How much does it cost to run an evaporative air cooler/swamp cooler? Cheap alternative to portable air con units

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I have written about portable air conditioners quite a lot in the past. It is an appliance I have a lot of mixed feelings for. They are massive, ugly, noisy, expensive to buy and expensive to run. They are also a pain to get to work properly with some UK windows.

However, with extreme heat warnings in London for this weekend coming, all of the above will seem like perfectly reasonable sacrifices to make for some relief from the heat.

Glad I don't live in London

Sadly, the cost-of-living crisis is hitting us all hard and blowing £500 on an air conditioning unit that then costs a fiver a day to run is likely not feasible for a lot of people.

Living up north, I don’t have to suffer from the heat too badly and being tight-fisted, I have been content running a pedestal fan at night to keep me cool. But when my bedroom temperature exceeds 25-degrees even that doesn’t cut it, and I sympathise with anyone in warmer cities.

Swamp Cooler

This then leaves us with evaporative air coolers. These are often not so affectionately called swamp coolers because the evaporative process gives you that muggy swamp humidity. Due to this issue, they are not something I have strongly recommended in the past, but due to the massive increase in electricity prices, they are starting to look a lot more appealing.

How does an evaporative air cooler work?

An evaporative air cooler is a simple machine. It is just a fan that passes the air over water, which cools down the air. However, as the water evaporates into the air, the humidity will increase considerably.

If you live in a very humid climate, then the performance won’t be quite as good because the air can only hold so much water, reducing the evaporative process. The UK has moderate humidity so the overall performance isn't going to be as good as some countries.

You can normally improve the performance by using ice in the water chamber to keep the water cold, and most decent air coolers will come with ice packs that you can use.

Evaporative coolers work well when there is plenty of ventilation, so you don’t need to mess around with sealing your windows like an air conditioning unit. Depending on the style of your windows, this can make a significant difference. They should also run quieter than an air con which should make sleeping with it switched on much easier.

In the UK, an evaporative cooler will likely provide the best performance when blowing air on you rather than expecting it to make a significant impact on the overall room temperature.

Advantages of an evaporative air cooler vs air conditioning?

Before I move on to the actual numbers, evaporative coolers have a lot of advantages over air-con units:

  • Considerably cheaper to buy upfront.
  • Considerably cheaper to run.
  • Much easier to set up and use & less ugly. You don’t need to seal your windows, and you don’t have ugly tubes running out of the window.
  • Almost no maintenance and unlikely to break down. It’s just a fan and a big bowl of water.
  • They make far less noise than an air conditioning unit, and you should be able to run one while you sleep, but they won’t be as quiet as some of the near-silent pedestal fans I have used.
  • They are environmentally friendly and have very low carbon monoxide emissions.

Running cost of an evaporative air cooler vs air conditioning in 2022

The current variable tariff from Bulb is 28.0203p per kWh. For easy maths, I will use 28 pence.

When I bought the Inventor Magic 12000BTU it would draw on average around 1200w, which works out at 33.60p per hour to run, more than double the price of last year.

When I was using it, if you are in the same room when it is running, you get immediate relief from the heat with that pleasant cool air being pumped out. However, depending on how well-sealed the room is, it takes a good few hours to properly cool the full room.

I used to run it for about 3 hours before bed, and it made getting to sleep easier, but the room quickly heats back up.

An evaporative air cooler is typically rated at around 70w or 0.07kwh, which makes the running cost about 2p per hour. However, if you are also freezing ice blocks, there will be some cost in making this, but it should be negligible compared to the air con as I found that the running cost of a freezer isn’t actually that bad (it’s just that they are switched on 24/7).

What are the best evaporative air coolers?

Personally, I’d only buy the larger floor-standing models. Desktop models are just not going to make much of a difference.

The performance you get is going to be related to the size of the fan and its water capacity. You may also want to consider the size and shape. The Pro Breeze 10L is going to be a massive unit that looks like a big air con unit, the Princess Smart Air Cooler is more svelte but it won’t perform quite as well.

Last update on 2022-07-24 / Affiliate links / Images from Amazon Product Advertising API

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