Last Updated on April 5th, 2021 by RefrigeratorPro Team
More than a third of the world’s population live in countries with average daily temperature higher than 25°C. However, yearly temperature varies considerably in every country. This is one of the reasons why most countries have their own SEER (seasonal energy efficiency ratio) to determine the energy efficiency of AC units. India has its own ISEER (India seasonal energy efficiency ratio) to determine star rating that indicates energy consumption of an AC.
However, power consumption of AC not only depends on its ratings but lot of factors such as outdoor temperature, indoor temperature, number of people in the room, insulation of the room and usage.
Table of Contents
Relationship Between AC Temperature & Energy Consumption
First, let’s understand the relationship between outside temperature and energy consumption.
First of all you have to understand that a compressor is the engine of an AC. As soon as you switch on the air conditioner, the compressor starts running and its speed determines the speed of cooling. It means that a compressor running at full speed will use more power as compared to when it is running at variable speed.
When you turn on the AC, the compressor tries to lower the temperature down as fast as possible by reaching high speed in short time. When the desired temperature is reached, the compressor starts running at variable speed to keep the temperature constant. Basically it lowers it speed for some time, and when the temperature starts going up (say by 0.5 degrees), it increases the speed to lower the temperature again. Now in both these cases the outside temperature plays an important role. Why?
Let’s understand this with an example. If outside temperature is 40 °C and you set the AC temperature at 18 °C, the compressor will have to work till it reaches 18 °C and then, it will decrease its speed. But, because the outside temperature is high, the temperature will start increasing again quickly and the compressor will have to increase its speed within short period. You can imagine, that the compressor will not have to work this hard if the AC temperature is set at 26 °C.
This is one of the reasons why in a hot country like India, higher temperature is better for energy efficiency. The chart below shows how much energy you can save when you set the AC temperature to 18 °C, 24 °C and 27 °C.
|Temperature||Total units used /day||Cost of power / month||% Saving vs 18°C|
|27 °C||9 units||Rs 1755||30.8%|
|24 °C||10.5 units||Rs 2047||19.2%|
|18 °C||13 units||Rs 2535|
Source: TERI (Conditions of New Delhi)
As you can see higher temperature saves more electricity. Also, as per study by American Council, for every single degree increase in AC temperature, you save 3-5% power. Based on the chart above we come to following conclusions:
- Increasing AC temperature from 18°C to 27°C will save around Rs 6,240 per year
- Increasing the temperature from 18°C to 24°C will help in saving Rs 3,900 per year.
- Below 24 °C, energy savings on every 1 degree temperature is 6%, while above 24 °C, saving on every 1 degree is 4%.
Best Temperature For AC As Per Season & Weather
Human body temperature is 36-37 degrees. On top of this, our body gets attuned to the hot weather as the season progresses from spring to summer. This is the reason why AC temperature should be set to higher level during summers and not lower. As per TERI School of Advanced Studies, best temperature for AC during summers is 28°C.
On the other hand, ideal temperature for AC during winters is 23°C.
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Ideal AC Temperature for Human Body
As discussed, normal human body temperature is 36-37°C. Therefore, temperatures up to 25 degrees is quite comfortable for human body.
According to ASHRAE (American Society of Heating, Refrigerating and Air-Conditioning Engineers) Standard 55-2013 Thermal Environmental Conditions for Human Occupancy, in order to achieve the desired comfort level the temperature setting should be 24-25°C.
On the other hand, 18 – 21°C is not only uncomfortable but also unhealthy.
10 Tips to Save Electricity & Get Best Temperature Settings
1. One way to save money is to allow the AC to turn off either automatically or manually once the indoor temperature reaches the desired level. You may want to do this at night since lesser temperature at night will aid in keeping the room cooler for longer time.
2. Set the temperature at higher settings of 27-28 °C. This will save decent amount of electricity.
3. Don’t set the temperature to minimum 18 °C if you want to cool the room fast. It is a myth that setting AC temperature to low temperature will cool faster. It only leads to higher energy consumption. Instead, set the temperature to desired levels to increase your savings.
4. You can switch the compressor off and keep the AC fan running once the desired temperature is reached. This will allow the indoors to keep cool for longer duration. However, this may not be the best option to use in humid regions.
5. Using ceiling fan along with AC is known to cool the room faster, thus saving more on power consumption.
6. Don’t turn the AC on and off regularly. This will not save power because every time you switch on the AC, the compressor will have to work in higher speed to reach the desired temperature. On top of this, it will also take long time for AC to cool the room from existing higher temperature.
7. This brings us to our next point. That is to use the auto cooling mode rather than setting the temperature of AC manually. This is especially useful if you are living in hot and humid region.
8. Don’t change the temperature from time to time. Set one temperature and stick to it. This will save decent amount of electricity.
9. A thermostat in an AC does not understand the difference between different types of heat. TV, laptop, phones and other electronic equipment produce heat. AC may not work best when these equipment are present in the room and turned on. You may want to switch them off while using the AC.
10. To help maintain ideal AC temperature to save electricity, it is always recommended that you clean the filter and aerator regularly. If filters and aerators are not kept clean, they will get clogged with dirt. This will decrease the overall efficiency of AC because it will have to work harder to get to the same temperature. Thus, you should clean them at least every three months, especially during regular usage.