Inverter AC vs normal AC
April 21, 2017What is Inverter Technology AC vs normal AC
Air Conditioners are a pain point for most people in our country who are concerned about their electricity bills. The moment an air conditioner
is added to the list of appliances used in a household, the electricity
bills increase significantly. Although it is difficult to significantly
reduce the “big” impact of an air conditioner on your electricity
bills, but still some of it can be managed by choosing the right
technology, doing the right installation/maintenance/operation and by
doing the right insulation of the room where the air conditioner is used
(more details in our articles listed at the end of this article).
When it comes to technology, there were
not many available till sometime back. When BEE actively started
analyzing and labeling the air conditioners, we got some good one in
form of 5 star air conditioners. The latest and the most efficient
technology that is available in market today is the Inverter Technology
for air conditioners. Inverter technology is designed in such a way that
it can save 30-50% of electricity (units consumed) over a regular air
conditioner. And since 2016, BEE has started give star ratings to
inverter technology ACs as well. However, let’s look at what is inverter
technology and how is it different from a non inverter BEE 5 star rated
ACs.
How does an air conditioner work?
For most people, air conditioner just
throws cool air at the temperature one sets it at. But does it really
work that way? In fact air conditioner during cooling process, takes the
indoor air, cools it by passing it through evaporator and throws it
back in the room. It is quite opposite to how our good old air coolers
used to work. Air coolers used to take outside air, cool it with water
and throw it in. But air conditioners just work on internal air. Along
with evaporator air conditioner also has a compressor that compresses
the gas (refrigerant) in the AC to cool it that in turn cools the
incoming internal air from the room.
In a regular air conditioner:
The compressor is either off or on. When
it is on, it works at full capacity and consumes full electricity it is
designed to consume. When the thermostat reaches the temperature level
set in the AC, the compressor stops and the fan (in AC) continues to
operate. When the thermostat senses that the temperature has increased,
the compressor starts again.
What is Inverter Air Conditioner?
The inverter technology works like an
accelerator in a car. When compressor needs more power, it gives it more
power. When it needs less power, it gives less power. With this
technology, the compressor is always on, but draws less power or more
power depending on the temperature of the incoming air and the level set
in the thermostat. The speed and power of the compressor is adjusted
appropriately. This technology was developed in Japan and is being used
there successfully for air conditioners and refrigerators. This
technology is currently available only in split air conditioners.
What is benefit of Inverter Technology?
Every air conditioner is designed for a
maximum peak load. So a 1.5ton AC is designed for a certain size of room
and 1 ton for a different size. But not all rooms are of same size. A
regular air conditioner of 1.5ton capacity will always run at peak power
requirement when the compressor is running. An air conditioner with
inverter technology will run continuously but will draw only that much
power that is required to keep the temperature stable at the level
desired. So it kind of automatically adjusts its capacity based on the
requirement of the room it is cooling. Thus drawing much less power and
consuming lesser units of electricity.
Although air conditioner with Inverter
Technology adjusts its capacity based on the room requirement, it is
very important to install a right sized air conditioner in a room.
Please make sure that you evaluate the room and air conditioner capacity
before you make a purchase. Keep watching for this space as we are in
process of creating a comparator for electricity savings in various air
conditioners.
What’s the difference between Inverter Technology AC and BEE 5 star non inverter AC:
Inverter technology air conditioners adjust their speed/tonnage depending on heat load of a room. Whereas regular air conditioners do not.
Every room has a different heat load, even if they are of the same size. The heat load depends on various factors as we have listed on our article: Things that impact electricity consumption in air conditioners. To give you an analogy, every human being is different; even then the waist sizes of most trousers available in the market are fixed (leaving the ones with elastic). Inverter Technology AC is just like a trouser with an elastic waist that can adjust to the size. The other benefit is that even if the waist size increases or decreases, the trouser with elastic will adjust accordingly. Regular Air Conditioners are fixed size.
Based on the data on power consumption by BEE, Inverter ACs of BEE 3 star ratings are about 7% more energy efficient than BEE 5 star rated non inverter ACs.
The heat load in a room does not remain constant and it varies from seasons, varies based on number of people, varies between day and night, varies based on climate profiles of your location. To take the same analogy we mentioned above, the waist size increases or decreases with the amount of food one eats or the amount of exercise one does. So as a trouser with elastic waist can work well, an air conditioner with inverter tech can work well.
Power Consumption of Inverter and non inverter air conditioners.
