[Equest-users] modeling district plant projects per ASHRAE and LEED

Jim Weiner collaborative.jim at gmail.com
Thu May 15 08:38:15 PDT 2008

Hi eQUEST world,

Does this sound about right?

where our case is a large-scale DHC (District Heating/Cooling plant) which
provides steam and chilled water to each individual building within the
district and we have a LEED modeling effort...

We are modeling a 17 story office building in the district.

We have two issues:

*District Plant: *The building does not have it's own plant, but shares
plant with other buildings. This could be modeled by creating a "virtual"
plant within the building and plugging in a virtual rate for the actual cost
of energy from the district plant (you may not have to create a complicated
rate schedule if this is the case and the district plant sells energy
without a lot of complicated ratchets or off/on peak pricing). The annual
cost of energy would typically be lower because of the efficiency of
producing all the energy for a lot of buildings in one plant designed for a
lot of diversity.

*Combined Heat & Power (CHP):* The energy drawn for the building from the
offsite plant creates waste heat that the offsite plant can convert
efficiently into energy that is sold to others. This allows us to give a
credit to our project associated with the sale of by-product energy (in
LEED, associated only with the process load of our building only as I
understand things). This credit would be allocated proportionally to our
building's process energy use and reduces the annual cost of energy for our

The project needs to show compliance with prescriptive & performance
requirements of ASHRAE 90.1 independently of the district plant efficiency
or CHP credit in order to achieve the LEED prerequisite and credits.

Thanks for any comments/guidance/suggestions on approach!

James Weiner, AIA, Senior LEED Faculty
Collaborative Project Consulting
721 Rochedale Way
Los Angeles, CA 90049
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