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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256 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.

Guest
Vidit mehta
Today 12:50 am

Hi I have bought 1.5 tonsplit ac for a 250 sq ft room of Hitachi company but since installation my usage has been for night times only but now my normal electricity bill has gone up to 3000 which earlier use to be 800 rs. Kindly guide me with ideal mode for usage and temp. To be set so I can save on my bill amount. I live in mumbai. I noramly keep temp at 21 degrees and keep it on auto mode.

Guest
Siddharth
July 2, 2015

Hi BB team ,
I have a room of size = 12X21=252 sq. ft on first floor cieling is exposed to Sun. I was told to purchase a split Ac of 2 ton and not a window AC of 2 ton by a technician of AC. When I asked the technician of why not purchase a 2 ton window AC when it is lesser in price ,easy to install , Power Consumption is nearly Same and moreover the btu Cooling of both window n split is same.
He told that in 2 ton split AC the condensor coils are large and the gas Condensation is easily done in large coils so the cooling is very fine.
Whereas in a 2 ton Window AC the condensation Coils are small and the gas is not condensed easily so in 2 ton Window the Cooling fails.
Please give correct advice on whether to purchase a split unit or a Window unit of 2 ton ?

Guest
Sathish kumar
June 30, 2015

I am using Blue Start A/C 1.5 ton, 5 star. My room size is 14/14. I am using the ac at 30. Will it consume more power.

Guest
christopher Foo
June 28, 2015

How to maintain office room temperature at 24 degree celcius of 600 sq ft? How many hp aircon needed?

Guest
Kartik
June 18, 2015

Sir, i live in top floor in delhi. My landlords have given me an AC but have disabled the power save mode(obviously). The meter is also there. How do I minimize the meter reading? The meter runs faster than usain bolt. :|

Guest
Tapas Roy
June 15, 2015

I have purchase a 1.5 ton AC, make carrier. 3 star. My house size is 12’x 12′. I leave at west bengal. I have to run my ac for 4-5 hours per day (maximum) only for summer session. Is my decision right or otherwise. Please answer me.

Guest
ashutosh
June 14, 2015

Sir,I bought blue star 1 ton 5 star split ac…at starting it works fine but now when I turn off the ac by remote..a cracking sound come from the indoor unit like internal body is broking but when I turn off by main switch..its okkk.no sound coming…is there problem or not…and one more thing that left side of air wing not blow air properly….i have clean the filter but air not coming properly from the left side of the wing…what’s the problem

Guest
jraju
June 13, 2015

How to find that the compressor stopping stage, if one has set , a set degree temperature. I ask this question, because, the compressor is outside the room. Is there any indication light that will show, only fans are running.

Guest
jraju
June 15, 2015

There should be something indicating to this effect. OK researchers will have to think about it. I am having 2ton inverter ac. If i select 26 , and select sleepmode, how much units of current will it take. it has the cooling capacity of 3550watts and power consumption of 1080 watts/ How to calculate the unit of power consumption for this ac if one selects sleep mode in it.
i learnt that sleep mode reduces consumption of electricity. I am asking this , as i do not find any other topics that relate to this

Guest
jraju
June 12, 2015

How to maximize the ac benefit of voltas inverter ac. In which mode one use the 2 tonne ac. what is special about the word inverter in it

Guest
jraju
June 12, 2015

Could you allow downloading the tips video

 
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