Based on data from BEE in 2017, below is the representative (median) sample of power consumption of Air Conditioners of various tonnage and star ratings:
What is inverter AC how it works
These days you hear so many advertisements talking about inverter AC, inverter fridges and even inverter Microwave ovens. So what is this "inverter" they are all talking about? What is an inverter AC, how does an inverter AC work? What are the advantages of inverter AC technology? We aim to answer all these questions hereAdvantages of Inverter AC vs normal AC
The best type of AC to buy in India is an inverter AC, which not only saves electric power cost, but is more silent and comfortable with steady continuous cooling.A normal AC first over cools the room and cuts off the compressor till the room again gets warm, then it will restart. This constant starting and stopping of normal AC compressor makes the room too cold for a short while and then it becomes too warm. This is does not lead to a comfortable sleep. Also with the AC compressor running at high speeds when it is on, and with the constant restart of the AC compressor, a normal AC consumes a lot of current making a normal AC very inefficient and costly to use.
An inverter AC on the other hand controls the temperature of the room
by running the compressor at different speeds, at very slow speed when
the room is at the right temperature and speeds up if the temperature
starts going up. Thus a room cooled by an inverter AC stays at a
constant comfortable temperature enabling a very good sleep.
Compare
inverter AC vs normal AC, an inverter AC uses 40% less electric power
and you get a much better sleep with constant cool temperature. The
inverter AC is very silent and lasts much longer than normal AC, because
the inverter AC runs at slower speeds and there is no wear and tear of
the compressor stopping and starting constantly.
How does inverter AC work
In an inverter AC, the 50 cycles per second or 50Hz alternating current in our power supply is first converted into a Direct Current DC and then it is reconverted into an alternating current where the frequency is infinitely variable, from say 10 cycles per second or HZ to say 100 cycles per second. This variable frequency enables the main compressor motor of the AC to turn at different speeds. With the fixed 50Hz AC of our electric supply, the compressor motor of normal air conditioner can only turn at one speed, but with a variable frequency, the compressor motor of the AC can run at different speeds, from very low to very high speeds. There are many advantages of the AC compressor to be run at different speeds as explained below.The problem with the fixed 50Hz power supply is that it will turn electric motors only at only a fixed speed depending on the number of poles. Then you may ask, but we can have our fans running at different speeds without an inverter? Yes true, but the fan speed control is limited and is achieved by the use of changing the number of poles or by changing the voltage which can only have a very limited speed control and is not very efficient.
Since the speed of any electric motor depends on the frequency of the voltage applied to it, so to control the speed of an electric motor, the most efficient way is to control the frequency of the power supply voltage. To achieve this, the AC power supply to our houses has to be first converted into DC and this DC power converted back to AC voltage with the ability to infinitely control the frequency of the AC voltage. The device that converts DC voltage to AC voltage is known as an inverter.
Which AC is better inverter AC or 5 star normal AC
A 5 star normal AC is the most efficient normal AC, but it cannot be as efficient as an inverter AC, because the inverter AC works on a totally different principle. Also inverter ACs have no star rating as yet in India.The regular AC compressor has only one speed and the cooling is controlled by offing the AC compressor when a set cold temperature has been reached and then restarting the AC compressor when the room heats up and reaches a set temperature. For example, if you set the thermostat in the regular AC to cool the room to 22 degrees, then the AC
compressor starts when the room temperature is 24 degrees and stops when the room has cooled to 20 degrees. This is the cycle that repeats itself throughout the period that the AC is on. This is a very inefficient way of the compressor working. The problems with this arrangement are as follows:
When a compressor is running at its full speed it is very inefficient. The relation between efficiency and speed is that efficiency varies inversely as the square of the speed. To put it simply, if the speed is double then the efficiency reduces by a factor of the square of the speed, that is efficiency reduces by 4 times. So, the slower the compressor runs, the more efficient it is.
Start up current in any motor is very high. When a normal AC is on, the compressor starts and stops several times, minutes apart. This start stop cycle consumes a lot of power and is very inefficient.
The temperature in the room is not a constant comfortable level. It is varying between a minimum and maximum temperature of several degrees apart, and the room is constantly changing from uncomfortably cold to uncomfortably hot, with the set comfort temperature zone in the middle of these uncomfortable temperature range.
