When the heat becomes difficult to bear, the first impulse is to turn on the air conditioner and lower the thermostat as much as possible. But setting it to 18 degrees does not mean that the room cools down more quickly: rather, it increases the risk of unnecessarily prolonging operation, lowering the temperature too much and wasting energy. And this is just one of the most common mistakes we make with our air conditioner at home: they cost us money – seeing the bills – and can even make us feel worse.
The ABC of air conditioning in the home
To make the best use of the air conditioner you need to act on three elements: temperature, humidity and heat that enters the home. The rule of thumb is to set a temperature that is not too low, close doors and windows while the appliance is on, block the sun during the hottest hours and use programs, timers and operating modes based on the actual conditions of the room.
How many degrees to set the air conditioner at
The indication on the ideal temperature comes directly from the Ministry of Health: simply set an internal temperature between 25 and 27 degrees from your air conditioner remote control, accompanied by a low level of humidity. Does this seem like little to you?
Enea also indicates 26 degrees as a reference for summer air conditioning and remembers that, in many situations, two or three degrees less than the outside temperature may be enough. The temperature must however be evaluated considering who occupies the house. Very young children, elderly people, people with chronic pathologies or with a reduced ability to regulate body temperature may be more exposed to the effects of heat.
Does lowering the air conditioner to 18 degrees cool faster?
Straight answer: no. There is a specific reason why this reasoning is wrong. Setting a temperature much lower than desired does not automatically increase the rate at which the air conditioner removes heat from the room. The only result is to consume more and end up with higher electricity bills.
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Better to immediately set the desired final temperature, for example 26 degrees, and let the machine gradually reach the established level.
Cool, Dry and Fan: which mode to use to cool first
The remote control symbols are not equivalent. Choosing the correct function allows you to improve comfort without asking the machine more work than necessary.
The “Cool” mode, i.e. cold, is symbolized by the snowflake. It’s the normal cool down schedule. It should be used when the room temperature is actually too high. The air conditioner removes heat from the environment until it reaches the value set on the thermostat. As mentioned, you can start from 26 degrees, avoiding constantly changing the setting. In inverter models, once it approaches the required temperature, the compressor can progressively reduce power instead of always operating at maximum.
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In the “Dry” dehumidification mode, the symbol is the drop: it mainly serves to reduce humidity and is useful on muggy days, when the temperature is not extreme but the air appears heavy and sweating evaporates with difficulty.
The “Fan” function circulates the air without necessarily activating cooling. Like a normal fan, it can increase the perceived coolness, but does not lower the temperature of the room. But it creates an illusion that is sometimes enough: according to Enea, the movement of the air can make one perceive up to three degrees less with limited electricity consumption. However, the Ministry of Health specifies that, when the internal temperature exceeds 32 degrees, the fan is no longer an effective tool to counteract the effects of the heat and can promote dehydration, especially in fragile people.
Can you sleep with the air conditioner on?
The “Sleep” function gradually changes the operation of the air conditioner during sleep, preventing it from continuing to cool with the same intensity throughout the night. These programs are designed to adapt the temperature to the change in body temperature during rest.
Precise operation varies from model to model. But in any case there is no general ban on using the air conditioner during the night. In general, to sleep with the air conditioning on it is preferable:
- maintain the temperature in the range of about 25-27 degrees;
use the Sleep function, when available;
set the timer if you don’t need to cool all night;
prevent the room from becoming much colder than other environments;
keep filters, fans and condensate drain clean.
Is it better to keep it on or turn it off and on again?
There is no one-size-fits-all answer for every home and appliance. The result depends on the air conditioning technology, building insulation, sun exposure, room size and outside temperature.
Inverter air conditioners are particularly suitable when operation is expected for many consecutive hours: these devices can modulate power, reduce noise and maintain a more stable temperature than traditional on-off systems.
The safest rule is to avoid both extremes: you shouldn’t leave the air conditioner on for hours in empty rooms, but you shouldn’t wait until the house gets hot and then set a very low temperature.
When to clean the filters
Dirty filters and fans reduce the passage of air and force the machine to work under strain. According to the Enea 2026 guide, a neglected air conditioner can consume up to 30 percent more than the factory parameters.
Cleaning must be carried out before the first seasonal start-up and repeated during periods of intense use, always following the manufacturer’s instructions. The outdoor unit must also be checked, eliminating dust, leaves, pollen and residues that can block grills and fans. Work on the refrigerant circuit, gas or electrical parts must be left to a qualified technician.
The mistakes that make you consume more and increase your bill
First of all, to understand the efficiency of an air conditioner on the energy label it is necessary to check above all the “Eer” value, the seasonal energy efficiency index in cooling: all things being equal, the higher the Eer index, the greater the efficiency of the appliance. A class A+++ model can consume up to 40 percent less than a class B model.
The most frequent mistakes? Set the thermostat to 18 degrees or minimum, leave windows ajar, cool unused rooms, do not block the sun, cover the outdoor unit and forget about maintenance. Computers, ovens, lamps, and other appliances also produce heat. During the hottest hours it is therefore useful to limit, when possible, the use of appliances that further heat the house.
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The principle to remember is simple: the best way to make the air conditioner work less is to prevent heat from entering and humidity from accumulating. Only afterwards come the power of the machine and the temperature set on the remote control.