Electricity Saving Tips For Homes And Offices

Ideal Air Conditioner temperature for electricity savings

By on May 14, 2015

Buying an air conditioner once considered a sign of luxury, is now becoming quite common in India. Many urban homes are equipped with air conditioners in one or more rooms. But everyone who owns an air conditioner knows that it comes at the cost of increasing electricity bills. Although cooling does take a lot of electricity but taking effective steps can surely get it down. One of the main things that can help is maintaining the right temperature for the air conditioners.

Air Conditioner Temperature

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 coil 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.

How does the thermostat work?

If you set the thermostat at 18oC (64.5oF), does it mean that the air conditioner will cool the room faster than if set at 25o(77oF)? No. The thermostat just checks the temperature of the air inside the room and stops the compressor when the temperature reaches the desired level. This means that the compressor will work longer if the temperature is set to a lower level, i.e it will work more and use more electricity if temperature is set to 18oC (64.5oF) than if it is set to 25oC (77oF). This is because it will take less time for air to reach to 25oC (77oF) than 18oC (64.5oF) as the compressor is working with the same power or wattage.

What happens when the compressor stops?

The air conditioner just blows the fan when the compressor stops and thermostat reaches the desired temperature level. At this stage the electricity consumption is only for the fan which is running and not for the compressor. The compressor will start again when the thermostat detects that the temperature has increased again from the levels that are set. Compressor is the most electricity consuming component of an air conditioner.

What factors impacts electricity consumption of Air Conditioner?

There are 4 factors that influence the electricity load:

1) Indoor air temperature

2) Outdoor temperature

3) Thermal insulation of the room

4) Temperature setting of the air conditioner.

If the difference between temperature desired and indoor/outdoor temperature is huge, then the air conditioner will need lot more electricity to cool the indoor air to desired temperature as the compressor will run for longer duration. If the temperature is set at 18oC (64.5oF) and the outdoor temperature is 38oC (100oF) then the electricity required will be lot more than when thermostat temperature is 24oC (75oF) and outdoor temperature is 38oC (100oF). As per study by ACEEE (American Council of Energy Efficiency Economy), increase of each oC can save 3-5% of units consumed. This can considerably bring down the units consumed per month in the electricity bill.

What is the ideal temperature that should be set on thermostat?

Having said that, increase in temperature does not reduce the comfort level. In fact as per ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers), the ideal temperature for thermal comfort is between 23.5oC (74.3oF) and 25.5oC (78oF) in summers (depends on several factors as listed on wikipedia). Thus setting the temperature to 24oC (75.2oF) saves on electricity bill and provides good comfort. Using ceiling fans along with air conditioners can additionally help in increasing the thermostat temperature.Air Conditioner Temperature Infographic

Does “Quick Cool” option in Air Conditioners help?

Setting an air conditioner to quick cool sets it’s temperature to 18 or 16 oC (64.4oF or 60.8oF. This means that the compressor stops only when indoor temperature reaches this level. But while coming down from 35 or 40 oC (95oF or 104oF) it would have surely crossed 24oC (75.2oF) which is a comfortable temperature. So using “Quick Cool” option does not help because more electricity is used to get the temperature down to 18oC (64.5oF) whereas compressor would have stopped in between if the temperature was set to 24oC (75.2oF) thereby consuming less electricity.

How do old air conditioners without thermostat work? 

Old air conditioners without thermostat have high, medium and low cool options. As we learnt earlier that compressors of air conditioners work in binary mode (either they are on or off), an air conditioner without thermostat does not control air temperature. The high, medium and low options just changes the air conditioner fan speed. High means that air conditioner will throw more air and low means that the fan speed will be slow. The options do not change the temperature of the room, nor do they change the electricity consumption.

Here is a short video for tips to reduce power consumption of air conditioner in India

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191 Comments on "Ideal Air Conditioner temperature for electricity savings"

If you have any question or comment, please leave a message here. We try to reply to questions in the sequence they come in. We work from Monday-Friday 10AM-7PM. If we know the answer we try to reply to the question within 3 days.

May 25, 2015

Hi BB Team, I have purchased 1 ton Samsung Neo Series AR12JV5HBWKNNA Inverter AC, on which degree Temperature set by AC will save electricity more.
Please help. Or how to auto set thermostat at that level.
Thanks, Sachin ,Patna

May 23, 2015

hello team.
I am having a whirlpool 1.5 Ton 3 star AC since 2011. Those days it worked fine even in summers at temperatures above 42 deg C. But since last year in summers, whenever i used to turn on the AC arround 12pm it ran fine upto some time..then got tripped off and it went on. It tripped every 2-3 minutes after the compressor starts. However, the AC works fine during night time. Last year i got it checked by an engineer but still then the problem persisted to some extent. This year same thing is happening. I also have tried to cool down the condenser ( thinking it to be due to overheating of condenser at 42 deg C) by putting some cold water over the fins of condenser part, but still facing the same problem. The complaint regarding the matter has been registered but they are yet to attend it. PLEASE HELP..!!

May 24, 2015

Hi @tinu.. I am from chenni and have a 1.5ton LG AC system. It also has the same problem. It works very well at night, but during scortching sun it does not cool :)

May 22, 2015

sir my Voltas 1.5 tonne 3 star AC bought 1 month ago…tried to test…not cooling below 22 degree centigrade.ran for 3 ours still temp dint go below 22 degree :(

Jose Antonio Eguaras
May 20, 2015

what is wrong when you set the desired room temperature to 25 degress celcius at about 6.00 pm and after 8 hrs or at 2.00 am the room temperature on the remote is 26 degress and the compressor has NOt knocked off since ithe aircon was set on. The room seems to be colder than the 25 degrees at 2 am

May 19, 2015

Hello sir. …as you told earlier that lloyd ls18gri will consume 1.2 unit per hour in night but it is consuming 10 units for running 5 hrs at temp set at 26….room size is 15×13 it has no floors up …I m not running ceiling fan as it is giving hot air. ….is unit consumption is ok? ???? Or there is some problem

May 19, 2015

How much power will be consumed when we keep that ac in 28 degrees for the whole night?

May 17, 2015

My Samsung Aircons compressor doesn’t cuts off?is there a problem with condenser?

Dixit Arora
May 17, 2015

Hi team,

I bought the voltas 1 ton window a.c three days ago. After installation of unit I find that the adjacent wall vibrates too much. I call for engineer from voltas. He havent visit yet. I have run the a.c for whole last nite, it doesn’t cool to my expectation. Does it have problem with it compressor.

ram Mahto
May 16, 2015

I bought a split AC last year of capacity 1.5 ton. I have a doubt that this AC is not cooling on time and more time is being taken by ac to cool the room. The AC is set at 16, and it took 35 minutes to bring down the temperature from 34.7 to 25 degree celcious. Is it taking right time or is it taking more time…???

Thanks and Regards

May 15, 2015

I am using voltas 1.5 ton 5 star split ac. Want a clarity on one thing.if at all I am switching of the ac through the remote where as I am not switching off the main power will electricity consume or not !

May 21, 2015

Thank You.