How high should the air conditioner be set?

Hot in one word!

The dog days of summer have begun, and temperatures are reaching new highs everywhere. Not only have there been many cases of heat stroke, but people are also forced to crawl under the shade of trees even if they have broken six ribs... Faced with such high temperatures, the thing that can best save our lives is air conditioning.

Tuchong Creative

So how high should the air conditioner be set?

Some people turn the temperature as low as possible to keep cool, some believe 26℃ is the most comfortable and energy-saving, and some say 28℃ is the most suitable. So which statement is correct?

Let me first state the conclusion:

The most suitable temperature for air conditioning is not necessarily 26℃ or 28℃, but setting the temperature higher does save more electricity.

Let’s talk about it in detail below.

01

Adjust one degree, what happened?

We all know that air conditioners are power hogs. They consume a lot of electricity, and the lower the temperature is set, the more electricity they consume. But how much does power consumption actually change? According to a 2015 study of air conditioners in a room in Maoming, Guangdong, it was found that if the air conditioner setting temperature was reduced from 26°C to 25°C, power consumption would increase by 47.89%. If the air conditioner setting temperature was reduced from 27°C to 25°C, power consumption would increase by 134.35%, which is equivalent to multiplying power consumption by two and adding a little more [1]. So, don’t underestimate this small change of one or two degrees. It can have a significant impact.

Tuchong Creative

Of course, the power consumption of air conditioners is affected by many parameters, including meteorological conditions such as temperature, humidity, wind speed in the area, the energy efficiency level of the air conditioner itself, the refrigerant used, the structure of the air conditioner, etc. The impact of raising the set temperature by one degree may not be the same, but many experiments have shown that the general trend is still "raise the temperature by one degree and save a little electricity."

So what about on a macro scale?

According to the 2013 China Building Energy Conservation Annual Development Research Report, even in 2011, the power consumption of air conditioners in urban residential buildings in my country reached 52 billion kW·h, equivalent to 16.03 million tons of coal, accounting for 10.4% of the total residential energy consumption. Based on this number, if everyone can raise the temperature of their air conditioners by 1°C, how much electricity can be saved?

Tuchong Creative

At this point, it is necessary to correct a misunderstanding, that is, some friends set the air conditioner temperature to a very low level in the hope of making the air conditioner cool quickly, but this method is not reliable. Because the working method of the air conditioner is to "circulate and cool the air in the room as quickly as possible, and let the room temperature reach the set temperature and then maintain it", rather than "directly spraying cold air at the set temperature", so the set temperature does not actually affect the temperature of the air blown out by the air conditioner, and if you forget to adjust it back... then the cold wind will blow, and the electricity bill will soar...

02

Is there really an optimal temperature for air conditioning?

In fact, if you look into it in detail, the correct setting for the air conditioner is a very complicated matter, because people’s feeling of “coolness” is subjective. In addition, if you want to optimize it to the extreme, you also need to consider the indoor and outdoor environment’s temperature, humidity, wall heat conduction, sunlight, dynamic changes in the room, etc. [2].

In fact, this is also an important topic for engineers. They need to predict the temperature change curve of the day based on meteorological data and models, model and calculate various conditions in the building, measure people's comfort, and allow the air-conditioning set temperature to be dynamically adjusted according to specific circumstances to achieve the goal of energy conservation and emission reduction. Therefore, it is probably not possible to simply say that there is a most suitable set temperature for the air conditioner.

Of course, such fine control is often used in large office buildings. There is no need for such precision in our own homes. As long as you can make yourself comfortable, you can adjust the temperature a little higher. 26℃ to 30℃ are all acceptable. During the day, when people at home are active, you can adjust the temperature a little lower. At night, when people need to sleep, you can just adjust the temperature a little higher and set a time.

03

Turn on the air conditioner like this to save electricity and be healthy

Many friends who like to use air conditioning may feel a little aggrieved. Although setting the temperature higher can save energy, it is still really hot. This feeling is understandable. Let's talk about how to use the air conditioner better.

First of all, we need to know that low temperatures will make us cool, but if we want to feel cool, there are more than one way to cool down. For example, we can use a small fan such as an air circulation fan at home to circulate the air in the house, which helps to make the temperature in the house more evenly distributed, and the breeze can also help us feel cool. Letting the air outlet of the air conditioner face the roof can also help cool the whole house. In addition, make sure that the air conditioner is not blocked to prevent it from misjudging the temperature in the house. The humidity of the air will also greatly affect our feeling of "heat", so if the humidity is too high, remember to turn on the dehumidifier, and don't just lower the temperature.

Tuchong Creative

As for those friends who turn the air conditioner on very low and cover themselves with quilts...why don't we take off the quilts first.

When it comes to air conditioning, there are two groups of people who need special attention. The first is babies. They have a high metabolism and sweat easily in summer. Long-term use can easily cause skin problems such as prickly heat, which can make babies itchy and painful and even affect their sleep. Therefore, it is necessary to turn on the air conditioner to cool down. It should be noted that the air outlet must be adjusted properly and cannot be blown directly.

Then there are the elderly, whose metabolism slows down and they are prone to feeling cold, and many of them also have cardiovascular and cerebrovascular diseases. In this case, the air conditioner temperature should not be set too low, especially the temperature difference with the outdoor temperature should not be too large, so as to avoid sudden cold and heat when entering and leaving the house, which may induce cardiovascular and cerebrovascular diseases. Therefore, many doctors recommend that the air conditioner in the elderly's home be set to 28℃.

In conclusion, we don’t need to worry too much about what temperature is the most suitable for the air conditioner. Any temperature between 26℃ and 30℃ is fine. But we should also remember that if we feel it is cool enough, we can press the remote control to turn up the air conditioner by one degree. This will not only help save energy but also save electricity bills. In addition, don’t forget to ventilate the room regularly.

Author | Ding Zong

Review | Qin Zongmin Member of the Chinese Society of Refrigeration Senior Engineer

References:

[1] Wang Qian, Meng Qinglin. Field study on the effect of air conditioner set temperature on power consumption in summer[J]. Building Energy Conservation, 2015, 43(11):5.

[2] Ma Qing, Li Qiqiang, Nie Qingzhen. Research on dynamic optimization control of air conditioning temperature setpoint in public buildings[J]. Journal of Systems Engineering, 2011, 26(4):7.

This article is produced by the "Science Rumor Refutation Platform" (ID: Science_Facts). Please indicate the source when reprinting.

The pictures in this article are from the copyright gallery and are not authorized for reproduction.