What temperature should I set my air conditioning to?

When people install air conditioning, one of the first questions they ask is what temperature they should actually set it to. It sounds simple, but there is not one fixed number that suits every home, every room and every person.

For most households, the best approach is to start around 24 to 26°C and adjust from there. That range is usually cool enough to make the room more comfortable without driving running costs up unnecessarily.

Why 24 to 26°C is usually the best starting point

Many people assume colder always means better. In reality, setting your air conditioning too low does not cool the room instantly. It simply tells the system to keep working until it reaches that lower target.

That is why 24 to 26°C is often the best balance between comfort and efficiency. It allows the system to cool the room properly without forcing it to work harder than it needs to.

In a UK home, that is usually enough to take the edge off a warm room and make the space feel comfortable without making it feel too cold.

What happens if you set it too low?

If you set your air conditioning to 18 or 19°C on a warm day, the system will usually run for longer and use more electricity. That can increase running costs without necessarily making the room feel better.

Very low settings can also make a room feel too cold, especially in bedrooms or smaller spaces. Instead of creating steady comfort, the room can start to feel draughty or uneven.

A better approach is to start at 25°C, give the room time to cool, and then adjust slightly if needed. In many cases, changing the temperature by just one degree is enough.

Best air conditioning temperature for saving money

If your main goal is efficiency, a slightly higher setting will usually cost less to run. The lower the temperature target, the harder the system has to work.

For many homes, 25 or 26°C will feel comfortable once the room has cooled down properly. This is especially true if you also reduce heat build-up during the day by closing blinds or curtains, limiting direct sunlight and keeping windows shut when it is hotter outside.

Air conditioning works best when it is part of an overall approach to keeping the home cool, rather than trying to fight against direct sun, warm air and built-up heat on its own.

Best temperature for sleeping with air conditioning

Bedrooms are slightly different because people often prefer a cooler room at night.

For sleep, a setting of around 22 to 24°C is often a good place to start. That may feel more comfortable for sleeping than a daytime living space, especially during warm weather.

However, there is still no need to set the unit very low. The aim is to keep the room comfortably cool and stable, not cold. If the room feels chilly overnight, raise the setting slightly rather than turning the unit on and off repeatedly.

Best temperature for living rooms and day-to-day use

In living rooms, home offices and other daytime spaces, 24 to 26°C is usually the most practical range.

These rooms often have more movement, more heat from appliances and more people coming and going. A setting in this range usually keeps the room comfortable while helping the system run efficiently.

If a room gets strong afternoon sun, you may prefer to start at the lower end of that range. If it stays shaded and well insulated, the higher end may be enough.

What temperature should I set my air conditioning to when I am out?

If you are leaving the house for a short period, there is usually no need to turn the system very low before you go. It often makes more sense to use timers or smart controls so the room is cooled shortly before you return.

If you are going out for most of the day, you may prefer to switch the system off or set it slightly higher so it is not cooling an empty home unnecessarily.

The best option depends on how quickly your home warms up, how well it holds cool air and whether the room gets direct sun during the day.

Do smart controls make a difference?

Smart controls can help you get more from your air conditioning because they make it easier to manage temperature throughout the day.

Instead of setting one temperature and forgetting about it, you can use timers or schedules to match cooling to when you are actually in the room. That can improve comfort and reduce unnecessary running costs.

Even simple controls can make a difference if they help you avoid overcooling the home or leaving the system running when it is not needed.

Common mistakes people make with air conditioning settings

One of the most common mistakes is setting the temperature too low in the hope that the room will cool faster. In practice, this usually just increases energy use.

Another mistake is adjusting the thermostat constantly. Air conditioning works better when it maintains a steady temperature rather than being pushed up and down throughout the day.

Some people also ignore how the room itself affects comfort. Strong sunlight, open windows, cooking, appliances and poor insulation can all make a big difference to how well the system performs.

How room conditions affect the best setting

The right temperature is not only about the unit itself. It also depends on how your home holds and gains heat.

A south-facing room with large windows may need a lower setting than a shaded bedroom. A well-insulated room may stay comfortable for longer, while a room with a lot of heat build-up may need the system to run more often.

That is why the best setting is always a starting point rather than a strict rule. The goal is to find the highest comfortable setting that still keeps the room cool enough for how you use it.

Can the right setting help lower running costs?

Yes, in many cases it can.

If the system is set lower than necessary, it will generally run for longer and use more electricity. A slightly higher setting can reduce that demand while still keeping the room cool enough to feel comfortable.

That does not mean you should tolerate a room that feels too warm. It means the most efficient setting is usually the highest temperature that still feels comfortable for the room, time of day and weather outside.

What is the best way to find the right temperature?

The easiest way is to start at 25°C and then adjust gradually.

If the room still feels too warm, lower it by one degree. If it feels colder than it needs to be, raise it slightly. After a short period, most households find a setting that feels right for their space.

This usually works better than starting very low and trying to work backwards.

Finding the right air conditioning setting for your home

The best air conditioning temperature is not the coldest setting. It is the setting that keeps your room comfortable while allowing the system to run efficiently.

For most UK homes, that means starting around 24 to 26°C during the day and adjusting slightly depending on the room, the weather and personal comfort. Bedrooms often suit a slightly cooler setting, while living areas usually work well within the standard range.

A good setup should feel steady and comfortable, not overly cold. If your air conditioning is sized properly and set sensibly, it should cool the room without wasting energy.

How iHeat can help

Choosing the right air conditioning temperature is only part of the picture. The size of the unit, the layout of the room and how well the system is matched to the property all affect comfort and efficiency.

A well-designed air conditioning system should cool the space effectively without needing to be set unnecessarily low. That helps improve comfort and keep running costs under control.

iHeat installs air conditioning systems designed for modern homes, helping households create a more comfortable indoor environment with efficient, reliable cooling.