Air conditioning vs fans: which actually cools you?

The honest answer is that fans and air conditioning are not two versions of the same thing. A fan does not lower the temperature of a room. It moves air across your skin, which speeds up the evaporation of sweat and makes you feel cooler, an effect a few degrees strong at best. Air conditioning is different in kind: it removes heat from the room air, genuinely lowers the temperature, and dries the air as it works. So if you only need to feel cooler in the chair you are sitting in, a fan does the job for pennies an hour. If you need the room itself to be cooler and less humid, only air conditioning can do that.

There is one more thing worth knowing before you spend any money: above roughly 35°C a fan can stop helping altogether. Below we explain the physics in plain terms, put real UK running costs side by side, give you a simple rule for when a fan is enough and when you need AC, and point you to the right next step if you decide to upgrade.

Do fans actually cool a room, or just you?

Just you. As the UK retailer Currys puts it, fans "don't actually cool the air, they move it around. This airflow helps sweat evaporate, making you feel cooler without lowering the room temperature." The thermometer on the wall does not move. What changes is the thin layer of warm, humid air sitting against your skin: the fan strips it away and speeds up evaporation, and evaporation carries heat off your body. That is why you feel cooler in the breeze even though the room is exactly as warm as before.

This has a neat, counter-intuitive consequence. Every watt of electricity a fan uses ends up as heat from its motor, so in a sealed room a fan adds a tiny amount of heat rather than removing any. The fan that cools you is, technically, very slightly warming the room. It only feels cooler because of that wind-chill effect on your skin.

The practical takeaway: a fan cools people, not spaces. Leaving one running in an empty room does nothing useful and just wastes electricity. Turn it off when you leave.

What air conditioning does that a fan cannot

An air conditioner uses a refrigerant cycle to extract heat from the room air and dump it outside, which lowers the actual air temperature. As warm room air passes over the cold coil inside the unit, water vapour condenses out of it, so the unit also dehumidifies the room as a by-product of cooling. A fan cannot do either of these things. It has no refrigerant, no thermostat and no way to remove moisture, so it simply circulates the same warm, humid air.

That difference matters most on a muggy night, when the air is heavy and a fan just pushes damp warmth around. Air conditioning lowers both the temperature and the humidity, which is why a cooled room feels fresher rather than just breezier. Reverse-cycle units (the common wall-mounted splits) can also run in reverse to heat the room in winter, so they earn their keep year round.

A fan changes how warm you feel. Air conditioning changes how warm the room is.

Is there a point where a fan stops helping?

Yes, and it is a safety point worth taking seriously. UK health guidance is clear that electric fans only help up to a temperature ceiling. The UK Health Security Agency (UKHSA), in its Beat the Heat advice, says electric fans can help keep you cool when the temperature is below 35°C. Above roughly 35°C the air a fan blows can be hotter than your skin, so instead of carrying heat away it adds heat and speeds up dehydration. Official UK heat guidance also advises against aiming a fan directly at your body in very hot conditions, for the same reason.

So in an ordinary British summer a fan is genuinely useful. In an extreme heatwave it can become worse than useless, and you should not rely on a fan alone to keep you safe. Air conditioning has no such ceiling: it keeps lowering the room temperature regardless of how hot it gets outside.

Is it cheaper to run a fan or air conditioning?

A fan is dramatically cheaper, because it does dramatically less. Most domestic fans draw somewhere between 20 and 100 watts. An air conditioner draws far more, commonly around 1 to 1.5 kilowatts for a portable unit. That is the whole story behind the running-cost gap.

Here is the maths, using the current Ofgem price cap rate of 26.11 pence per kWh (the rate for 1 July to 30 September 2026). The formula is simple and you can repeat it for any appliance: watts divided by 1,000, times hours, times 26.11p.

Put plainly: a 50 W fan run for 8 hours a night costs about 10p a night, roughly £3 a month. A 1 kW portable air conditioner run the same hours costs about £2.09 a night, roughly £63 a month. That makes air conditioning very roughly 15 to 25 times more expensive per hour than a fan, though the exact ratio depends on the unit, the set temperature and the weather. The trade-off is real, but so is what you get for the money: a fan cannot lower the temperature or dry the air at any price.

One efficiency tip that uses both. Running a fan alongside an air conditioner lets you set the AC thermostat a few degrees higher (guidance based on the US Department of Energy suggests about 4°C) without feeling any warmer, because the wind chill makes up the difference. So a fan is not only the cheap alternative to AC; it makes AC cheaper to run.

Prices and rates correct as of July 2026. The energy price cap changes every three months, so check the current rate against your own bill before budgeting.

When a fan is enough, and when you need air conditioning

You do not have to choose between "cheap fan" and "fitted air conditioning" as your only two options. Think of it as a ladder, and climb only as far as your problem demands.

A fan is enough when:

• You mainly need to cool yourself, in one spot, while you are there.

• Daytime temperatures stay in the ordinary British summer range, comfortably below 35°C.

• Humidity is not the problem; you just want some moving air.

• You want the cheapest, install-free option with no regulations to worry about.

You need air conditioning when:

• You need the whole room cooler, not just the breeze on your skin.

• The air is muggy and you want it drier, which a fan cannot do.

• You are trying to keep cool through a genuine heatwave, when a fan can stop helping.

• You want to cool a room nobody is sitting directly in front of, such as a bedroom before you go to sleep or a home office all day.

• You would value reverse-cycle heating in winter from the same unit.

Between the two sits the portable air conditioner: pricier to buy and run than a fan, and noisier than a fitted unit, but it genuinely cools and dries a room with no installation. It is the natural next step for anyone who has decided a fan is not enough but is not ready to commit to a fitted split.

For more on getting the most from whatever you choose, see our guide on how to keep your house cool. If you are weighing up a high-end bladeless fan against the real thing, our explainer on Dyson air conditioning is worth a read, because a Dyson fan is still a fan and does not cool the air.

Fan vs portable AC vs fitted split: which should you buy?

A fan costs from around £15 to £60, with premium bladeless models such as Dyson or Shark running from roughly £199 to £350 or more. A portable air conditioner typically costs in the low hundreds of pounds with no installation. A fitted single split, supplied and installed by an F-Gas certified engineer, runs into four figures depending on capacity and how complex the installation is, but it is by far the most efficient and quietest way to cool a room you use every day.

If you have decided a fan is not enough, our pick of the best portable air conditioners in the UK is the place to start, and you can browse portable air conditioners directly. For the full picture on what cooling actually costs to run, see our running costs guide, and our other buying guides cover choosing a fitted system.

A quick note on the rules: fans are unregulated, with no installation and no refrigerant. Any fixed split, by contrast, must be installed by an F-Gas certified engineer, may involve planning permission for the outdoor unit, and only qualifies for the Boiler Upgrade Scheme in the narrow case of a reverse-cycle unit replacing an existing fossil-fuel or electric heating system, never for comfort cooling alone. Sidestepping all of that is itself a fair point in the "a fan is enough" column.