How to Convert Full Load Efficiency to COP

Heating and ventilation engineers prefer water to air when it comes to cooling large buildings. Pound for pound, water can carry four times as much heat energy as air, and occupies only about one-thousandth of the volume. Water-based chillers can operate with much smaller pipes than air-transfer units, and are generally more efficient. The full-load efficiency of a chiller, expressed in kilowatts per cooling ton, is a common measure of its effectiveness, although many designers also specify the coefficient of performance, or COP.

Calculator

Instructions

- 1
  Note the full-load efficiency of the chiller that you need to convert. This should be given in kilowatts per cooling ton and is measured during final factory testing. This data is included with the documentation provided by the manufacturer. If you do not have the factory test report, contact the manufacturer. Typical efficiency values are generally available online.
- 2
  Divide 12,000, the number of British thermal units per hour in one cooling ton, by the full-load efficiency and note the answer. For example, if the efficiency is 0.8 kilowatts per cooling ton, the answer is 15,000.
- 3
  Divide the answer by 3,412, the number of British thermal units per hour in one kilowatt. Record the result, which is full load efficiency of the chiller converted to the COP. For example, if the answer is 15,000, the COP is 4.4.

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