ISEER vs BEE vs EER Star Rating of an Air Conditioner

When you go to buy a new air conditioner, it is not surprising to get confused when the salesman tells you about “star rating.”

You might be boggled with words like ISEER, EER or BEE star labels that air conditioners come with.

Does this star rating actually indicate efficiency of the air conditioner? Or is it yet another technical jargon?

In this article, we will review air conditioner star ratings – ISEER, EER and BEE – and how these help determine performance and quality of your heating and cooling system.

What is Air Conditioner Star Rating?

A “star rating” shows the energy efficiency of the electrical appliance. More stars indicate better efficiency and greater savings on your electricity bills.

ISEER, EER and BEE Star Ratings of Air Conditioner

When buying an air conditioner (or any electrical equipment for that matter), it is important to compare the star ratings of different models to best determine how efficient it is in energy savings.

This is an important parameter to consider because a higher star rating would mean long-term savings on energy bills and the best value for your money.

There are different types of star ratings that you will come across when buying electrical equipment – ISEER, EER and BEE.

How do they differ in indicating energy efficiency of the air conditioner? Which one should you give more importance to when comparing different air conditioner models?

Let’s go into more details of understanding different star ratings.

What is ISEER?

ISEER, or the Indian Seasonal Energy Efficiency Ratio, is the ratio indicating the total amount of heat that the AC can remove from the indoor air when operating in active mood to the total amount of energy consumed by it annually during that same period.

ISEER is a new method of energy efficiency star rating and works on the following concepts:

  • Cooling Seasonal Total Load (CSTL): It indicates the total amount of heat that the air conditioner can remove from the indoor air when it operates in the active mode.
  • Cooling Seasonal Energy Consumption (CSEC): It implies the total amount of electricity or power the air conditioner consumes when it functions in the active mode for effective cooling.

Therefore, ISEER = CSTL / CSEC.

According to the Bureau of Energy Efficiency (BEE), the average total annual energy consumption is 1600 hours.

Thus, a higher ISEER rating implies a more energy-efficient air conditioner that can help you save on your energy bills in the long run.

Bu purchasing an air conditioner with higher ISEER rating, you can get the following key benefits:

  • Reduced electricity consumption and lower energy bills
  • Eliminates moisture from the air and aids in improved humidity control
  • Eco-friendly with enhanced sustainability

What is EER?

EER, or Energy Efficiency Rating, is defined as the heat that the air conditioner removes per hour divided by the power it consumes. That means if the air conditioner has a higher EER, it indicates higher efficiency.

Typical norm of EER is – the 35 degrees temperature outside the room, 27 degrees temperature inside the room, and humidity of 50%.

The formula of EER = BTU / hour / Watt

Wondering what is BTU?

According to Wikipedia, BTU is the “amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit.” That means 3,412 BTU = 1 Kw/hr.

EER is determined by the electronic appliance’s BTU for cooling capacity and the Wattage for power inputs.

To make it simpler for you to understand, here is an example. If your air conditioner is of 10,000 BTU and consumes 1,200 watts, its star rating will be = 10,000 BTU / 1,200 watts, i.e. 8.3.

Just like ISEER, a higher EER indicates increased energy efficiency and higher cooling capacity of your air condition while ensuring improved savings.

Discussed here are the advantages of buying an air conditioner with higher EER:

  • Air conditioners with higher EER are costlier but ensure more savings in the long run. It is because they are more energy efficient and consumes less power, allowing you to save more in your energy bills

Which is Better – ISEER or EER?

India witnesses diverse temperatures across the country and so are the seasonal changes. Such, the EER standard of measure performance and energy efficiency of an air conditioner is not ideal.

The usage of air conditioners in India vary from season to season and from one region to another depending on the outdoor temperatures there.

For this reason, the Bureau of Energy Efficiency (BEE) introduced a new form of EER standard, known as ISEER. It is made mandatory from 2018 onwards.

In the new standard, the earlier EER brackets were revised and holds different for Split and Window air conditioners.

