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Climates suitable for evaporative cooling

In Australia

In Australia evaporative coolers generally work along the Southern Coastal Areas plus most of Inland Australia. Theoretically Sydney should be a suitable climate as well, however they have not as yet been accepted there. I believe that part of the reason is due to lack of knowledge of how to get the best out of an evaporative cooler. In addition there are usually a small number of days each year in Sydney when it is both hot and humid and the cooler is then only providing relief. Finally I have noticed that people's expectations in capital cities are generally greater than in country towns, even if the country town is hotter or more humid.

The rest of the world

Generally dry climates and dry summer climates are suitable. Tropical areas are not suitable. Subtropical areas are not generally suitable but may suit some applications. Refer to theevaporative cooling world map

Why is this so?

Evaporative cooling is very successful if properly designed up to a Wet bulb temperature of 22 degrees Celsius (71.6F). It can also be used in more humid areas (up to 24 C (75.2F) wet bulb or even 25 C (77F) wet bulb, provided it is not as humid most of the time), however the number of days where it is uncomfortable is increased.

Wet bulb temperatures are not as readily available as relative humidity measurements, however relative humidity is meaningless when trying to decide whether an area is suitable for evaporative cooling.

Wet bulb temperature

Wet bulb temperature is measured using a thermometer with a wet sleeve or wick around it. Air is blown over the thermometer and the water on the sleeve evaporates and cools the thermometer, so that it is reading less than the temperature read by a normal (dry) thermometer. The temperature it reads is called the wet bulb temperature. An ideal evaporative cooler would cool to this temperature. Naturally a real cooler doesn't get as cold, but it gives an indication of the sort of temperatures you can get. It is important to note that if you are in a humid area it is necessary to make sure you have good air motion in the room as this helps the body cool.

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