Tonnage, COP, EER, SEER, ISEER and Star Rating For Air Conditioners

What is TR or Tonnage of Refrigeration:

Tonnage of Refrigeration is the unit of measurement of cooling of a refrigeration or Air conditioning system. It is defined as the rate of heat transfer that results in the freezing (or melting) of 1 ton (2,000 lb; 907 kg) of pure ice at 0 °C (32 °F) in 24 hours.

 A ton of ice melting over 24 hr provides a ton of refrigeration each hour. 2,000 lbs. of ice at 144 BTUs per pound = 288,000 BTUs 288,000 ÷ 24 hrs. = 12,000 BTUs per hour, or 1 ton of refrigeration. (3024 Kcal/Hr or 3.5 Kw)

What is COP ?

 COP stands for Coefficient of performance; COP is a measure of efficiency of a refrigeration system or heat pump and it is defined as

 (useful heating or cooling) / Work done.

COP is unit less and higher the COP simply means better the efficiency of refrigeration system.

What is EER?

EER Stands for Energy efficiency ratio and generally used in air conditioning system., EER is the amount of heat removed by air conditioning system divided by the power consumed. The Accepted norm of EER is at 27 Deg C of inside and 35 Deg C of outside room temperature at 50% RH.

EER =  (BTU/hr)/ Watt

Higher the EER ratio means higher the efficiency of refrigeration system.

Relationship between EER and COP

EER is having different unit while COP is having same unit, hence relation between EER and COP is as below :-

EER = 3.41214 × COP

Note: Nowadays people have started using EER with same units of refrigeration and power and define EER as (W/W), in such cases EER and COP has no difference.

What is SEER ?

Efficiency of air conditioner is now rated as SEER, SEER stands for seasonal efficiency ratio and is defined output of air conditioning system in typical cooling season divided by energy input during same period.

Higher SEER rating means higher energy efficiency of air conditioning system. As SEER is defined based on cooling season it differs based on geography. In India ISEER is used to define efficiency of air conditioning system.


Indian Season energy efficiency ratio is the output of air conditioning system corresponding to Indian season divided by power consumption during same period.

Being India a vast country and various seasonal differences region wise, BEE has formed reference outdoor temperature guideline for Indian region as a whole for measuring output of the air conditioning.

Star Rating:

To promote awareness among common consumers Bureau of Energy efficiency (BEE) has labelled appliances in rating of 1 to 5, where 5 star represents highest energy efficient appliance and 1 star represents lowest, The star rating helps consumers to take informed decision about the product purchase.

For More Detail on ISEER and Star rating. Please click here

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