Evaporative air coolers (EACs) use water to lower the temperature in a room by passing air over its wet pads soaked with cold water. This draws heat out of the air, creating a pleasant cooling effect. Air coolers are great for cooling the air in dry climates. They work with naturally occurring evaporative processes to create a cooling effect without electricity as air conditioners or fans.

Evaporative Air Coolers-: Types, Pros, Cons & How To Choose

How do evaporative air coolers work?

Evaporative air coolers are designed to reduce the temperature of air by leveraging the natural principle of evaporation. Air is forced into an evaporator, which comes in contact with water or other liquid that absorbs heat from the surrounding air and evaporates.

The machine typically consists of a fan, a water reservoir, and a thick pad that absorbs moisture from its tank. There are also additional controls that help fine-tune results. The fan draws hot air from your room into the machine and blows it across the thick cooling pad.

When hot air from the room passes across the pad, the water molecules draw heat from it. This mechanism reduces the temperature level of the atmosphere significantly (by as much as 20 degrees in some devices). The now cold air is blown back into the room to cool down the ambient temperature.  

Some evaporative coolers may also have additional parts built into them to increase their functionality. Some units have air filters or pads. These help to clean the air and improve air quality while also cooling your home. Other evaporative air coolers feature a water pump to streamline how the cooling pad absorbs water. Additional features may include an ice pack to boost the cooling effect, variable fan speed, remote controls, oscillating features, and so on.

Evaporative air cooling works best in dry climates such as desert regions or areas with high humidity levels prone to muggy summers. This mechanism is more effective for cooling small to medium-sized spaces.  

When using an evaporative air cooler, we advise you to leave the window partially open to allow warm air to escape outside so that cool air can enter. This is one of the significant differences between air coolers and air conditioners. They do not circulate air as air conditioning systems do. Instead, they rely on a supply of steady fresh air in the cooled space.

Types Of Evaporative Air Coolers

Evaporative coolers have become a popular choice for people with air conditioning needs. Suppose your interest is in purchasing one. You should be familiar with the different types available and which type you should go for based on the benefits and limitations of a proposed one.

1. Direct Evaporative Air Coolers

These are often called swamp coolers. Direct Evaporative Air Coolers are designed in dry, arid climates where the surrounding air is hot and dry. Direct Evaporative Air Coolers use very little power because they do not require the water to run through pipes or tubes for cooling purposes.

This type of air cooler works by using a fan that blows air over wet pads. Then it releases calm, moistened air into your home. Direct Evaporative Air Coolers are perfect for dry climates. They can be just as effective (if not more) as a traditional air conditioner while operating with less noise.

The significant advantage of this type of air cooler is that they’re inexpensive, have a low upfront cost, and do not require installation. Once purchased, you plug the device into a power source, fill the tank with water, and start using it. The maintenance requirement for this type of unit is also minimal.

2. Indirect Evaporative Air Coolers

Indirect evaporative air coolers are remarkably different from direct air coolers. They are not as portable and do not add humidity to the air when cooling a space. However, they are pretty efficient for cooling. They are suitable for large areas such as restaurants, factories, and other commercial spaces because they offer more excellent cooling effects than regular swap coolers.

The principles of operations of indirect evaporative air coolers are similar to that of the direct cooler. The significant difference between them is that indirect cooling further leverages the fact that evaporative cooling is entirely dependent on warm air from outside. Units like this typically have an additional heated air source which allows them to generate more cool air.

The major downside of indirect EACs is their size. They are large, which also means they are pretty expensive to buy, install and operate. In most cases, you will need to install a duct system to carry air to and from the unit. However, they are still a lot cheaper than air conditioners.

3. Mounted Evaporative Air Coolers

Midway between the direct and indirect EACs, we have the mounted air cooler. In the true sense, this does not refer to a specific type of cooler but how the model you have is installed. So you can have direct coolers as either mounted or non-mounted (portable units). Indirect coolers, on the other hand, are permanently mounted. Evaporative air coolers are further classified based on mounted as either ground-mounted, window-mounted, or roof-mounted.

  • Ground-mounting: this type of mounted air cooler is less common mainly because they are not very efficient. Cold falls are more likely to be found at lower levels. Hot air tends to rise, which means excellent air circulation is minor in this type of evaporative cooler.
  • Window-mounting: this is the most common way to mount air coolers, especially for smaller spaces such as office spaces. They offer a fresh supply of air which makes them more efficient.  
  • Roof mounting: this type of evaporative air cooler is more common in commercial or industrial facilities. They can be mount on the roof while air ducts circulate warm and cool air through the unit. Roof-mounted EACs are typically more expensive and more challenging to maintain over time.