The following chart shows the ISEER rating plan for split air conditioners (as defined by BEE) effective from 1st January 2020 to 31st December 2021 with 1-star upgradation for 2 years:

Star LevelISEER Band
1 Star3.30 – 3.49
2 Star3.50 – 3.99
3 Star4.0 – 4.49
4 Star4.5 – 4.99
5 Star≥ 5.0

For unitary air conditioners, below is the proposed ISEER star rating plan valid from 1st January 2020 to 31st December 2024 with 1-star upgradation for 5 years:

Star LevelISEER (Min)
1 Star2.70 – 2.89
2 Star2.90 – 3.09
3 Star3.10 – 3.29
4 Star3.30 – 3.49
5 Star≥ 3.50

What is BEE Star Rating?

BEE, or the Bureau of Energy Efficiency, is operated by the Government of India that introduced the concept of energy efficiency and conservation for electrical appliances in India.

A BEE star rating implies the capacity of the air conditioner in terms of its volume, storage volume, and energy consumption per unit.

Similar to ISEER and EER, a higher BEE star rating would indicate more energy efficiency.

That means an air conditioner with 5-star BEE rating will consume less power than a 3-star A.C, helping you save more in electricity costs. Initially, it will cost higher than a 3-star A.C. but it ensures increased value and more savings year-on-year.

To calculate BEE star rating of an air conditioner, different factors are taken into consideration like annual power use, adjusted storage volume, constant multiplier and fixed allowance.

It is determined by the value of ISEER and EER. A higher value indicates more BEE star rating which means more energy savings and less electricity bills every year.

The core objective of BEE is to spread awareness for energy consumption through using electrical appliances that are energy efficient, Eco-friendly and aid in long-term sustainability.

Difference Between ISEER, EER and BEE?

Essentially, there are no significant differences between ISEER, EER and BEE star rating of an air conditioner or any electrical appliance.

BEE has introduced the concepts of ISEER and EER to measure the A.C’s cooling capacity against its level of power consumption.

All the three star ratings help determine the device’s level of energy efficiency and how much you can save in the long term.

EER RatingsISEER Ratings
Approved InternationallyApproved by Indian Govt
Rated for Non-Inverter ACsRated for Inverter ACs
No Seasonal EffectDepends on Seasons
Constant Value around the WorldChanges w.r.t Temperature
Less AccurateMore Accurate

How to Read the Star Rating of an Air Conditioner?

If you would look into a BEE star label, there is much more than star ratings in it. These include:

  • Star rating: More stars mean more savings in electricity bills. When you are comparing air conditioners of similar models, consider buying one with higher star rating. It will be more expensive initially but helps save higher over the year.     
  • Efficiency parameter: It indicates electricity consumption of the device in terms of units per year. Lower “Units Per Year” would indicate more savings.
  • Label period: It shows the time period for which the star rating standard is applicable. It is revised by BEE from time to time. Make sure you check the label period to ensure the star rating is updated.
  • Brand & model: The BEE star rating label also shows the type of appliance, brand, model, and year of manufacturing.
  • Technical parameters: It shows technical details related to the type of appliance.

Some star labels also mention the relevant BEE star rating plan.  

Final Words

Buying an air conditioner is a hefty investment and you would expect the best value for your money.

While you must take key features, the right tonnage and performance of the air conditioner into consideration, it is also crucial to check the rating levels.

A higher star rating does indicate more energy savings but you have to understand that there is not much difference in EER of 3.29 in a 3-star A.C. and 3.30 in a 4-star air conditioner.

So if you choose to buy the latter thinking it has a higher star rating, it would be wrong. It will only increase your costs significantly with no much difference in energy savings and costs.

Therefore, along with the ratings, it is also important to evaluate the EER or SEER plan before your buy.

We hope the above article equips you with ample information to question your HVAC dealer and have the best deal. Understanding these technical jargons will help you buy the right air conditioner that is high-performance, energy efficient as well as pocket-friendly.

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