[Bldg-sim] District Thermal System
juliabeabout at yahoo.com
Wed Aug 6 07:05:57 PDT 2008
I think everyone is wrestling with the new rules trying to figure out how to apply them especially with respect to step 2. You can query USGBC directly (at no cost) at leedinfo at usgbc.org. I've found that the front line customer service people are not that familiar with the new rules yet either; but, they can elevate your question to the appropriate parties. It just may take a little longer than usual to get an answer. If your question is too project specific, they may tell you to send in a CIR instead.
Do you know the cost of your chilled water/hot water that the municipality is going to charge you? If so, I don't see the new Step 2 modeling requirements as a whole lot different from the old modeling rules. The NEW rules require a virtual chiller plant/boiler plant to be modeled that is reflective of the actual plant's efficiency. Under the OLD rules, if you knew the cost of the chilled water/hot water, that cost was supposedly, inherently, reflective of the plant's efficiency as long as it incorporated all production costs (i.e. chillers, cooling towers, pumps, boilers, as applicable per utility) and could be used directly in your proposed model. I would say this approach still holds true for the NEW Step 2 model. You may just need to do a little investigation with the utility and provide some back up data or a letter to LEED as a supporting documentation stating that all the relevant production costs are reflected in the cost
of chw/hw (assuming that's the case). If you wanted to dig a little deeper, you may be able to get (electrical and chw/hw water production) metering data from your utility and confirm/determine an actual cost from that. The NEW rules mention monitoring data as an allowable means of determining the virtual central plant's efficiency.....it seems like metered electrical input and production output would fit this description.
----- Original Message ----
From: May Xu <may.xu at hok.com>
To: Jeff Haberl <jeffhaberl at tees.tamus.edu>; bldg-sim at lists.onebuilding.org
Sent: Tuesday, August 5, 2008 10:19:55 PM
Subject: Re: [Bldg-sim] District Thermal System
Thanks, I found many useful information there, it is a very good
resource! However, I didn't get relative answers regarding my question,
which is about the simulation rule updated by USGBC recently about the
district thermal system. Could anyone give me any suggestions?
Thanks a lot!
From: Jeff Haberl [mailto:jeffhaberl at tees.tamus.edu]
Sent: Tuesday, August 05, 2008 11:36 AM
To: May Xu; bldg-sim at lists.onebuilding.org
Subject: RE: [Bldg-sim] District Thermal System
The Laboratory has spent quite a bit of time modeling the thermal plant
on the Texas A&M Campus with good success. Unfortunately, we ended up
using some rather complex, interacting loop models with chiller on/off,
staging algorithms, etc.
We have a number of papers and thesis on this at our web site
"www-esl.tamu.edu" look under publications.
8=! 8=) :=) 8=) ;=) 8=) 8=( 8=) :=') 8=) 8=) 8=?
Jeff S. Haberl, Ph.D.,
P.E.............................jhaberl at esl.tamu.edu
Department of Architecture.......................Lab Ph: 979-845-6065
Energy Systems Laboratory.......................FAX: 979-862-2457
Texas A&M University..............................77843-3581
College Station, Texas, USA.......................URL: www-esl.tamu.edu
8=/ 8=) :=) 8=) ;=) 8=) 8=() 8=) 8=? 8=) 8=) 8=)
From: bldg-sim-bounces at lists.onebuilding.org on behalf of May Xu
Sent: Mon 8/4/2008 4:53 AM
To: bldg-sim at lists.onebuilding.org
Subject: [Bldg-sim] District Thermal System
I'm now working on a project using Districted Heating System provided by
a municipal system. The municipal system is working for a very large
areas providing steam for about hundred buildings. And my building is
one of them.
According to the latest update issued by USGBC
(https://www.usgbc.org/ShowFile.aspx?DocumentID=4176), the modeling will
be implemented by two steps. My question is about Step-2 (Aggregate
Building/DES Scenario). In step-2, the energy source of Proposed
Building is virtual on-site chiller representing upstream DC system. The
document also issues "The DES central plant itself shall always be
modeled as a total, entire unit." My understanding is that it requires
to model the central plant with the full capacity that is able to
provide heating for all of buildings in whole district. However, if
doing so, the energy consumption of the proposed building may be quite
quite high, since it includes the energy consumption of the whole
heating plant!! But my building is only one of the 100 buildings that
are heated by the central plant. It is weird and I don't think it is
what USGBC asked for. Does anyone know what shall I do for the proposed
building in Step-2?
May Xu, LEED(r)AP
Project Engineer - Sustainable Design
Suite 3705A, Ciro` s Plaza,
388 Nan Jing West Road,
Shanghai, 200003, PRC
Tel: (86 21) 6334.6181 ext. 2230
Fax: (86 21) 6334.6182
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