Does it surprise you when the area near a waterfall is cool even on a hot summer afternoon? This phenomenon is more commonly called evaporative cooling.
The air temperature around the waterfall reduces as the water evaporates.
Swamp coolers use a similar mechanism to cool homes.
Roof mounted swamp coolers absorb heat from the environment through evaporation of moisture.
The cooler absorbs water from air into specially designed pads which are soaked with water.
The air is then cooled by evaporating the water and circulated into the home or office space.
Swamp coolers are normally mounted on roof tops as it is easier for the blower to push air through a down-discharge cooler.
They use lesser electricity than the more conventional air conditioners.
Swamp coolers do not use refrigerants such as chlorofluorcarbons (CFCs) and hydrichlorofluorocarbons (HCFCs), which might cause harm to the ozone layer.
They do not require the windows and doors to be closed to keep the room cool.
It pumps in fresh air into the room and replaces most of the air that leaves the home.
Rooftop coolers do not take up unnecessary space on the floor.
However, there are some problems with a roof mounted cooler.
Like all coolers they tend to leak water over a period of time which deteriorates the framework of the cooler and the roof as well.
To maintain the cooler you will have to climb onto the roof.
Ground or wall mounted coolers face similar problems but are easier to handle at that level.