Pros And Cons Of Using Evaporative Air Coolers

For starters, evaporative air coolers serve as an affordable alternative for those who cannot afford or do not want to install air conditioning but still need relief from the heat. They are efficient and can typically cool the surrounding area by as much as 15 degrees or more. 

However, they aren’t without some downsides too. Evaporative coolers are not the most effective in humid environments. Plus, they don’t provide as much relief from humidity as air conditioning does. Hence, they’re mostly a good option for those who live in dry climates, typically cooler outside. The following are some of the benefits and drawbacks of EACs.


  • Eco-friendly: evaporative air cooler relies on convention and evaporation’s natural principles, making them environmentally friendly because there are no chemicals/fluids in operation.
  • Cheaper: Evaporative units are less expensive than other types of cooling systems. For central Air conditioning, for instance, in addition to the cost of installation, you also have to pay for electricity usage and continuous maintenance to keep the unit in good condition.
  • Low noise: these types of devices do not generate noise like other cooling systems, which may be desirable if you are trying to sleep or work in your home and need silence.


  • Evaporative air coolers are not very efficient for larger spaces.
  • Evaporative units have a shorter lifespan than other types of cooling systems.
  • The water capacity for these devices is typically small, which means they will need refilling more often when you use them.
  • Evaporative air coolers do not remove humidity like other cooling systems. We don’t recommend this type for use in high-humidity areas. Still, suppose you need to use your evaporative cooler in high-prone humidity surroundings. In that case, you might need to run a dehumidifier alongside. 

How To Get The Most Out Of Your Evaporative Cooler

Now that you know more about what to expect with an evaporative cooler regarding the benefits and drawbacks. It’s good that you learn how to get the most out of your evaporative cooler.

  • Consider the size:

The first step is to understand what you’re paying for when purchasing an evaporative cooler. The initial cost will be a function of its size, so if you buy one with more wet pads (i.e., greater surface area), you will pay more than if it has fewer wet pads. However, you will enjoy more significant cooling effects since the wet pad is the primary mechanism that cools warm air. Therefore, the more substantial the surface area, the more efficient the unit.

Before you make a purchase, it is wise to measure the size of your space and compare it to how much space the evaporative air cooler can cover. You may need to get more than one cooler for large areas or figure out a way to direct the fan towards where you need it the most if the fan isn’t large enough.

  • Positioning matters

Next, you should find a way to anchor your evaporative cooler to maximize the amount of air flowing through it and around you. This means considering where you’ll place it outside so that there is minimal blockage for airflow.

  • Open the windows:

It would be best if you kept the windows open when the unit is operating. Evaporative coolers are a lot different from conventional air conditioners. You don’t have to keep the indoor air tightly sealed to keep it cold. Evaporative coolers depend on having steady supply of fresh air. Opening the window close to the unit’s intake fan allows a dry and warm atmosphere to be more relaxed and makes evaporation quicker. 

Opening the window also allows humidified air to escape as it comes out from the cooler. If you neglect this, the air will become humid and clammy. You don’t have to open the window widely; with time, you will figure out how to crack the window open slightly for optimal comfort. 

  • Keep the pads wet:

Make sure to keep the wet pads moist. We recommend using distilled water or natural rainwater because it will help cool you down even more. It will also not contribute to dry skin as tap water can do over time. You should also have a drainage system for when your cooler gets too full of water.

  • Always keep the water supply fresh and clean:

If you will not be using the cooler for a while, empty the tank and clean it, which is necessary to prevent mold growth. Regular cleaning will ensure that your evaporative cooler functions well and keep the air quality clean.

How To Choose The Best Air Cooler-: Relevant Features To Know

There are many different types of evaporative air coolers on the market. Not all can provide the same level of cooling, so it is essential to be knowledgeable before purchasing. Here are notable features you should know about for choosing the best evaporative air cooler for your home:

1. Size: 

You need to choose the size that will work for your space. Do you have a large area, or are you looking for something more compact? Suppose your choice of an evaporative air cooler is too small for your space. In that case, you will need to keep it running for a long time to cool your room correctly, thereby spending more on energy. Some of the factor to consider as far as size is concerned includes:

  • The CMH: Cubic meters per hour are used to measure the amount of airflow needed to cool your space effectively. You can calculate this by multiplying the volume of your room (using the height, length, and breadth). Also, the number of air cycles needed to cool the area (most spaces need about 20 to 30 air cycles). So for a 150 square meters room, you will need a unit with about 3000 to 4500 CMH. 
  • Tank Capacity & water usage: Some air coolers on the market use much more water than others. Find out how much water your chosen model will need to operate effectively and stay within your budget. Generally, the tank capacity will determine how long the unit can run. The larger the reservoir, the longer the air cooler will run before the tank needs to be refilled again.

