What are Inverter ACs? And Are The Energy Saving Claims Right? [Updated]

Summers are upon us and most regions across Pakistan will be facing blistering heat for the next few months. With weather predictions of another heat wave striking the country, the season will only get more hostile. The only defence against such a weather are Air Conditioners, so we have decided to publish a series of guides on the matter.

This is the first one amongst the extensive series of guides that will be published here at ProPakistani. First up, DC Inverter AC’s.

DC Inverter ACs are all the rage these days. All major appliance manufacturers are claiming to have some new technology which can reduce electricity costs by 60 to 75 percent and still offer a better consumer experience.

Every day, we see some advertisements on these new types of ACs, but it’s hard to believe that such adverts could be true. Of course, how could there have been such a technology, yet we didn’t see or hear something about this a few years ago?

In this post we answer all your questions and inform you whether these huge claims from AC OEMs are close to the truth or not.

How do ACs work?

To understand DC Inverter ACs, we first need to understand how they work. Air conditioners use a refrigerant (a gas which exists in low pressure but turns liquid as the pressure increases), which is compressed and liquefied by the compressor. It is then cooled down in the condenser and later allowed to expand (become a gas) in the evaporator, albeit in a controlled manner. Those who have studied physics, would know that this expansion causes a cooling effect which, in turn, causing the condenser to become warm.

The same principle is used in refrigerators, they move the heat from the inside to the outside. When an AC is in cooling mode, the heat from the room is removed and pushed towards the outdoor unit of the split AC.

Image Source: Domain Appliances

If the AC has the ability to heat, it can reverse the process, the energy is absorbed from the outside while heating the room. In most cases, the reverse process, i.e. heating mode, consumes less power than the cooling mode because the compression energy is added to the overall heating cycle.

The remaining two important components of an AC are its motored fans. The outdoor fan chucks the air out of the condenser to the outside. However, the indoor unit makes use of the blower and louvers/fins to dissipate the cool air (or hot air if the AC is in heating mode) to the room.

What is a DC Inverter in ACs? (Technical Info)

A DC inverter converts AC current to DC current. It then uses a modulation technique (called Pulse Width Modulation) in another inverter to produce AC current based on the desired frequency and voltage. The variable frequency AC drives the brushless motor or induction motor. The speed of the motor is proportional to frequency of the new AC voltage. Thanks to this, the compressor can now run at multiple speeds.

*AC in the above paragraph means alternating current and not an air conditioner.

What’s So Different About a DC Inverter AC?

An air conditioner with DC inverter technology has the ability to control its cooling (or heat) transfer rate by changing the output from its compressor. The rate can be modified depending on the requirements of the room. To put it more simply, the AC uses electricity depending on the environment’s requirements.

inverter vs non inverter

The compressor in a common AC runs at full 100 percent all the time. When it is not needed it shuts off. So a common AC uses start/stop cycles to control the temperature.

When using a DC Inverter in an air conditioner, it uses a processor to check the surrounding temperature and adjusts the speed (power input) of the compressor based on it. It can provide different levels of cooling or heating. So the DC Inverter AC regulates its output capacity to uniformly control the temperature of the room.

How Does it Save Electricity?

Now we come to main question. Inverter ACs do save more energy and are more economical while still being environment friendly.

A conventional AC starts multiple times and always runs at peak capacity. This means that every time it starts it needs extra electricity to jump start its stationary motors and compressor, i.e. torque current. Without being too technical, you can think of it this way, it needs more power when it starts and it starts too many times. It also runs at full capacity each time requiring a lot of current.

Image Source: Slideshare

In comparison, a DC Inverter AC never turns off its compressor or motors. It reduces the electricity it needs and constantly keeps cooling (or heating) the room. When it does start the first time, a DC Inverter AC starts off slowly so it doesn’t require a massive torque current. Inverter ACs can start at low voltages as well thanks to the inversion mechanism. By running in a low power consumption state, DC Inverter ACs save a lot of electricity.

DC Inverter ACs aren’t as effective when running at full capacity, however, when they are running at partial capacity, which is how ACs are normally used, they can save a lot of energy.

What Are The Different Types of DC Inverter ACs

Some manufacturers claim they have 3-DC Inverter ACs, All DC Inverter ACs, 4-D Inverter ACs, etc, while others simply claim to have Inverter ACs. They also claim to have varying savings percentages from 60 percent to 75 percent.

