is heated by steam from a coal fired plant and is subject to the USGBC's District Thermal Energy document https://www.usgbc.org/ShowFile.aspx?DocumentID=4176.
Should the baseline hot water boiler plant in the Step 2 analysis be:
A) a coal fired boiler with the proposed boiler efficiency since 90.1 does not address coal fired boilers,
B) a natural draft coal fired hot water boiler with an assumed code efficiency since 90.1 does not address coal fired boilers,
C) a natural draft gas fired hot water boiler with the code efficiency referenced in 90.1, or
D) something else?

Remember the metric is energy cost savings.

If you reread it, replacing the word 'coal' with 'trash', does your answer change?

Thank you,

Paul Riemer

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