The trick is to select an evaporative air cooler with a reservoir that is just the right size for your daily use. If your room is large, then the tank of your air cooler should be significant as well. Why? Because the tank capacity of residential and commercial units of air coolers are remarkably different. While residential coolers can make do with units with 20-30 liter tanks, commercial units may have up to 120-liter capacity. 

  • Portability: The ease of moving the unit around is essential in sizing your evaporative air cooler correctly. This is particularly important for a non-mounted machine that you want to move from one room to another. Many portable air coolers feature rolling wheels that make it easier to change their position when you need to. 
2. The number, quality, and thickness of cooling pads

The cooling pad is the primary mechanism that an evaporative air cooler uses to cool the air. It absorbs water and cools warm air as it flows through the unit. The thicker the cooling pads are, the more efficient the device will be as far as cooling is concerned. You also have to consider the number of cooling pads in the EAC. Some units only have one cooling pad, while others may have as much as four. The cooling impact of the air cooler gets better as the number of cooling pads increases.

The quality of the pads matters should also be check. Generally, cooling pads are either made of cellulose or aspen materials. Each of these material types has specific pros and cons. 

  • Aspen pad is a combination of synthetic fiber and wood shavings. Coolers with this type of pad are typically cheaper. But they have a shorter lifespan and require more maintenance.  
  • Cellulose pads, on the other hand, are thicker and more efficient. They have a honeycomb structure which is why they are also called honeycomb pads, and it does not require as much maintenance as aspen pads. Still, units with this type of pad tend to be more expensive.
3. The Fan: 

The best evaporative air coolers have a water reservoir that is large and well-sealed, along with a high-quality fan to increase airflow. Evaporative coolers can be equipped with an axial fan or a centrifugal fan. Units with centrifugal fans are generally less loud, but they need more energy to operate. On the other hand, axial fans don’t cost much energy but are noisier.

4. Durability: 

The evaporative air cooler’s material will determine how well it can withstand various climates. A high-quality, durable metal roof or walled stainless steel body will do a much better job of cooling your space than other materials such as canvas and plastic.

Additional features
  • Water level indicator: a unit with a water level indicator will be more convenient to use than one without it. However, an indicator may not be necessary if your air cooler is connected directly to a water source and circulates water efficiently.
  • Castors: castors enhance the portability of air coolers. You should watch out for the material of this castor as it goes a long way in determining its durability, especially if you plan to move the unit around frequently. Plastic castors will not last as long as those made with thick rubber or metal material.
  • Remote control: this is particularly important for a portable unit with intelligent features and additional settings. A product with remote control allows quick access to these settings.

Evaporative air coolers vs. Conventional air conditioners

Evaporative air coolers are often tag as the eco-friendly alternative to traditional air conditioners. Unlike their refrigerant-driven counterparts, an evaporative cooler relies on a natural cooling cycle. The hot outside air is drawn in and passed over water-soaked pads before being blown out into your living space. This process not only keeps you more comfortable but is also suitable for your air quality.

In addition to being harsher on the environment, a traditional air conditioner is more expensive to operate than an evaporative cooler because of the refrigerant it uses. The upfront installation cost is higher (many EACs don’t require installation at all). They also cost more in terms of energy usage than evaporative coolers.

However, an air conditioner will usually give you more cooling power than an evaporative cooler. This is because refrigerants are better at condensing heat than the cooling effect from evaporation. Evaporative units also have to be refilled with water periodically during operation. They don’t have as much power as AC units, and they’re less economical for larger spaces. Evaporative air coolers also don’t perform well in humid climates because they add moisture to the air.

In summary, both air conditioners and evaporative coolers provide a great way to stay relaxed and comfortable during the summer months. Which of them to go depends mainly on where you live, how much cooling power you desire and how much you are willing to spend?


Evaporative air coolers have become quite popular in recent years mainly because of their affordability, ease of use, and efficiency. Using an air cooler, you may be able to reduce indoor temperatures by as much as 50% using the natural principles of evaporation. Based on their size, power consumption, pad type, and fan quality, there are many different kinds. It is essential that you carefully consider your options to select the one that will be most efficient for you based on your specific needs.