Our modern lifestyle is highly attached to electrical accessories. We need many home appliances like AC, refrigerators, microwave ovens, Washing Machine etc. Whenever you’re shopping for appliances, you will notice star rating stickers on the appliances. These are called BEE star labels( Buereu of energy efficiency) and they show how much electricity the appliance consumes in a year. These home appliances have star ratings. Higher star ratings have higher  efficiency.  

What is star ratings?  


A star rating system shows the energy efficiency of an electrical appliance. The higher the number of stars of the product, the more efficient it is. The star rating system was devised by the Bureau of Energy Efficiency (BEE) India. It has a range of 1 to 5 stars.

Using star ratings is one of the easiest way to determine and compare energy efficiency of home appliances we need. 

We will talk about different types of star ratings like EER, ISEER and you will get to know why these ratings are important when you will buy air conditioners.  

ISEER (Indian Seasonal Energy Efficiency Ratio):

Indian Seasonal Energy Efficiency Ratio (ISEER) is ratio of the total annual amount of heat that the air conditioner can remove from the indoor air when operated for cooling in active mode to the total annual amount of energy consumed by the air conditioner during the same period. 

Calculation of ISEER: 

How is ISEER calculated?

Star ratings is the simplest component when it comes to compare different AC models. 

ISEER rating is the total cooling load (amount of heat removed) to the total amount of energy that  consumes the air conditioner. Which means, ISEER = Cooling seasonal total load (CSTL) / Cooling seasonal energy consumption (CSEC). It is the new system of value calculation.  

EER (Energy Efficiency Ratio): 

Energy Efficiency Ratio (EER) measure of the relative efficiency of a cooling or heating appliance. It expressed as the ratio of output in British thermal units or Btus, per hour to the energy consumed in watts.

Calculation of EER


Energy Efficiency Ratio  generally given to the fixed speed compressor (non-inverter) Air conditioners. EER of an AC is defined as

EER = Amount of heat removed in an hour ÷ Power consumed in the same hour

How ISEER is different from EER?  

EER was the previous system of calculating the value of star ratings. 

Since the temperatures across India vary and there is extreme changes through the seasons, the EER standards method of calculating performance was not ideal enough. Air conditioners consume a lot of energy, resulting in high electricity bills. For this, BEE defined a new seasonal EER rating standard called ISEER in India.

Importance of EER and ISEER:

It is needed for significant energy savings. Low energy consumption translates to lower electricity bill. Lower utility bills mean more money-savings. Air conditioners with a high EER or ISEER are also known to have more effeciency in terms of cooling performance due to better technology, design, and components.

How is ISEER different?

The ISEER (Indian Seasonal Energy Efficient Ratio) rating standard was made mandatory from 2018. On the newly introduced ISEER rating standard, the existing EER star ratings brackets were revised. Also, keep in mind that ratings are different for Window and Split air conditioners. Given below are BEE defined, ISEER ratings valid from 1st January 2018 to 31st December 2019.

ISEER ratings for Window ACs

(Fixed and Variable speed )

ISEER ratings for Split ACs

(Fixed and Variable speed )

Star level



Star level



1 Star2.502.691 Star3.103.29
2 Star2.703.892 Star3.303.49
3 Star2.903.093 Star3.503.99
4 Star3.103.294 Star4.004.49
5 Star3.305 Star4.50

Remember that it’s not fair to compare the star ratings of a split air conditioner with a window air conditioner. For example, a 4 star window air conditioner will not have the same efficiency as a 4 star split air conditioner. Most manufacturers are reducing their Window ACs line-ups and focusing more on Split ACs, many of which are inverter based. The manner in which they function leads to better energy efficiency compared to non-inverter models.

BEE (Bureau of Energy Efficiency) star rating:

The Concept of BEE star rating is simple.

The ac’s are rated on a scale of 5 for their energy efficiency. Higher the rating more energy efficient it is which means it will consume lesser electricity. Star ratings start with 1 which is the lowest means the least efficient and goes up to 5 which is the highest means the most efficient. 

Meaning of BEE star ratings : 

The more  star rating of an AC, the less energy it will consume, and you will save more electricity bills.

So it will be easy to understand that a 4-star inverter AC will save more energy than a 3-star inverter AC. So always try to purchase a high BEE star rating AC like which have 4 stars or 5 stars. We also know that a 5-star inverter AC is expensive more than a 3-star inverter AC, but the 5 star AC will save huge money on electricity every year. So effectively, a better eco-friendly investment will be a 5 star AC rather than a 3 star AC.

Calculation of BEE: 

A formula using annual energy use, constant multiplier, adjusted storage volume and constant fixed allowance is used to calculate the star rating for a particular air conditioner. BEE is calculated by the value of EER or ISEER. Higher EER or ISEER value refers to  more BEE star rating, and it directly refers to more electricity savings with less electricity bill.

Objective of BEE star ratings : 

BEE has been rolling star rating for all the air conditioner brands since 2006. Not only air conditioners, but the government has also made the star ratings mandatory for several large appliances brands to mention their BEE star rating for their product since Jan 2010. The main purpose is to spread awareness among consumers to understand energy consumption better as well as they will get know which component is more effective.  

Final talk: 

If the usage of air conditioner is high, you must go for a high energy efficient product. Air conditioners can consume up to 1.5 units per hour of usage and it can be brought down to as low as 0.5 unit per hour. 

You should always pay attention to the BEE star rating of whatever type of air conditioner you are thinking of buying. Every air conditioner has a BEE star rating sticker along with the product details. Better the BEE star rating means lower will be energy consumption and bigger savings.

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