[Bldg-sim] Water or air-cooled chillers in baseline models?

Michael Rosenberg Michael.Rosenberg at state.or.us
Thu Mar 20 09:08:58 PDT 2008


You are correct, all chillers modeled in the baseline building per Appendix G are water cooled. See G3.1.3.11 Heat Rejection (Systems 7 and 8), which states "The heat rejection device shall be an axial fan cooling tower with two speed fans...". 

Since this issue was confusing to others as well as your client, it was clarified in the 2007 version of Appendix G, and now specifically adds "Water-Cooled" to the chiller type in the table.


Michael Rosenberg
Oregon Department of Energy
625 Marion St. N.E.
Salem, OR 97301-3742
Phone : (503) 373-7809
Fax: (503) 373-7806

>>> "Jessica XP" <xupingjessica at gmail.com> 3/20/2008 8:33:44 AM >>>
Dear folks,

APP G3.1.3.7 specifies centrifugal chillers in baseline models where
conditioned area is greater than 22,296 m2. I always take them as
water-cooled chillers by default.

Today one of my clients challenged why air-cooled centrifugal chillers can't
be modeled in the baseline. His argument is that there is not any
"water-cooled" explicitly specified in G3.1.3.7, but there are air-cooled
centrifugal chillers available in the market.

I was attemping to convince him of my understanding by searching
ASHRAE 90.1and the associated user manual. But I failed to find any
evidence. I doubted
if I was wrong.

Is there anyone in this forum who can give me an answer? And if I am still
right, how can I convince my client who is hungry for points of EA cr1?

Tons of thanks in advance.


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