Refrigeration & COP
Every efficiency metric in refrigeration is the same number wearing a different hat — COP, EER and kW/ton all describe one ratio. What actually sets the ceiling is the temperature lift: the gap between evaporating and condensing. Drop the condensing temperature a few degrees and the whole machine gets cheaper to run, which is why condenser fouling costs so much.
Carnot uses the refrigerant’s saturation temperatures, not the air or water temperatures either side — the approach across each heat exchanger is part of what a real machine loses. A well-designed chiller runs roughly 40–60% of Carnot; well under that usually means excessive lift, fouling, or a badly matched compressor. Rated efficiency figures such as IPLV and SEER are seasonal averages and are not comparable to a single-point COP.
Design-stage estimates. A real project needs a full load calculation to the ASHRAE/CIBSE procedure, and ventilation rates are code-mandated — check the standard and jurisdiction that apply to your building. A helper, not a substitute for engineering judgment.