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Why and How Can Inverter Technology help to save electricity?

I get this question frequently. Not just from ordinary people (laypeople) as well as from tech-savvy engineers and technocrats. A popular phrase will be “Just cutting off the cycle of on/off, will not lower your costs by 7-10 percent. The promises of 40% savings are just marketing hoopla.”. I was involved in a long conversation with a friend on the topic in the past, which inspired me to create this post. I hope this article will give people a better understanding of how technology like inverters can help conserve energy.

Furthermore, I was unable to find any other research paper or website and so on. Providing this information. Therefore, you won’t see any references in this article. We discuss related to Inverter Technology in detail. However, this post was written from my personal experiences and observations from the last 8-9 years of working on Bijli Bachao and studying the market.

In this article, we will mostly be using Air Conditioners as a reference appliance. But, the same principle applies to refrigerators too. However, I am unable to claim the same for washing machines due to the absence of market data on the same (and some sense). Three of these are the only items that I have seen using inverter technology used in India.

If you’re looking for information on the inverter technology, look it up on this page: What is Inverter AC, and how is it different from Non-Inverter AC?

Let’s take a look into Air Conditioners.

A lot of people call me and inquire: “What is better in 5- Star AC that will save more energy when compared to the 3 Star? or is 5 Star just marketing hype?”. 

• It uses an improved refrigerant which provides higher thermodynamic efficiency.

• They are increasing or enhancing the surface of heat exchanger (mostly condenser) areas to allow for better heating dissipation.

• Use better compressors inverter technology, etc.

One of the comments I heard from a man was that companies are producing five-star inverter ACs that have larger condensers. This is the reason they are more efficient when compared to non-inverter ACs with 3-star ratings. If they make non-inverter ACs with bigger condensers, they’ll save money. Significantly I agree that non-inverter ACs can’t be enhanced. However, this article is about arguing for the use of inverters, and the reason it is logical to invest in inverter technology and not as much in non-inverter technology. Let’s dive into some numbers and see how they compare to figures.

The Numbers are Compared

To help compare the numbers, I’ve taken the information from two models of Daikin which are a bit like each other. Both models are BEE 3 stars with identical ISEER numbers and technology. One model is a non-inverter and the other is an inverter. The reason I chose Daikin is that I believe they’re pretty great in terms of being transparent regarding numbers. The majority of Japanese brands offer a decent amount of data, however, Daikin is the most reliable for information that can be used to help you make a decision.

Let’s Dive into Some Calculations:

Our Scenario – Room 1

The current temperature in the room is, 16000 BTUs (at 40°C)

The room is heated at the desired temperature between 8000 BTUs (say roughly 20-21°C)

The room is heated by the flow of heat (through walls/humans, etc.) – 4000 BTUs/hr

Thus, after the extra 8000 BTUs is eliminated, in the steady-state the AC will need to take out 4000 BTUs/hr in order to maintain the temperature (or to maintain the temperature to 8000 BTUs).

An inverter Air Conditioner – BEE 3 starDaikin FTKL35

capacity of cooling for the AC 3350 Watts (or 11782 BTU/hr)

Energy Consumption for the AC 918 Watts

EER or ISEER = 3350/918 = 3.65

In the first hour, it will need to eliminate in the first hour 8000 BTUs plus around 2000 BTUs which are because of the temperature gradient that is created. Thus, roughly 10000 BTUs have to be eliminated within the first hour.

Time to run the same amount = 10000/11782 = 0.848 hours or 51 mins.

Thus, Power Consumption = 918 multiplied by 0.848 (779 Wh), or 0.779 units

Then it must eliminate 4000 BTUs/hr. Thus, each hour it will run for 4000/11782 = 0.3395 hours or 20 minutes

Power Consumption each hour equals 918 * 0.3395 is 311Wh, or 0.311 Units.

If the AC is running for 8 hours the power consumption would be 0.779 * 7 = 0.331 equals 2.96 units.

An inverter AC – Daikin FTKL35 (BEE 3 star)

Cooling Capacity Variation of the AC (Max) 3700 Watts, Min 1070 Watts (Max) 3700 Watts (or 12600 BTU/hr) and (Min) 1070 (or 3650 BTU/hr)

Power Consumption Variation of the AC The AC’s power consumption range is (Max) 1200 Watts, and (Min) 220 Watts.