The graph below shows the room temperature of a normal AC compared to inverter AC
An inverter compressor in AC solves all the disadvantages of the
normal AC and saves more than 40% on electricity bills as claimed by
some of the manufacturers. Apart from this the inverter AC is very
silent compared to a normal AC and the compressor lasts much longer,
because it is never stressed.
When an inverter AC is put on, the compressor starts slowly and picks up speed gradually and reaches a higher speed than a normal AC for a short period to cool the room faster than a normal AC. Once the set temperature of say 22 degrees C is reached, the compressor slows down and has just enough speed to maintain the set temperature of the room. The compressor never stops while the AC is on; it just runs very slowly cooling the room just enough to maintain the set temperature. The variance in temperature in the room will be in decimals, in our example of 22 degrees it may go down to 21.9 and up to 22.1 degrees, which is negligible.
Thus the monthly power bill for a normal AC, assuming Electricity cost at Rs.5- per unit, will Rs.1,500- per month compared to Rs.900- for a 1 ton inverter AC. Therefore the saving in electricity cost of a 1 ton inverter AC for a month is Rs.600-, and Rs.7200- per year.
In the above example let us say that the 1 ton inverter AC costs Rs.10,000- more than the normal 1 ton AC, then with the monthly electric bill saving of Rs.600 per month, you will have paid off this extra money for the inverter AC in a matter of about one and half years. If you use the inverter AC for 5 years, then you will have saved more money with the inverter AC than the cost of the AC itself.
Apart from the cost savings in the running costs of an inverter AC, you will have a much more silent AC. The room temperature with an inverter AC will be always comfortable without the room becoming too cold for some time and then becoming too warm like with a normal AC.
One important consideration when buying an inverter AC is the Star Rating of inverter ACs. We have pages explaining what star rating of inverter ACs mean and also how much more monthly electric bill you can save by buying a 5 star inverter AC instead of a 3 star inverter AC.
Why inverter AC better than normal AC
An inverter compressor in AC solves all the disadvantages of the
normal AC and saves more than 40% on electricity bills as claimed by
some of the manufacturers. Apart from this the inverter AC is very
silent compared to a normal AC and the compressor lasts much longer,
because it is never stressed.When an inverter AC is put on, the compressor starts slowly and picks up speed gradually and reaches a higher speed than a normal AC for a short period to cool the room faster than a normal AC. Once the set temperature of say 22 degrees C is reached, the compressor slows down and has just enough speed to maintain the set temperature of the room. The compressor never stops while the AC is on; it just runs very slowly cooling the room just enough to maintain the set temperature. The variance in temperature in the room will be in decimals, in our example of 22 degrees it may go down to 21.9 and up to 22.1 degrees, which is negligible.
Inverter AC saves Electricity with lower monthly power bill
A normal one ton AC uses on an average about 1.25 units of electricity every running hour. This of course will vary depending on many factors like outside temperature, insulation factor of the room, etc., but 1.25 units of electricity is about the average. The 1 ton inverter AC power consumption per hour would be about 40% less than that of a one ton normal AC. That means the power consumption of a 1 ton inverter AC will be about 0.75 units of electricity. Assuming 8 hours of operation per day, that will be 10 units of electricity per day for normal AC and only 6 units per day for a 1 ton inverter AC.Thus the monthly power bill for a normal AC, assuming Electricity cost at Rs.5- per unit, will Rs.1,500- per month compared to Rs.900- for a 1 ton inverter AC. Therefore the saving in electricity cost of a 1 ton inverter AC for a month is Rs.600-, and Rs.7200- per year.
In the above example let us say that the 1 ton inverter AC costs Rs.10,000- more than the normal 1 ton AC, then with the monthly electric bill saving of Rs.600 per month, you will have paid off this extra money for the inverter AC in a matter of about one and half years. If you use the inverter AC for 5 years, then you will have saved more money with the inverter AC than the cost of the AC itself.
Apart from the cost savings in the running costs of an inverter AC, you will have a much more silent AC. The room temperature with an inverter AC will be always comfortable without the room becoming too cold for some time and then becoming too warm like with a normal AC.
Best 1 ton and 1.5 ton inverter split AC in India
We have a dedicated page showing all available models of inverter air conditioners available in India and this is the clickable link to it: Best inverter split AC available in India.One important consideration when buying an inverter AC is the Star Rating of inverter ACs. We have pages explaining what star rating of inverter ACs mean and also how much more monthly electric bill you can save by buying a 5 star inverter AC instead of a 3 star inverter AC.
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