what is evaporative cooling

Evaporative Cooler – Benefits and Drawbacks of Water Cooling

Evaporative coolers go by several different names.

They are also called air coolers, swamp coolers, desert coolers, personal coolers, and ventless air conditioners.

What is an Evaporative Air Cooler?

An  evaporative cooler is a type of air conditioner that uses water to absorb heat and a fan to blow the water cooled air into a room. It does not generate any heat that needs to be exhausted like that on a standard AC unit.

What is Evaporative Cooling?

Evaporative cooling is a method of cooling down the air in a room by blowing air with a fan through a water soaked pad.

  The air is made cooler because of the capacity of the water to absorb the heat and bring down the temperature of the air.

Evaporative cooling is basically a simulation of air blowing over a body of water similar to the natural process of air cooling off as it blows over a lake or an ocean. Only done mechanically in your home.

  There are more components to an evaporative cooler obviously, but that is the basic premise.

How does an Evaporative Cooler work?

An evaporative cooler works through a simple relationship between a fan motor, a pump, and a rigid pad media too soak with water.

Through a 3 -step process, an evaporative cooler works by:

  1. Pumping water through the use of a water pump onto a rigid pad media to soak the pads through with water.
  2. Blowing a fan through the water soaked pad media into a room
  3. Air is pulled through the room by opening a window on the opposite side of the house or room.

The combination of a fan moving air through a water soaked pad reduces the temperature of the air around 20%

Who can Benefit from an Evaporative Cooler?

1.Rooms with No Windows

Anyone who needs an air conditioner but does not have a way to exhaust the heat generated by the standard window AC or portable AC through a window.

Personal or portable evaporative coolers can be an excellent alternative to window air conditioners or portable air conditioners because they do not need a way to exhaust the heat from them.

Conventional Air conditioners use a refrigeration method that absorbs heat and expels it either through the rear of the air conditioner or with a hose that has to be ducted out of a window.

Portable evaporative coolers do not require any type of heat exhaust, which means they do not have to be near a window. Which makes them actually portable compared to a portable AC that needs a window to exhaust the heat from.

2. Garages

Garages in most cases or not outfitted with the ductwork necessary for the HVAC (central heat and air) to cool off the garage.
A portable evaporative swamp cooler is a great choice to cool down a garage. Not only can you put it anywhere you want in the garage, there is usually outdoor access to a faucet nearby.


If you’re living in an apartment that doesn’t have adequate cooling throughout the whole apartment or one that does not allow you to use a window for a air conditioner,

A portable air cooler can be used as a way to cool down the apartment or as a supplement in the areas of the apartment that do not get cool.

4.Office Spaces

Mini air coolers have become very popular as a desktop solution to keep your personal space cool while you work at your desk.

5. Environmentally Conscious Persons

Unlike refrigerated ACS that can emit dangerous chemicals into the air because of the refrigerant that is used to absorb the heat,

Air coolers do not require anything besides a water hookup and a fan motor. There is nothing potentially dangerous or any chemicals that can be released from an air cooler.

6. Energy Saving

Unlike refrigerated air conditioning that can account for up to 5% tire Energy bill, swamp coolers require very little energy and you can expect your bill to be in the range of running a fan.

Evaporative Air Cooler
Disadvantages of an Air Cooler

1.  Limited Cooling

Evaporative coolers are limited and how much and how accurate they can cool a room.
The settings on a swamp cooler are limited to high, med, and low to control the fan speed and a switch to turn the water pump on.

There isn’t a thermostat to dial in a set temperature that you want the room to cool off to.

2. Do Not Work Well in Humid Climates.

Air coolers require dry air in order to get the best use out of them. Once the humidity reaches above 20 percent outside, it is just as effective to run a fan alone than to use a swamp cooler.

At that point, using a swamp cooler is only adding humidity upon humidity which will make the room feel sticky and “swampy”. Thus the name “swamp cooler”.

Unfortunately there are regions that are humid all year long and can’t really benefit from an evaporative cooler at all.

3. Don’t Cool Enough.

There was a time when swamp coolers ruled the world. People were used to warmer temperatures consistently. But now since Central heating and Air has come to the forefront, people are used to cooler temperatures coming from their air conditioner. And for a lot of people, evaporative cooling is just not cool enough anymore.

4.  Maintenance

Though not as much of an issue with large desert coolers that are designed to have the water ran directly to the machine,

When it comes to portable air coolers, they have to be filled with water in order to operate. That typically means carrying a bucket of water to the machine or running a garden hose from a faucet to the machine.

Water pad media must be kept fresh also in order to hold water.

5.  Bacteria

Evaporative coolers have the potential of standing water built into the design.

Since air coolers require water as part of the cooling process, they must be emptied anytime they are not in use to avoid the growth of bacteria.

Legionnaires disease is a deadly disease that has been traced back to bacteria growing in standing water primarily in commercial swamp coolers that had not been maintenance.

Standing water is also a nesting place for mosquitoes.

5.  Water Consumption

Though a great deal was made out of savings of you electricity by using a evaporative cooler of a refrigerated unit, little is mentioned about the amount of water that is used in an evaporative cooler.

For a portable air cooler, the amount of water used does is work mentioning. But for outdoor desert coolers, you will basically be using the same amount of water as you would to water the yard everyday.

6.  Noisy

Noise is always going to be an issue with evaporative cooling. The combination of a fan and a water pump create double the noise of just a fan. The water has its own sound compared to slurping or washing. Noisy nonetheless.


There was a time when evaporative cooling was the main form of air conditioning. It was much more common for someone to have a swamp cooler hanging out their window than to have the luxury of refrigerated central heat and air.

Though there are still certain areas that rely heavily on evaporative coolers, refrigerated air has become much more prevalent.

But does that mean that there is no place for evaporative cooling?

Not at all. There are many circumstances were air coolers make more sense than refrigerated coolers.

For instance there are many people who need a way to cool down a room or area who do not have access to any type of window to exhaust the heat of a standard refrigerated air unit.

This makes evaporative coolers a much more convenient way of cooling off multiple tops of rooms including garages, shops, apartments, etc.

The fact that air coolers are much cheaper to run and do not have any negative effect on the environment by the emissions of any type of chemicals is also a big plus and a central reason why some people choose evaporative cooling over refrigerated air.

But there are a drawbacks to air coolers too.

For one you can’t use an air cooler when the humidity is too high. But not only leaves out a huge amount of people who live in regions that are extra humid, it also excludes getting a very good result out of a evaporative cooler in the hot humid months of Summer when you need an AC the most.

Another drawback evaporative coolers have is the potential of standing water. Anytime and air cooler is not in use, it requires emptying the water so that there is no risk of developing mold and bacteria in the machine.

Legionnaires disease is a serious condition that can be traced back to origin, coming from commercial rooftop air coolers there were never maintenance and water allowed to stand and facilitate bacteria.

Stagnant water also invites mosquitoes to lay eggs in the water and become another issue that is absolutely not welcomed especially when you’re already dealing with humidity. 

Published by

Dennis Reed

Dennis Reed Owner and Author @ BreatheBetterAir.org