The reason behind that is, some manufacturers employ older technologies and only upgrade their compressors to DC inverters. Others also convert the indoor and outdoor fan motors hence, completely upgrading all motors to DC inverters.

Those, which claim to save about 50 or 60 percent in electricity bills and simply state DC Inverter (or only Inverter) ACs, are using the inverter tech for the compressor only. 3-DC Inverter or 4-D Inverter systems, sometimes referred to as All DC Inverter, upgrade other motors or major electrical components as well. This means more savings as more electrical components get the ability to vary their speeds.

In short, a number besides the “D” or “DC” mean the number of components using the inverter technology.

Are the Electricity Bill Savings Correct?

As with all advertisements, the claims made by most manufacturers are based on optimum conditions and usage. If you have a 1-DC Inverter AC, it will save you around 40-50 percent in electricity bills under normal usage. 3-DC and 4-DC Inverter ACs can achieve over 60 percent in savings. You probably won’t get 75 percent in savings under normal usage and extreme heat in Pakistan. However, if your AC has the heating-mode, it will cause more cost savings compared to the cooling mode.

Normal conditions mean that the user does not set temperatures to extremes. If the temperature is set to extremely low (for cooling) or extremely high (for heating) then you cannot expect such huge savings. However, even at extremes, DC Inverter ACs beat the conventional ACs.

Final Words

Inverter technology isn’t new. Other countries have had these products for years. In most countries, conventional ACs have been phased out completely. Pakistani market only got the tech in recent years. And the credit for that goes to a new entrant in the Pakistani market, which was the first one to launch these DC Inverter ACs in Pakistan. Now that they are here, the prices for normal ACs have dropped rapidly.

As far as energy consumption is concerned, savings are always welcome. Not only do these ACs help save money, their use is good for the environment. The DC inverter technology will soon start being used in other products as well, so keep your eye out for that as well.

Have something to say or want to know more about this? Drop an email at [email protected] or find Aadil Shadman on Twitter (@ashadman25) or Facebook(fb.com/AadilShadman).

He is the Editor-in-Chief at ProPakistani. Reach out at aadil.s[at]propakistani.pk

  • Too Much Information These Days on ProPakistani :)
    Yesterday the AliBaba One and now this.. All Hail Aadil Bhai

  • Tell me best Ac available in market which consumes less electricity which can reduce electricity bill. I am not good in technical stuff.

    • It is a series of posts. So we will try and answer your question in complete detail later after some research. Since each user has their own set of requirements, we’ll try to make it easy to understand which AC suits you better.

  • DC Inverter AC will be able to save back only if they are able to run continuously on some solar power system or UPS backup , If these are running in same 1,2 hour loadshedding schedule we have here in Pak , you can kiss goodbye to saving altogether . bye the time AC reaches the desired temp say 25c Boom power off , AC off and it will start again t full power when power resumes . Manufacturers intentionally leaving out this important info.

        • Wrong. There is 2.5 Hours x 3 times in 24 hours. in DHA Areas. 2 Hours x 3 times in 24 hours in Shah Faisal Colony.
          But There are also many areas where no loadshudding like Gulshan-e-Hadeed (Normal Area) and All Army Areas.

      • :D Karachi bht bara ha Bhai, Zara Ghoom to lo Karachi phr btana Loadshedding ha k ni :D

    • You are partially correct. You see you will still get more savings if you use the AC when you get the electricity and there might still be ways you can optimise your AC usage to get the electricity savings.

    • I guess besides loadshedding making DC Inverter less power saving. Initial electricity load on starting of DC Inverter AC (i.e. torque) is low and doesn’t fluctuate the lights (on startup). This is another DC Inverter advantage.

    • Even with load shedding like we do have in our country, inverter based ACs will save energy. The total amount of energy saved will definitely be affected but that doesn’t mean that it won’t save. It still will save you significant amount of money.

    • As the literature says inverter AC has no full power or low power instead it runs at continuous power after a fraction of time. Normal A/c starts (at full power) and stops 5 times in an hour while inverter A/c starts only once (at full power) then it maintains its power consumption on lower side.

  • I think these ACs, if they can work with Solar Energy, can be a great thing. Direct Current from solar panels can reduce a lot in terms of electricity bills.

  • It is great to see ProPakistani touching topics not related to telecom. I want to see ProPakistani to cover all things about Pakistan and technology, keep it going.

