Evaporative cooling and air conditioning are similar in concept, but they work in very different ways. The former has been in use since ancients times in countries like Iran where the climate is hot and dry. It is a highly cost-effective way to chill the room air using the evaporative property of water. This method of room cooling is most suitable for hot and arid places like North Africa (which is made mostly of the Sahara Desert), the Middle East (which consists mostly of the Arabian Desert), southern Australia and parts of the western United States. The latter is a relatively new invention and works very well in any kind of climatic conditions, although there is no sense in using it in cold places.

It is time to switch on the air conditioner when the heat of the summer raises the mercury level. When looking for a new air conditioner or replacing an old one, there is essentially one thing you have to consider: the size of the place to be cooled. The general rule of thumb is that the bigger the area to be cooled, the more powerful the air conditioner.

Evaporative coolers are widely used in the western United States, southern Australia and Iran, where the climate is hot and air is dry. Also known as swamp coolers in the USA, they are cheaper than air conditioners and require less energy to operate. Although they are becoming popular in recent years, evaporative cooling has existed for as long as anyone can remember. A form of evaporative cooling was used extensively in the ancient Persian Empire. In those days, the Persians used to have air shafts on the roof of their house to let air into the house from outside, pass the same through a water container and send the cooled air into the house. Modern day Iranians use the same technology in its more efficient form extensively to cool their houses.