[Equest-users] Chiller COP in baseline building

[Sam Mason]

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.

Sam

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Sam Mason
Atelier Ten