  • Since ,Last month ,I was decided that to buy Inverter Ac but actually not able to decide that are these advertisement true or not.Now,I actually know that the real story behind that. Very Useful article.Thanks man

    • There’s more info coming on this topic. We didn’t want to flood our viewers with very long articles. Soon, you will get even more info on ACs.

  • Great article, right when its needed. I am in this exact situation (to switch or remain with old acs). For me the only concern is load shedding, with load shedding the temperature of the room would increase and inverters would have to work at peak consumption (I am not entirely sure but this would potentially drop the savings to an extent).

  • bhai propakistani zubaida apa hi ban gaya hai ab to.har aik cheez mn tang arana start hogaya hai.paki web enviornment ka zubaida apa.why not discuss about women dresses,health, kids health,property rates,lottery numbers,installments plans for cars,insurance schemes,schools and all shit

  • I have recently purchased Kenwood Inverter and it really saves a lot of energy if I use it for 8 hours continuously on 26 degrees. my 1.5 ton runs on 2.5 Amp as compared to 8A which non inverter AC consumes.

    • Have you observed an actual drop in your electricity bill? I assume you can mention make/model as well. But readers be ware, savings vary case to case. For instance, dont expect much difference in scorching heat of Multan.
      In my opinion, a no-risk solution is still insulation of roof and advisably walls.

      • The number of AC operational hours have been almost doubled without increase in the total bill. That means almost 50% saving.

    • We’ll cover the question raised by Hightower in a post a few weeks later. He’s partially correct but you still get the savings no matter what.

  • Wow Wow .. i was actually looking for this kinda info about inverter ac n also planning to buy one.. thanks man !!!

  • Very productive article. Please keep things simple to comprehend and to benefit the majority. Keep posting such articles. We will be waiting for more like this one.

  • Waiting for the next article and plz share it as early as possible because hard hot weather is started so plz tell which dc air conditioner is best which continously run on ups or solar

  • Conventional 1.5 ton AC runs on 13-14A. And 1ton required 6.5A as measured by me with Ampere meter.

    I still doubt an AC can save electricity that much, as procedure for removing heat from the room is same. However, technology has changed a bit (introduction of variable speed). Any person with close observation can guide here much.

    Like mentioning,

    1. Room size
    2. Sealing of the room/walls, sun effect on the ceiling
    3. AC size
    4. How many people inside the room
    5. In how many minutes it drops down the temp by 1 degree C and current consumption
    6. Then record performance every hour and current consumption

    Finally check how much hour is was operated and what it consumed in kWh. This will give a perfect rating.

    Being an Engineer, I can’t believe that it can save 40 to 60% electricity. Never

    • It would be nice if someone can give real statistics by comparing usage for a month of so. A KWH Meter would be helpful. I am sure it will be cost affective where the AC switches on and off often, but where it doesn’t, I am not sure there will be 50% savings. I tried to search google for any such article, but couldn’t find anything. One point that is not mentioned anywhere, is that when you convert AC into DC, there is loss of some power, then you convert DC back to AC, some more loss. So, not sure how it compares to the savings.

      • This topic belongs to the advance electronics department and as a researcher in advance electronics i assure you that this could be happened if you could increase the firing angle of the thyristor which reduces the duty cycle of the motor which means that these thyristor switches on and off in nano seconds. In other words these switches make it happen to keep the motor running just for 20% duration of a second.

        • At the moment, we are trying to evaluate local Inverter ACs, and compare them to non-inverter ACs.

    • My electricity meter turns 0.5 unit per hour with Inverter AC as compared to 2.5 units with non-inverter AC. This is my own experience, however, it is based on 8 hours continuous usage.

      • That is good, what is the Room Temperature set to, and what is outside temperature? Also, both ACs are of same capacity (1 or 1.5 Ton)?

        • The room temperature is set to 26 and outside temperature varies between day and night, i think it is mostly between 31- 33 during day time. And yes, both the ACs are 1.5 ton i.e 18000 btu.

          • Impressive, lets see if someone can test it when the difference is > 10 degrees, like in Lahore. If I run my A/C now, which is Dawlence 1 Ton Split, it runs for 20 minutes in cycles during 60 minutes, so I am sure if I switch to Inverter based, it is going to save me money. In May/April, that cycle changes, and it is about 45 minutes or longer Running Cycle during one hour, and that would be a real test for me.