If we assume that the change is linear and runs along straight lines. The relationship between power consumption can be described as

y (cooling capacity) = MX (power consumption) + c

then m = (3700 – 1070) / (1200 – 210) = 2.656

and C = 512.12

It is the same as non-inverter AC in the first hour, the AC must remove approximately, 10000 BTUs. In steady-state it will take away approximately 4000 BTUs/hour (or 1137 watts)

Assume that for the one hour, the speed of operation of your AC is at a level that averages at 10,000 BTU/hr (or 28,43 Watts).

By using the line formula The power consumption is

(2843 – 512.12)/2.656 = 877.59 watts

Thus, the consumption of units during the 1st hour equals 877.59 Watts or 0.87759 units. (which is higher than the AC that is not inverter-controlled’s 1st hour). If it linearly behaves.

Then, in the next 24 hours, it will need to eliminate 4000 BTUs/hr or 1137 Watts.

By using the same formula, the power consumption is:

(1137 1137 512.12)/2.656 = 235.27 Watts

Thus, the consumption of units after 1 hour = 235.27 wh, or 0.23527 units

Total Power Consumption in 8 hours = 0.87759 + 7 x 0.23527 = 2.5244

Total Savings

Non-inverter used 2.96 units in just 8 hours.

The inverter AC used up to 2.5244 units in just 8 hours.

Saves = 0.42552 units equals 15 percent of 2.96

Based on these calculations, simply changing the compressor to an equivalent inverter compressor, you can reduce energy consumption over a time lasting 8 hours.

Why does an inverter AC provide better efficiency for smaller tonnage?

With lower cooling capacities, the gas that is pumped out is lower. This means that less heat is dissipated by the condenser. The condenser stays cooler, and lesser pressure is put on the compressor. The compressor, therefore, draws less power and is efficient. The condenser is already big.

Important Observations based upon the calculations above

What sense can you get from the above calculations? You could use it to inform your decision-making process?

  • The inverter AC is ideal when they come with a large tonnage range, so they can meet the least cooling requirements in addition.
  • Undersized Inverter ACs are bad and won’t save you any energy. However, oversized inverter ACs can save you money with a large power cooling capability (or tonnes) range.
  • You will definitely save on energy by using the Inverter AC. The switch to turn it off or on doesn’t assist in reducing your energy consumption. It is better to maintain it at an appropriate temperature and make use of it for a long.

Does the ISEER Code Provide any Benefit to the Consumer?

The ISEER number or the annual energy consumption offered to you is designed to allow comparisons of ACs. It could be a helpful instrument when trying to make a purchasing decision. However, it is not applicable in actual life since the ISEER you get from your inverter AC could be quite different from what is described. It will be contingent upon the conditions under which an inverter AC is operating. For non-inverters inverters, the ISEER does not alter based on the running conditions. For an inverter AC with a large size that has a large cooling capacity, you could attain ISEER that is much greater than that stated and for smaller inverter ACs, the ISEER will be less. An inverter AC that has a greater cooling capacity can have the potential of offering higher ISEER than an inverter AC that has a smaller cooling capacity.

What Can We Do As Consumers?

The most crucial thing to do is solicit information. While there are a handful of manufacturers, the majority do not offer a lot of data to be able to compare. Sure, we have information from BEE which receives tests reports from manufacturers conducted in a NABL accredited laboratory, however, the data they provide is not sufficient. The calculation of ISEER is based on the power consumption of ACs inverters at 50% and 100 percent capacity. It does not take into consideration the capacity of the lowest level that the AC is able to run at or the power consumption that it consumes at the capacity.

 The nature of ACs that inverts is so complex that it’s difficult to conduct a typical apple-to-apple comparison without standardizing the calculation procedure. But, there’s more to it than typical comparisons that could provide additional information. Without getting into complicated calculations, it is best to examine ACs that have larger cooling capacities. You can ask for the information!


Inverter technology isn’t simply a buzzword. It’s great for ACs and refrigerators. Making the right decision and using it correctly is essential for your energy-saving endeavor.

DisclaimerThis study is solely based on data from the market and observations. Kishore Brother’s haven’t measured any appliances in order to accurately determine the amount of electricity consumed. This is based on the trust we place in manufacturers to ensure they are providing accurate information.

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