BEE Label of Air Conditioners: Tonnage, Energy Rating and ISEER Explained

Most of the people get a bit intimidated seeing the jargon associated with an air conditioner. 

Unfortunately, these are terms that you can’t ignore. Understanding them is quite necessary to buy an air conditioner that perfectly suits your needs without going overboard on budget. 

So here we explain in simple words the meaning and implication of the common terms you are likely to come across in your AC buying journey.

Tonnage Energy Rating ISEER


The first aspect that you would have to decide on is what tonnage AC to choose. 

I must confess, when I was a child, I used to think, ton referred to AC’s weight ( Yeah, I know…) But later I realized my folly. 

The tonnage you see on an AC specification actually refers to the cooling capacity of the AC. Technically, a ton refers to the heat required to melt 1 ton of ice in 24 hours. This amounts to 288,000 Btu ( British Thermal Unit) in 24 hours or 1200 BTU in an hour. So, if an AC has 2 ton capacity, it will be able to melt 2 ton ice block in a day. 

Practically speaking, a 0.8 ton AC would be ideal for a 100 Sq. Ft space. For up to 150 Sq.Ft, a 1 ton AC would suffice, while 1.5 ton AC would be enough for a 250 Sq. Ft space and 2 ton AC for 400 Sq. Ft space. 

However, other aspects like number of windows, tube lights, persons in a room and whether the ambient temperature crosses 45 degree, floor on which your home/office is located all affects the cooling capacity. You can take a look at Tonnage calculators from Carrier and BlueStar for a more accurate result.

Energy Rating

Bureau of Energy Efficiency provides energy rating for almost all heating and cooling appliances. This could very well be an important aspect to take care of while buying an air conditioner. Higher the energy rating, higher the power efficiency and lower your electricity bills.

ACs with 3 to 5 star energy rating are commonly found in the market. But do take care to look at the label period. A 5 star AC in the last label period might be just a 3 star AC in the latest label period. A good idea would be to check the latest energy rating from BEE website at

Now, the trade off is that, as expected, everything else being the same a 5 star AC costs more than a 3 star AC. Usually, you find at least 4 to 5K price difference. So, if you are someone who uses an AC for just a few hours every night during the summer, you could very well buy a 3 star AC instead of splurging on a 5 star AC.

Please do note that all 3 star ACs don’t have the same power consumption. It varies within a range and that is why you have further go in to details to compare and find out the AC with better energy efficiency.

Annual Energy Consumption of an AC

On the BEE label of an AC, you do find annual energy consumption of an AC. But let us not get deceived by it. This value is the energy consumed when the AC is run for 1600 hours at ideal conditions. 

So, if you use it just during the 4 summer months for 12 hours, then your annual consumption would be just 4 x 12 x 30= 1440 hours. But on the other hand, if you use it for your office for 10 hours for 20 days a month ( 10 x 20 x 12) that would be 2400 hours annually.

So, the best way to use this figure would be to find out the per hour energy consumption by dividing the value by 1600 and then calculate how it works out for your needs.

Also, obviously, when comparing two ACs of the same tonnage, lower annual power consumption, the better.


EER refers to Energy Efficient Ratio. It is simply the amount of heat removed per hour divided by power consumed by the AC.

That is,

EER= BTU/hr/ Watt

As you can see, the higher the EER, the better the AC is, because it cools better all the while consuming minimum energy.

ISEER ( Indian Seasonal Energy Efficiency Rating)

This value refers to the ratio of heat removed by the AC from the indoor air to the amount of energy consumed by the AC. This is calculated on an annual basis. 

Temperature ranging from 24 to 43 degree Celsius is considered to calculate the amount of heat removed. And the total hours of annual operation is taken as 1600 hours. 

Further the average number of hours of occurrence of each temperature is considered to find the bin hours and then the ISEER value is calculated.

Other features being the same, when considering two ACs that have the same energy rating, choose the one with higher the ISEER value as it means better cooling efficiency and lower energy consumption.

So, to wrap it up, while choosing an AC, first consider the tonnage, other features that you are looking for and energy rating. Among the ACs with same energy rating, choose the one with higher ISEER rating. Among brands, LG is definitely the front runner. Options like Daikin, Blue star etc are also quite good. Among the more budget friendly options, you could consider Voltas, Whirlpool, Godrej and Sanyo.

You can check out our article on Best Split ACs and Best Window ACs to view the picks vetted by experts.


Parvathy Pothan

Parvathy Pothan is the founder-editor of Smart Home Guide. She has been featured in All Recipes, The Hindustan Times, Mid-Day, The Print and other leading publications. She completed her graduation in Business Management from EHSAL European University College of Brussels. Following a brief stint at her family business dealing in home maintenance, furnishing fabrics and interior designing, she ventured out to start her own publishing business where she and her team strives to educate consumers and help them make an informed decision for buying home and kitchen appliances.

Read more posts by Parvathy Pothan


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