Hi,everyone

Recently, I was working on a LEED project,And the reviewer gave below comments:

The MEPC Water-Side HVAC tab indicates that the Baseline Case has been modeled with the two-water cooled centrifugal chillers with each chiller cooling efficiency - kW per ton of 0.634 (full load), which appears to be inappropriate. Note that the Baseline Case water side equipment (i.e. chillers, pumps, etc.) type, size and related controls such as COP, secondary pump control, etc., must be determined based on the whole-building capacity. Based on the base building information provided, it is likely that the Baseline Case should be modeled with two water-cooled centrifugal chillers per ASHRAE 90.1-2010 Table G3.1.3.7 with each chiller cooling efficiency kW per ton of 0.576 (full load) and 0.549 (part load; if following path A).

Update the Baseline Case energy model and ensure that the Baseline Case chiller type and associated controls are modeled following the requirements of ASHRAE 90.1-2010 Appendix G (based on the base building peak load).

He(She) said LEED baseline chiller cop shoulde be based on building peak load,rather than single chiller capacity.For example,two chillers were modeled in my baseline case,and the capacity for each chiller is 160tons,and I use the capacity of 160tons to determine the COP, kW per ton of 0.634.And according to comments, I should determined the COP based on 320 tons,that is kW per ton of 0.576.

Which is right?

Thank you!

Yongqing