[Equest-users] Chiller COP in baseline building

[Min-Hwan Yang]

Sam,

I would input 6.1 COP and specified as rated-condition.

Min-Hwan Yang, CEM, LEED AP
Mechanical Engineer | yangm at kjww.com

200 West Jackson Boulevard, Suite 1200 | Chicago, Illinois 60606
312-294-0501 | Direct: 312-356-3750 | Fax: 312-294-0003
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Building Design + Construction, March 2008

Everyone,
I am having an issue with determining the baseline chiller COP for a large lab building. The proposed design system is two 1600 ton centrifugal machines with 42F CHWT with 12F delta T, 85 ECWT, and 2.5gpm/ton condenser flow rate. Both units are rated at 5.72 COP which is above the minimum efficiency of 5.60 per Table 6.8.1J.  

In the baseline, there are 4- 800 ton centrifugal machines and per Appendix G3.1.3.8, the design supply CHWT should be 44F with a 12F delta T. So the question that arises is: what is the efficiency of the baseline machines?  If you use standard rating conditions of 44F CHWT,
85 ECWT, and 3.0 gpm/ton condenser flow rate, the minimum COP should be 6.1. If you use the design conditions for the building, it is 5.60.

6.1 versus 5.6 in lab building of >400,000 sq.ft. is a huge difference and could mean the difference between meeting minimum energy cost savings for EA credit 1.

Any thoughts, help, or experience is greatly appreciated.

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