ARI 560-2000 Integrated Part Load Value (IPLV) is a single number measure of part load cooling performance based on a weighted average of common building types, operating hours and average U.S.A. weather data.

Part load performance is often expressed as Coefficient of Performance (COP):

COP = Net Output / Net Input

IPLV =0.01A+0.42B+0.45C+0.12D

Where A, B, C and D are part load COP's at the following conditions:

Since the minimum gas input to the chiller-heater is 30%, the corresponding cooling capacity at 70.0°F cooling water inlet is 33.6%. The equivalent COP at 25% cooling capacity (Point D) is calculated from this conditionto account for cycling.