Evaporative Coolers

How Effective Are They?

Learn about evaporative coolers and how effective they are in certain situations and climates as a low-cost cooling solution that actually works!

When you live in a hot, dry, arid climate where humidity is generally low, an energy-saving cooling alternative to air conditioning exists.

Instead of using kilowatts of electricity to run an AC unit, a high powered evaporative cooler can run at full power on just a few hundred watts.

Let's look at what evaporative coolers are and where they work best:

What is an Evaporative Cooler?

An evaporative cooler (often referred to as a "ventless air conditioner") is a compact cooling device that uses the cooling effect of evaporation to lower the ambient temperature in a space such as a bedroom or living room, workshop or garage.

The mechanics of the device are housed in a small rectangular box that resembles a portable air conditioner without the vent hose, but the resemblance ends there. Inside and evaporative cooler, there is no refrigeration mechanism, no refrigerant gas, no compressor and no heat exchange pipes.

Instead, it works by drawing moisture up from a reservoir in the base of the unit into a thin, porous membrane, then forcing air through the membrane using a simple fan to evaporate the moisture and expel the now chilled air into the room.

Its lack of refrigeration pathway means it uses very little electricity to operate, with only a fan and a control panel to power.

Some larger units also incorporate a pump to help draw moisture up into the membrane, but this is also low-powered.

Energy Saving Cooling

As evaporative coolers have so few energy-sapping mechanisms under the hood, the energy consumption is meager when compared to a similar output air conditioning unit.

Instead of consuming one to two kilowatts like ACs, most small to mid-sized evaporative coolers typically run on as little as 200 watts!

When you add up the energy consumption over the hot months, the saving on your electricity bill can be quite substantial.

The Downside to Evaporative Coolers

If these coolers are so amazing, how come everybody isn't using them and saving a small fortune on electricity bills?

While they work very well when the humidity is low and are capable of dropping the temperature by as much as 30 degrees, their effectiveness is diminished when the humidity level rises. In humidity levels above 50% they struggle to produce chilled air and at over 60% they only produce a blast of fanned air that isn't any cooler than the surrounding air.

Why is this?

Their effectiveness in producing chilled air is decided by how much moisture the air is able to absorb. When the air is dry, it can absorb a lot of moisture and so the chilling effect is very pronounced., It is much like the way that the evaporation of your perspiration keeps your skin cool when you encounter a breeze.

The breeze may not be any cooler than the ambient temperature, but because the moisture on your skin is evaporated by the breeze, it lowers the temperature of your skin. But when you are in a very humid place, the air is not able to absorb any more moisture and so the breeze does not feel cool even though you are perspiring.

The same effect is experienced by an evaporative cooler.

Dry air absorbs moisture and so the chilling effect of the evaporation is pronounced and the expelled air is cold. Humid air cannot absorb any more moisture because it is already saturated and so the sir expelled by the unit is not chilled.

Summary

In hot, dry climates, an evaporative cooler is an energy-saving cooling device that works to keep you cool when it's hot!

It is the perfect low-power cooler for all sizes of homes, garages and workshops as long as the humidity is low. Where humidity is higher, the cooling effect is not as apparent and in very high humidity, the effect is no better than that of a regular fan.

Before you choose to buy an evaporative cooler, be sure to contact your local weather station to find out what the humidity levels are in your area!