Refrigeration Efficiency – Terms and Conversion Factors

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COP = EER / 3.413
COP = 12 / (KW/TON) / 3.413
EER = COP X 3.413
EER = 12 / (KW/TON)
KW/TON = 12 / EER
KW/TON = 12 / (COP X 3.413)

 

Definitions:

COP or Coefficient of Performance. In a refrigeration system it is the dimensionless ratio of the heat removed to the energy required to remove it. In a heat pump it is the dimensionless ratio of heat produced to the energy required to produce it. For example a geothermal heat pump operating at a COP of 3.5 moves 3.5 units of heat for each unit of energy consumed.

EER or Energy Efficiency Ratio. The unit-less measure of the efficiency of a refrigeration system operating at standard conditions.

SEER or Seasonal Energy Efficiency Ratio. It is the EER averaged over varying conditions during the season. The government uses SEER to predict the seasonal energy use for appliances. There is no direct conversion to EER.

KW/TON is the electrical power used by a refrigeration system in kilowatts divided by the tons of refrigeration produced under standard conditions. One ton of refrigeration equals 12,000 Btu/hr.

Examples:

If a chiller’s efficiency is rated at .95 KW/ton, the COP is 3.7 and the EER is 12.6.

A geothermal heat pump operating at COPheating 3.5 provides 3.5 units of heat for each unit of energy consumed (e.g. 1 kWh consumed would provide 3.5 kWh of output heat). The output heat comes from both the heat source and 1 kWh of input energy, so the heat-source is cooled by 2.5 kWh, not 3.5 kWh.