  • “And the credit for that goes to the new European manufacturer which was the first to launch these DC Inverter ACs in Pakistan.”
    Can you tell us which brand is this just for our knowledge? Thanks!

  • Informative article. Looking forward to more such posts.

    Please share which one is the European Manufacturer?

  • Folks, can someone convert conventional AC (split unit) to DC inverter by modifying conventional compressor to DC compressor and fan etc.. is it possible ?

  • propakistani is trying to say what a dukandar always says about inverter ac.
    inverter does not safe electricity just because it converts ac to dc and thus there is loss in the form of heat. the reason it is able to safe electricity is due to compressor cycle and ability to run internal/compressor fan motor and optimal speed to distribute cold/hot air evenly.

  • Very well researched article. It should be noted, however, that being a new technology, there are some risks to being first adopters. Especially if you buy one of these from a not-so-well-reputed brand.

    • Thanks. The tech isn’t new, its just late in Pakistan. Conventional ACs have been nearly phased out in a lot of countries. Besides, 2016 would be the second year for these ACs if I am not wrong. The point about Brands is definitely correct.

  • I consider myself too dumb to understand such technicalities but u proof me wrong.
    Thank you very informative!!

  • Can you explain in single line that if I buy an (AC) inverter AC, will it save electricity and perform equal to a normal AC when I face load-shedding after each hour, few of my friends are saying it is a waste of money if I am facing this kind of load-shedding and I should go with a normal one, others are saying to buy inverter AC, what is your take?

  • Inverter ACs are of Low Quality you would have to forget the quality while using Local Inverter ACs. Secondly these inverter ACs are designed for low heat areas i.e 40 Degree Centigrade for the outer units. They fail to cool in hot summers when temperature goes beyond 40 in majority areas of Pakistan. They have slow cooling cycle means the amount of cooling you get from conventional AC is 4 times higher in Inverter One and other problem due to their slow cooling cycle and loadshedding they fail to cool the space. At last very important point our local Technicians are unaware to repair and maintain this technology. Ultimately this technology is for Europe not for Pakistan. If you spend low money you would have to sacrifice the luxury you expect. ACs are luxury in Pakistan due to high cost of Electricity and conventional split ACs are best to serve this luxury. May be some of the technical geeks dont agree with me.

  • I have installed inspire plus inverter 1.5 ton dawalance,its price is suitable ,on 24 c & on 17 c uses 3.5 amps cooling is awsome,we do not rank it no.1 because its pakistan made,if we are not to permote who else would ,secondly imported brands while using same technology as pakistani costs more, are we brand conscious? or non-promoter of pakistani brands?

  • Salam. Sir m ne apks article parha. Bhot si mufeed malomat mili. Thanx. Sir mjhe dc invertor lena hai. N me qta me rehta hon. Yahan chaman border se kaffi kum price me ac mil jate hain. Mjhe ye pochna hai k konsa 1 ton dc invertor bahir ka best hai jo bill efficient ho. Plz guide me.

  • Yesterday i installed Kenwood KDC-1804S 1.5ton 75% saving model, from yeaterday nihht 1am till now (loadshedding) i use 15h and used 21units .. Is it a Ok usage and power saving? AC runs on 26c all the time

  • Does the peak consumption of the non inverter model is same as the inverter one?
    This is confusing me. We have here – in Iraq – a brand named TOSOT. They’ve two kinds of 1 Ton, one is an inverter and the other is a non inverter. The inverter’s peak amperage is 3.7 A. However, the non inverter one has a peak Amperage of 6.1 A. Why is there such a difference? It only means that the inverter one does not have the same cooling capacity as the non inverter. The temperature here in summer reaches 50C or more, and the AC works nearly all day. I’ve a 20 Sqm room, and I am confused which one to buy, as I am afraid that the inverter AC won’t cool the room as the non inverter one. Please Advise me!

  • I have installed Kenwood 1.5ton eco, a true dc converter, they claim 75% saving which I observed was 65% and its true, for first trial I make it on for 6 hours from 11.00pm night to 5.00am by setting 26celceius,my room size is 14×17,top floor 3 sides open, set auto fan , and auto off through timer, in my meter reading it only drops 3.6 units average in night.

    That was really motivational for me and now the same eco model in 1 ton I installed in my another room. It drops 2.7 units in night by same settings as above

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