What is an evaporative cooler?

Broadly speaking, an evaporative cooler is an electrical appliance that lowers the air temperature through the action of a natural refrigerant: water.

Although the first commercial patent dates back to the early 20th century, their popularity has soared in recent years. This is thanks to technological innovations making them increasingly efficient, easy to use, and portable; the savings they offer in terms of both purchase price and maintenance; and a growing social awareness regarding the use of greenhouse gas refrigerants.

For all these reasons, evaporative coolers are now an alternative that can provide more cooling capacity than a fan, while having a lower economic and environmental impact than a conventional air conditioning system.

How do evaporative coolers work?

The operating system of an evaporative cooler is very simple: it draws in warm air from the room, passes it through water-soaked filters to cool it, and then blows it back out using built-in fans.

This is a thermodynamic process so natural that, back in ancient times, it was used to beat the heat in arid regions of Egypt, the Middle East, and India, where damp reed mats were hung by windows to cool the breeze blowing into the home.

Types of evaporative coolers

Over the years, scientific advances have transformed those rudimentary methods into a range of devices suitable for different spaces and needs:

Direct evaporative cooling

In this system, the air passes through the evaporator, cooling and humidifying the room it serves. Direct cooling is the optimal solution for dry spaces that need to be cooled quickly, such as bedrooms or home offices. It is a type of evaporative cooler that works best when temperatures are high and ambient humidity is low.

Indirect evaporative cooling

When both temperature and humidity are high, it is better to use indirect evaporative coolers. In this case, the air passing through the device is cooled using a heat exchanger. This results in cool but dry air, making it ideal for tropical climates and spaces with a higher risk of condensation, such as garages, storerooms, or rooms prone to damp.

Mixed evaporative cooling

Finally, mixed evaporative coolers are the most versatile. In spaces with contrasting conditions, they can act as condensers to reduce air humidity when temperatures are low, but also as wet evaporative cooling systems on hot, dry days. This offers greater adaptability to all types of climates and rooms.

Evaporative cooler, air conditioning, or fan?

Just as when comparing fans and air conditioning units, evaporative coolers can be a viable alternative depending on the case or, in many situations, a complementary solution to the other cooling systems you use at home.

Compared to air conditioning, evaporative cooling is cheaper, easier to install, and more environmentally friendly, as it doesn't use refrigerant gases.

However, both the cooling power and the precision in achieving the desired temperature and humidity are generally higher with air conditioning than with evaporative coolers.

If you want to cool a large space quickly, an evaporative cooler is probably not your best choice; an air conditioning unit would be more suitable. But as a complement, if you have a room that isn't covered by your air conditioning, an evaporative cooler is likely the best option to provide an extra boost.

Compared to fans, evaporative cooling offers – in addition to greater power in most models – a humidifying function that fans lack. And since ventilation is already built into the way the appliance works, you don't usually need to supplement it with extra fans.

Comparison between air conditioning and evaporative coolers:

How to choose an evaporative cooler

Before buying an evaporative cooling unit, it is very useful to review the features that will determine which one best suits your home. Here are some of the details that can influence that decision the most:

Size of the space you need to cool

The size of the room you want to cool will dictate the power of the appliance you need to buy. Getting this right prevents the cooling time from taking too long if it is underpowered, or, conversely, stops electricity consumption from being higher than necessary.

Bear in mind that there are options on the market ranging from 5 W of power for very small spaces, up to 1,500 W or more for industrial models.

Tank capacity and runtime

The cooling function of an evaporative system depends on the temperature of the water in its tank. For this reason, it is important to balance how you plan to use the appliance with the amount of water it can hold. If you won't be using it heavily or continuously, a smaller tank will be sufficient. If you plan to leave the appliance on for a long time, filling a larger tank with very cold water, or even ice, can be a good idea to avoid frequent refills.

Energy consumption and efficiency

Like any other household appliance, evaporative coolers must display an energy efficiency label. To increase your savings and help the environment, at Endesa we will always recommend choosing the model with the best rating. You can spot them by the green colour on the label, which classifies appliances with A, B, and C ratings.

Airflow

Directly linked to power and efficiency, airflow is the amount of cold air the cooler can blow out per hour, measured in cubic metres (m³/h). Consequently, to cool larger rooms in less time, you will need a device with a higher airflow than you would for smaller spaces.

Noise level

With cooling devices, the noise level is a feature that often goes unnoticed when buying, but can make itself known every time you turn the appliance on. It is highly recommended to choose a cooler that isn't disruptive in this regard, since you will likely use it for long periods and even overnight.

Timer and remote control

Timers and remote controls are two additional features that will make your evaporative cooler more convenient to use. Some models let you schedule when they turn on and off, helping to optimise how they run and keep your electricity bill in check.

Advantages of evaporative coolers

Compared to other cooling systems, evaporative coolers have an extensive list of advantages:

• They don't require installation: unlike air conditioning units, the evaporative system doesn't require pipe connections or drilling into walls.
• You don't need to close the room you want to cool: due to the way they work, the air doesn't need to be kept trapped in the room. In fact, it is recommended to keep the space slightly open to refresh the air the device draws in.
• You can move them wherever you need them: most models are portable, as they don't need installing, and their size and design make them easy to move around. This means you can take it from one room to another, or even take it with you if you move house.
• They are sustainable: they don't use greenhouse gases and their energy consumption is lower than air conditioning, as it is practically limited to running the fans.
• They are efficient: thanks to the thermodynamics behind how they work, the hotter the surrounding environment, the more cold air evaporative coolers can produce.
• They refresh the air:  they filter the air, cool it, and spread it around the room, providing a much greater sensation of freshness than any standard fan.

Disadvantages of evaporative coolers

Despite their many advantages, evaporative coolers also have some drawbacks. Taking these into account will help you decide if they are a good solution for cooling your home:

• They are not the best option for closed spaces: since they draw in the surrounding air, it is best to keep the room slightly ventilated.
• They only work for cooling: although indirect systems also help dehumidify the air, thereby reducing the sensation of cold in winter, evaporative coolers cannot radiate heat.
• Their effectiveness depends on external conditions: unlike air conditioning, which works independently of the environment, this type of cooler requires minimum conditions of temperature, ambient humidity, and airflow to work effectively.
• Lower cooling capacity: comparing them once again to air conditioning, the cooling capacity an evaporative cooler can produce is lower, due to both its power and its operating system.