Method: Chiller coefficient of performance is: COP = Cooling Capacity ÷ Electrical Input Power where both values are expressed in kW. Refrigeration tons are converted using: 1 TR ≈ 3.51685 kW of cooling Chiller efficiency in kW/TR is: kW/TR = Electrical Input Power ÷ Refrigeration Tons EER is calculated from COP using: EER ≈ COP × 3.412 where EER is expressed in BTU/h per watt. If operating hours are entered: Energy Consumption = Input Power × Operating Hours and: Electricity Cost = Energy Consumption × Electricity Tariff This calculator evaluates instantaneous or average operating efficiency from the entered cooling output and electrical input. Chiller efficiency varies with load, chilled-water temperature, condenser-water or outdoor conditions, fouling, controls and auxiliary equipment. For plant-level efficiency, include relevant pumps, cooling-tower fans and other auxiliaries in the electrical input if the objective is to assess the complete chilled-water system rather than the chiller alone.