Are evaporative coolers as good as air conditioners?
If you're asking this question, you're not alone. Air coolers are often much cheaper than air conditioners, more portable, and you don't need to fit or install them. But if you're looking for ice, ice, baby, will you get it?
What is an evaporative cooler?
Evaporative coolers, also known as swamp coolers or personal coolers, are different to regular air conditioners.
An air conditioner, whether it's portable or split system, has a mechanical compressor at its heart. A compressor pushes warm air into a condenser coil. This warm air is turned into cold air, thanks to a liquid refrigerant inside the coils. When the air is pushed back out into the room, it’s easy-breezy cold.
An evaporative air cooler, on the other hand, doesn’t have a compressor or a refrigerant inside it. Instead it uses 4 basic elements - water, a water pump, cooling pads and a fan.
These coolers have an in-built water reservoir that you’ll need to fill up before turning the unit on. Once on, warm, dry air is drawn into the cooler and passes over wet cooling pads that have been soaked in water.
The warm air causes the water on the pads to evaporate. When water evaporates it creates cooler air that’s pushed back into a room via a fan.
The effect can be likened to standing next to a waterfall and getting a cooling breeze off the water, or getting out of a pool and feeling the chill as the air dries the drops on your skin.
Air coolers are not as powerful as air conditioners
This is an important point. Air coolers use an old method of evaporation to cool a space - but they lack the power of modern-day air conditioners and their effective technology.
The lack of a compressor and refrigerant in an evaporative cooler means that if you crave that refreshing blast of icy air on a sweltering day, you won’t get it.
Evaporative coolers can make the air about 1 degree cooler, and rely heavily on a fan for a cooling effect. With some models you can add ice packs to the water, but there’s little evidence that this increases the temperature of the air.
Despite this caveat, portable evaporative coolers are popular with the public. The price of an evaporative cooler is much cheaper than compressor-driven portable ACs. These cheap prices coupled with a need to beat the heat means you might be tempted to buy an air cooler after discovering one on an infomercial or radio ad.
The InstaChill Portable Air Conditioner is a prime example of this - it has lots of interest, but a paltry 1.6-star rating from 90 reviews. Based on reviewers’ opinions on ProductReview.com.au, there are limited situations in which evaporative coolers do the job effectively. Here are some examples of evaporative coolers sold by popular brands.
| Criteria and Product | InstaChill 18EX | Dimplex 7L Evaporative Cooler | Kmart 10 L Evaporative Cooler |
| Rating | 1.6 stars | 1.6 stars | 2.2 stars |
| Price | Upwards of $350 | $299 | $89 |
| Room size | 25m² | 30m² | Unspecified | Main reviewer comments | This is a glorified fan that doesn’t provide any instant chill. It leaves warm air in a room, is expensive and poorly built. | This doesn’t seem to work or circulate air properly. There are also some issues with the water pump. | You can’t feel air blowing out of it, and when you do, it’s not strong. |
What are the other drawbacks of evaporative cooling?
Apart from the fact that their cooling capacity is pretty inadequate compared to air conditioners, here are some other downsides.
If you live in a humid climate or near the water, the condensation a swamp cooler produces will leave a room muggy and uncomfortable to be in. You’ll probably end up feeling more sticky and sweaty than if you weren’t using a cooler at all.
Condensation can build up in a room that’s not well-ventilated. This can cause mould and mildew to grow. Some air coolers have problems with water leaking out of the unit, too, which can damage floors.
You have to keep refilling the water tank. Depending on the model, this can be irritating if you have a small water tank or the unit evaporates water at a high rate. Checking the hourly rate of evaporation will help give you an idea. For example, the De Longhi has a 800mL/hr rate of evaporation and a 4.5-litre water tank. This means you’ll have to refill the tank after about 5.5 hours from full - which isn’t too bad.
What are the advantages of evaporative cooling?
According to manufacturers, there are some cases when an air cooler will work for you. As mentioned above, these situations are pretty limited. You’ll need a specific type of climate, room and physical distance from the unit for the boxes to be ticked.
Air coolers work better in dry, hot climates with low humidity, as increasing humidity won't get too uncomfortable. You should still crack open a window and/or leave doors open, to avoid condensation or mildew from forming inside.
If you have a small space to be cooled (20 m² or less) you’ll be more likely to notice the cooling effects. Evaporative coolers work better as space coolers (for one person, or two at the most). You need to sit close to them, similar to a fan. They don’t do well with circulating air around the room.
Your energy bill will be lower. Swamp coolers have better energy efficiency than your average air conditioner. They have a low power draw, usually averaging around 200-400 watts. It’s tricky to compare power draws in detail, as evaporative coolers and portable ACs aren’t legally required to carry efficiency labels - but it’s safe to say swamp coolers are much cheaper to run than conventional air conditioners, because of their simple operation.
They’re much more eco-friendly than ACs. Not only do air coolers use less power, they also don’t use chemical refrigerants that are harmful to the environment when released into the air.
If you’re renting, you don’t have to bother with exhaust hoses and how to fit them using a window or door kit. An air cooler is a plug-and-go solution.
They can still make a noticeable difference to the temperature inside a small tent. You can read more about using an AC in an tent here.
Wrapping up
Most people are unlikely to be satisfied an evaporative cooler in really hot weather. They just don't have the same cooling power as air conditioners. You may get some relief from an evaporative cooler if you're using it in a very small space, just for you, and your climate is dry, but not too hot.