--- title: "Do evaporative air coolers work in the UK? | Home Comfort Lab" description: "How air coolers work, why they struggle in humid weather, and when a fan or air conditioner is the better buy." url: https://homecomfortlab.co.uk/cool/do-evaporative-coolers-work/ --- # Do evaporative air coolers work in the UK? How air coolers work, why they struggle in humid weather, and when a fan or air conditioner is the better buy. By [Pete Harvey](https://homecomfortlab.co.uk/about/), editor. Updated 14 October 2026. This page links to Amazon. As an Amazon Associate I earn from qualifying purchases. [More about how this site is paid for](https://homecomfortlab.co.uk/affiliate-disclosure/). ![On a humid, cloudy day an evaporative air cooler blows slightly cooler air while moisture builds up in the room.](https://homecomfortlab.co.uk/images/scenes/do-evaporative-coolers-work.svg) > **The short answer** > > Only a little, and mainly in dry weather. An evaporative cooler blows air through a wet pad, and the water that evaporates takes some heat out of the air. In humid weather less water evaporates, so the cooling is small, and the moisture it adds makes the room feel muggier. On a humid day a fan does as much for you for less, and only an air conditioner lowers the temperature of the whole room. ## How an evaporative cooler works It works the same way sweat cools your skin. Turning liquid water into vapour takes energy, and the water takes that energy from the air around it as heat. An evaporative cooler (often sold as an "air cooler") has a water tank, a pad or filter that soaks up the water, and a fan. The fan pulls room air through the wet pad, some of the water evaporates, and the air that comes out the front is a little cooler and more moist. Nothing carries heat outside, the way an air conditioner's exhaust hose does. The air the cooler blows out is cooler than the air it took in, but the room as a whole gains moisture with every hour it runs. > **How to spot one in a listing** > > Some evaporative coolers look like portable air conditioners in photos and listings. A portable air conditioner has a wide exhaust hose that goes out of a window. If there's no hose and there's a water tank, it is an evaporative cooler. ## Why humid air makes them struggle Water evaporates fastest into dry air. When the air already holds a lot of moisture, less water evaporates from the pad, so less heat is taken out and the air coming out is barely cooler than the air going in. The US Department of Energy, writing about evaporative coolers for American homes, says they are only suitable for areas with low humidity and shouldn't be used in humid climates, because they add humidity to your home. There's a second problem. Humid air also slows down the evaporation of sweat from your skin, which is how your body cools itself. So as the cooler raises the humidity in a closed room, you can end up feeling stickier and no cooler. ## The damp problem Adding water to the air of a closed bedroom is what the rest of this site warns against in winter. The US Department of Energy notes that if windows aren't open far enough, humidity builds up in the home. Run an evaporative cooler with the windows shut and the humidity in the room climbs, and humidity that stays high for days is what lets mould grow. Humidity scale: below 40% is too dry, 40–60% is comfortable, 60–70% is damp, and above 70% is a mould risk. A hygrometer tells you where your room sits on that scale. If it already reads in the damp range on a hot day, an evaporative cooler will push it higher. [The ideal humidity for a home](https://homecomfortlab.co.uk/damp/ideal-indoor-humidity/) explains the ranges. ## When one might help An evaporative cooler is worth considering only when all of these are true: - your hygrometer shows the air in the room is dry on hot days, towards the low end of the scale above - you can keep a window open while it runs, so the extra moisture has somewhere to go - you'll sit close to it, in the airflow, rather than expecting it to cool the whole room - you're happy to fill the tank, and to empty and clean it as the manual says so the water doesn't go stale ## Compared with a fan or an air conditioner The evaporative cooler in our list is rated at 60W, which costs 1.6p an hour. That is more than the fans, which average 35W, or 0.9p an hour. The portable air conditioners average 847W, or up to 22p an hour. Costs use **26.32p per kWh**, the [Ofgem price cap, Direct Debit average for England, Scotland and Wales](https://ofgem.gov.uk/news/changes-energy-price-cap-between-1-october-and-31-december-2026) for 1 October to 31 December 2026. Your own tariff may differ. [How we calculate](https://homecomfortlab.co.uk/how-we-calculate/). - **A fan** gives you the moving air without the water. On a humid day that is most of what an evaporative cooler does for you, and a fan adds no moisture to the room. See the [best fan for a bedroom](https://homecomfortlab.co.uk/cool/best-fan-for-bedroom/). - **A portable air conditioner** takes heat out of the room and sends it outside, and dries the air as it goes. It costs much more to run, but it is the only one of the three that brings the room temperature down whatever the humidity. See [air conditioner or fan](https://homecomfortlab.co.uk/cool/portable-air-conditioner-vs-fan/). ## If you still want one This pick is chosen by its specs. We haven't tested it, and on a humid UK summer day expect it to feel much like a fan. ### For dry, hot days with a window open Midea Sensicool 7L Air Cooler - **Type:** Evaporative - **Power:** 60W - **Noise:** 28dB - **Tank:** 7 litres - **Cost per hour:** 1.6p * Timer * Remote control It is rated at 60W, or 1.6p an hour. It has a 7 litre water tank. It has a timer, so it can switch itself off. The maker gives its noise as 28dB sound power, which isn't directly comparable with the fan figures. [View on Amazon](https://homecomfortlab.co.uk/go/cooler-evap-a/) [Manufacturer specs](https://www.midea.com/nl-en/air-care/fans-air-coolers/air-cooler) ## Sources - [US Department of Energy, Energy Saver: Evaporative coolers](https://www.energy.gov/energysaver/evaporative-coolers) Checked 15 October 2026. ## Read next - [Portable air conditioner vs fan: which do you need?](https://homecomfortlab.co.uk/cool/portable-air-conditioner-vs-fan/) (Buying guide) What fans and portable air conditioners each do, what they cost to run, and which suits a UK home. - [Fan and portable air conditioner running costs](https://homecomfortlab.co.uk/cool/fan-and-air-conditioner-running-costs/) (Running costs) What fans, portable air conditioners and evaporative coolers cost per hour and per summer month at the current price cap. - [Best fan for a bedroom](https://homecomfortlab.co.uk/cool/best-fan-for-bedroom/) (Buying guide) Which fans are quiet enough to sleep with, cheapest to run overnight, and right for the size of your room. - [How to keep a bedroom cool in a heatwave](https://homecomfortlab.co.uk/cool/how-to-keep-a-bedroom-cool/) (How to) When to open and close windows, how to use a fan properly, and what helps you sleep when the night stays hot. --- As an Amazon Associate I earn from qualifying purchases. Links to shops are marked, and earning from them never decides what we recommend. [How this site is paid for](https://homecomfortlab.co.uk/affiliate-disclosure/). Running costs use 26.32p per kWh for electricity and 7.97p per kWh for gas, the [Ofgem price cap, Direct Debit average for England, Scotland and Wales](https://ofgem.gov.uk/news/changes-energy-price-cap-between-1-october-and-31-december-2026) for 1 October to 31 December 2026.