Air Conditioner

BEE, EER, and ISEER Star Ratings in Appliances

When you get appliances, or buy them, you usually see various energy ratings. These ratings usually tell you about the energy efficiency of the said appliance.

These ratings, usually called EER, ISEER, are given by BEE, India.

ISEER EER BEE star ratings guide

BEE, stands for Bureau of Energy Efficiency, India.

So, let’s take a closer look at these terms.

Table of Content

What is BEE? What is its purpose?

Before moving ahead and discussing about EER and ISEER, let’s take a look at the agency which proposed them- BEE. In the year 2001, came Energy Conservation Act2001 for the purpose of conserving energy. This act called for a bureau to be set up called Bureau of Energy Efficiency.

So, Bureau of Energy Efficiency or BEE, was set up in the year 2002. It was set up as an autonomous government agency of the Government of India, under the Ministry of Power. Government then proposed for certain appliances to have BEE ratings, starting January 2010.

The purpose of BEE is to develop policies and strategies emphasizing self-regulation. Its prime objective is to reduce the intensity of energy in the economy.

In a nutshell, BEE, India, is an autonomous government agency which focuses on energy efficient appliances and ways.

Well, now that we know the agency behind energy ratings, let’s take a look at the energy ratings themselves.

What is EER?

BEE star ratings in AC

Before understanding EER we need to understand what efficiency is. Efficiency can be calculated by dividing the output by input. Let’s consider this. There are two appliances- A and B. They both are given same amount of input. With same given inputs, if A gives higher output than B, then A is more efficient than B.

EER, otherwise known as Energy Efficiency Ratio is the measure of the relative efficiency of an electrical appliance. We get this ratio when we put the output per hour to the energy consumed in an hour. If we’re talking about an Air Conditioner, then this value will be BTU per hour to Watt.

Fret not, we’ll discuss these terms in more details ahead in this article.

What is ISEER?

There’s another term that’s usually used synonymously, or goes used hand in hand with EER. This is ISEER. However, before going to ISEER, we need to understand what is SEER. SEER is an Energy Efficiency Ratio for seasonal appliances.

What it means you ask?

Well, when you use seasonal appliances such as AC, they don’t always consume the same amount of energy. This depends on their surroundings’ temperature.

An Air Conditioner will consume more energy to bring the room to the desired temperature if the room’s temperature is comparatively higher.

The bottom-line is that these appliances consume different amounts of energy in different seasons and weather patterns. An EER won’t be applicable for these kind of situations, hence we have SEER- Seasonal Energy Efficiency Ratio.

As seasons and climate patterns vary from one country to another, different countries have their own Seasonal Energy Efficiency Ratio.

ISEER is otherwise called Indian Seasonal Energy Efficiency Ratio. It is the Indian standard of SEER. It was introduced in the year 2016 and brought into action from 1st January 2018.

When ISEER was introduced, the secretary of BEE-India at that time, said that this new rating method would bring in India, higher energy efficiency and lower electricity consumption.

Let’s understand it a little more clearly with the help of an AC.

Apparently, they have more to them than just plain, old cooling.

Energy Ratings in an AC

Before going into detail about EER and ISEER ratings in Air Conditioners, we need to learn few other important terms first.

ISEER ratings

Also ReadBest inverter Air Conditioners in India

What is Tonnage?

Tonnage of an Air Conditioner does not refer to its weight. However, it refers to its cooling capacity. This capacity is measured in Tons. Higher the tonnage, higher the capacity.

0.75 TonsSmall Bedroom
1.00 TonsSmall office cabin/ small conference room/ normal sized bedroom
1.50 TonsSmall office cabin/ small conference room/ normal sized bedroom
2.00 Tonslarger workspaces

One Ton is equal to the amount of heat (288,000BTU) that is required to melt one ton of Ice in a period of 24hours. We do not need ACs to produce heat though. So, how does the whole tonnage thing work out for ACs?

Inverter AC vs Non inverter ac

Well, when we talk about AC capacity in Tons, what we mean is not the amount of heat we require to melt the ice, but the amount of heat that the AC can remove.

A one ton AC would be about 12000BTU/ Hr and a two ton AC would be 24000BTU/Hr.

We have seen the term BTU a couple of times in this article so far. So, what is BTU, you ask.

Let’s see.

What is BTU?

When you see 12000BTU/Hr, you realise that BTU must be some kind of unit. You’re right. It is an unit.

BTU stands for British Thermal Unit. It is a standard for measuring heat. As the name suggests, BTU is a British system. Higher the BTU, higher will be the cooling capacity.

Wikipedia describes BTU as the “amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit (1°F)”.

According to Wikipedia,

1BTU = 0.2931 Watt/hr

1Watt = 3.412142 BTU/hr

What is CoP?

We need to understand one more term about Air Conditioners. CoP is an abbreviation for

Coefficient of Performance.

Coefficient of Performance is usually associated with heat pumps and Air Conditioners. CoP of an AC would be the ratio of the hear removed per watt to the power consumed per watt. EER and CoP can be related in this equation-

star ratings for air conditioners

EER = CoP × 3.412

Now, let’s see how efficiency in Air Conditioners is measured. How do EER and ISEER work for AC.

What is EER in ACs?

EER or Energy Efficiency Ratio, in ACs is the output divided by the input. In an AC, the output is the amount of heat removed and the input is the power given. So, for an AC, EER would be the amount of heat removed divided by the energy it consumes. In other words, it is BTU/hr ÷ Watt.

As we have discussed in this article, an efficient Air Conditioner would be one which has a higher output. A higher output would give a higher EER rating. It goes without saying, an Air Conditioner with higher EER rating would be more efficient and would consume less power.

What is ISEER in ACs?

ISEER or Indian Seasonal Energy Efficiency Ratio was introduced by BEE, India. ISEER was put in effect from 1st January 2018 for cooling devices like ACs and Refrigerators. Each star rating value corresponds to a range of ISEER value. Let’s look at the star ratings

ISEER ratings

and their corresponding ISEER value. Following is a table showcasing the star ratings (both old and new) and their corresponding ISEER value-

Star Ratings (2015-17)
Star Ratings (2018)
ISEER value.
1--2.70 - 2.89
2--2.90 – 3.09
313.10 – 3.29
423.30 – 3.49
533.50 – 3.99
--44.00 – 4.49

After 2018, ACs with ISEER value lower than 3.10 were not to be manufactured. Also, the value range 4.00 and above were not available for fixed-speed ACs.

So, ACs with ratings more than 4.00 were, and still are, all Inverter ACs.

Inverter AC vs Non inverter ac

The higher the ISEER value of an AC, the lesser energy it consumes. Inverter ACs is the most energy efficient models of ACs there are in the market. They consume less energy and are lighter on our pockets.


Being energy efficient is not only lighter on your pocket, it is also lighter on the earth. By choosing appliances that consume less power, you’re helping not only yourself but you are also helping conserve energy.

Energy conservation and efficiency is very important in our life. In this article we discussed, in brief, about BEE, EER, COP, ISEER of an AC and in general. Hope this piece helped you.

Let us know what you think of this article and what other topics would you like to read on. Stay safe and happy.


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