Although swamp coolers and air conditioners were invented to turn hot air into cold, the science behind each method is quite different.

What is a swamp cooler?

It’s just another name for an evaporative cooler. Water is used to moisten the absorbent pads around the sides of the cooler. A fan or “squirrel cage” draws outside air through the pads and the air cools as the water in the pads evaporates. The main benefit of this type of cooler is that you only need to turn on a water pump and fan to blow air through the pads.

They typically use three to 10 gallons of water per day. That’s equivalent to a few flushes from the toilet or, on the higher end, a short shower.

Unless the relative humidity is less than about 30%, swamp coolers are not very effective. They work well in Southwest, West Texas, and parts of Idaho, Washington, Colorado, Wyoming, and Montana. In those areas, you should be able to achieve a 20 degree difference between the outside and the inside.

Also, for a swamp cooler to remain effective, it must draw in as much of the air as it takes in. This means keeping a window open. If you don’t, the humidity will increase and so will the temperature of the air coming out of the cooler.

Air conditioning, on the other hand, is popular because it will reliably dehumidify and cool the air no matter where you live. This is how an air conditioner works:

The compressor compresses the cold freon gas, causing it to turn into hot freon gas under high pressure. This hot gas passes through a set of coils so that it can dissipate its heat and condenses into a liquid.

The freon liquid passes through an expansion valve and, in the process, evaporates to become cold, low-pressure freon gas. This cold gas passes through a set of coils that allow the gas to absorb heat and cool the air inside.

Mixed with the freon is a small amount of light oil that lubricates the compressor.

Swamp cooler vs air conditioner: which one is cheaper to operate?

In our friendly contest, the swamp cooler wins easily. For similarly sized units, even an Energy Star rated air conditioner uses 4 to 5 times the energy needed to run a swamp cooler.

The difference is the amount of energy required to power an air conditioning compressor versus the electric motors used in a swamp cooler.

What is better for the outside environment?

Unless you believe the soon-to-be-outlawed R-22 refrigerant is a good thing leaking into the atmosphere from your air conditioner, the swamp cooler wins again. The swamp cooler maintains a green profile by mimicking nature’s cooling way.

How an air conditioner or swamp cooler affects the indoor environment of your home is determined by the way the air circulates. Although an air conditioner recirculates the same air, this is useful for controlling allergens like dust and pollen.

Since an open window is necessary when running a swamp cooler, it will let in whatever the air conditioner lets through.

Swamp Cooler vs Air Conditioner: Which One Wins?

I think swamp coolers are a good option, as they are relatively less expensive and much cheaper to operate than air conditioning, as long as you live in Phoenix, Arizona. But if you call Little Rock, Arkansas home, no one is going to dissuade you from your air conditioning.