[Bldg-sim] Performance Rating Method of of Ashrae 90.1 (2004) Baseline Chiller COP

[Ho Tinkit]

Regarding to the Performance Rating Method of of Ashrae 90.1 (2004), there
is an issue of  determining baseline Chiller COP need to be clarified.

Regarding to the baseline HVAC system, the parameters need to be set
according to Appendix G of Ashrae 90.1 Standard.
According to table G3.1.1A and table G3.1.1B of App. G3.1.1, the baseline
HVAC system for a building with area larger than 150,000 sqft is specified
as variable air volume with reheat with centrifugal chiller >300tons,
whereas the equipment efficiencies should be modeled at the minimum
efficiency levels in accordance with section 6.4 of Ashrae 90.1 Standard.
Then referring to table 6.8.1 J of section 6.4 of Ashrae 90.1 Standard,
minimum efficiencies for centrifugal chiller COP(standard) should be 6.1.

However, What is the minimum efficiencies for the baseline design COP under
the following condition,
1) If the proposed HVAC design is design to work with leaving chilled water
at 42.8F and entering condenser water temperature of 85F,
2) If the proposed HVAC design is design to work with leaving chilled water
at 42.8F and entering condenser water temperature of 89.6F, and this chiller
is designed to be a ice storage system.

Should the baseline design be modeled at COP 6.1 or should the baseline COP
be estimated by the equations listed below the table 6.8.1 J?

Please advise.

Thanks you for any kindly helps.

Regards,

TK HO
Senior Assistant Engineer
Scott Wilson Ltd
Tel. no. (852) 2410 3847



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