How Effective are Evaporative Coolers?

With economy at the forefront of the decision as to which cooling device to buy, how effective are evaporative coolers for keeping you cool during the heat of summer?

The traditional air conditioners, which include central air, mini split, portable and window units, are excellent tools to remove heat from a space.

Air conditioning is a great way to cool down your home, but it can also be very energy-intensive, meaning that it is costly and can lead to a self-fulfilling prophecy.

evaporative coolerGlobal warming means that we need to use more AC, which in turn costs more money and uses more energy.

We don't even need to mention the complicated effects of chemical refrigerants on our atmosphere.

What is Evaporative Cooling?

Evaporative cooling, a low-energy alternative to refrigerants, uses less energy and requires much less power.

There are many different ways to make the most of natural evaporative cooling processes. But one solution is to either build or purchase an evaporative chiller.

The swamp cooler, or ventless air conditioner is just another name for an evaporative cooler. This device uses a fan and wick to cool the room's air.

People remember those spray bottles with the fan on the top that they used to spray water into their faces as they waited in line to ride the roller coaster in the dead summer. It's basically the same, just on a bigger scale.

Do Evaporative Coolers Really Work?

You may begin to wonder if evaporative (swamp) coolers really work to keep you cool and if so, why isn't everyone using them?

Evaporative cooling is loosely based upon the human method of perspiring. You might have heard about and experienced it at times!

Our bodies naturally cool themselves down by releasing moisture through the skin. The moisture is picked up by pleasant breezes and the skin is brought back to a more comfortable temperature level.

It's possible to achieve the same effect by running a sprinkler. It's basically what a swamp cooler does to the air in your room. We found that the starting environmental conditions can make or break this cooler.

Cooling Ability

Recent site tests show that the swamps cool the room slowly, but surely. However, these coolers do not do quite as well as similar size regular and self evaporating portable air conditioners.

For every 1°F drop in temperature that a swamp cooler makes, the humidity rises by about 2%-3%. Technically, this is logical. After all, that's what they were designed to do.

Portable and window air conditioners, on the other hand, actually de-humidify an area as part their cooling process. This is what is observed in tests (it's also the reason why that second-floor window AC is always dripping).

Both methods are effective in keeping you cool. They just have different ways to do it.


In a test environment in the Northeast on a day when humidity outside was at 50%, a swamp cooler is effectively set up for failure. With the air so saturated, the machines can't do anything but over-humidify and make the room feel damp but not cooler.

It is similar to the feeling you get if your sweat doesn't evaporate on really hot, humid days.

A fan can make a big difference in humidifying the air. According to the US Department of Energy, an evaporative cooler can effectively reduce the ambient temperature of 5 to 15 degrees. But even the DOE quickly clarifies that this process is only applicable in areas of low humidity.


While they are very desirable because of their low energy consumption, swamp cooler won't work well in areas with high humidity.

If you live in an arid, warm climate, especially in the western US it can be a cost-effective and reliable way to bring some much needed chill to your hot, dry summer.

However, if you live in a humid climate, your best choice is to get an air conditioning unit to suit the size of the space you need to cool. It will cost more to run, but it will also keep you cool!