8 degrees cooler in 3 minutes? Nonsense!
10-8-2026
Translation: Elicia Payne
Desperate people do questionable things. Some buy a «mini air conditioner» that promises miracles. What they don’t realise: you can’t outsmart physics.
Yes, you can find them on Galaxus. They’re small, compact devices with names that promise to cool you down, such as «Arctic Air» or «Eva Chill».
That’s right, you’ll find them in the «Air Conditioning» section. However, they have little in common with «real» air conditioning systems. These are air coolers – in other words, a kind of advanced fan. The devices draw in warm air and direct it through a pad or filter containing water. As the water evaporates, evaporation chill is generated directly in front of the unit.
This effect may well reduce the temperature by a few degrees around the unit. But that has nothing to do with how air conditioners work. They use a compressor that transfers hot air out of the room to the outdoors.
Proven by physics
Back to the alleged wonder devices. Their effects are limited and they don’t cool your room. That’s not possible. After all, you can’t change the laws of physics.
The fact that I’m about to explain the first law of thermodynamics would probably amaze my old high school physics teacher. My grades were pretty bad. But you never stop learning. If I can understand it, so can you. Let me start by saying, energy doesn’t just disappear. Heat in a room is, after all, just that. This energy needs to leave the room for it to cool down. That’s why there are split-system units with a compressor and a refrigeration cycle. Monoblock units have a huge pipe that you hang out the window. This is key for the device to work. You can’t just hang up wall-mounted units like this one and hope for a cooling miracle. No, for them to work, you have to drill holes in the outside wall.
Units without a tube can’t remove heat from the room. In fact, quite the opposite. When the unit’s running, it generates additional heat – even if it has just a very small electric motor that draws only a few watts to power a small fan. Regardless how small, it will also generate energy – i.e. heat.
Even if you feel cool when you’re standing right in front of the unit, the room as a whole certainly won’t get any cooler – if anything, it’ll actually get warmer. At the very least, the temperature will increase by one or two tenths of a degree.
Absurd marketing
Fortunately, the air coolers on Galaxus are described in a relatively clear and concise manner. Devices that have been heavily and aggressively advertised online and on social media this summer, however, aren’t. Employees at Heise Online recently took a closer look at these «fake air conditioners» and reported on them here (article in German).
Some devices even come with claims that they were developed by NASA. In their own tests, these «miracle» devices reportedly lowered the temperature from 34 to 17 degrees in two minutes. On top of that, manufacturers make bold claims about power consumption. Thanks to space technology, these devices allegedly consume up to 99 per cent less electricity than traditional air conditioners. The sales department clearly knows how to successfully market the «next-generation air conditioners». In a recent Galaxus survey, many people said they avoid using air conditioners because they use a lot of electricity.
Of course, there aren’t any physicists on the verge of winning the Nobel Prize behind AiraBreeze, AirZuma, Coolizi Coolzy and the like. According to an investigation by Heise Online, these are shady businesspeople who peddle cheap Chinese-made products to willing customers using AI-generated ads and fake websites complete with enthusiastic but fabricated customer reviews.
A teeny bit cooler, way more humidity
What the ads for evaporative coolers say isn’t a complete lie. Although the principle behind it is ancient, it does in fact work. As I briefly mentioned above, they work by pushing air past water. That’s why these machines have small tanks – you can also add ice cubes to some of them. The ice or water evaporates, producing evaporation chill. This means the airflow is a few degrees cooler than the surrounding air – but significantly more humid. Consumer-affairs show, Kassensturz, also found this when they tested these devices last year. Plus, they found that the water pads and filters are prone to mould.
The «cold» airflow from evaporative coolers stays very close to the device. Small ones cool the air within a range of ten to twenty centimetres directly in front of the device. That’s why the manufacturers are presenting the devices on nightstands or on desks next to a monitor. If you place a thermometer directly in the airflow, you’ll actually measure lower temperatures. But, as soon as the air circulates throughout the room, the room temperature will return to normal. And the moisture doesn’t go anywhere.
That’s the problem. After all, what we perceive as heat isn’t simply the air temperature, but rather how well our bodies can release their own heat into the environment. We do this by sweating – more easily in dry air, but poorly in humid air. In other words, dry heat is easier to put up with than humid heat. Like higher temperatures that are easier to handle in the sauna than in the steam room.
Only useful in dry heat
When you run an evaporative cooler, the humidity in the room increases. In Switzerland, summer is often humid. That’s why a room with a «mini air conditioner» in it may feel even more stifling than before. A device like this is only useful in dry climates, where the air can easily absorb the additional moisture. If you’re travelling to Arizona, Iraq, Morocco or the Australian outback – go ahead and pack one of these.
You can even run some of these evaporative coolers with a power bank because they need very little power. Not surprising when the units don’t actually do any major physical cooling work. Essentially, they just move air over a damp sponge.
What about ice?
Devices that are filled with ice instead of water are interesting from a physics perspective. When ice melts, it actually draws heat from the air, as physicist and science journalist Florian Aigner recently demonstrated in a column on futurezone.at (website in German). But this ice is usually made in a freezer – and that’s usually in your apartment, too. The waste heat generated by the freezer during the freezing process warms up the room more than the ice cools it down afterward. All in all, it’s a no-win situation.
Honest and affordable: the fan
So we’ve established there are no miracle coolers for a low price, as much as we’d all like there to be. If you can’t vent hot air out of the room, you won’t actually cool the room down. That’s physics. And it applies to every device, regardless of its name or what’s written on the packaging.
If you don’t have real air conditioning, tried-and-true methods can help: keep windows and blinds closed during the day, and let fresh air in at night or early in the morning. If you’re going to buy a device, go for a good fan. It doesn’t cool the air in the room either, but it doesn’t claim to do that. It still has a cooling effect on the skin because it helps your sweat evaporate more quickly.
Header image: Martin Jungfer
Martin Jungfer
Head of Content
Martin.Jungfer@digitecgalaxus.chJournalist since 1997. Stopovers in Franconia (or the Franken region), Lake Constance, Obwalden, Nidwalden and Zurich. Father since 2014. Expert in editorial organisation and motivation. Focus on sustainability, home office tools, beautiful things for the home, creative toys and sports equipment.
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