There are many reasons to use window evaporative coolers. They are generally installed in a window like an air conditioning unit but with many features that set these products apart from regular refrigeration air conditioning units. The evaporative air cooler uses hot air and water to dramatically lower your room temperature. They are significantly lower to operate electricity wise over regular air conditioners and they are cleaner to operate with the bonus of being better for the environment and creating cleaner air in your home. You can have a portable evaporative cooler, a window based unit that cools a room or a system installed in your home that cools your whole house. They also exist in commercial sizes as well.
There are great advantages to your electrical bill being reduced with a healthy flow of air and without damage to the ozone. This is a much more natural process of cooling your house and units even exist that have additional features of fighting dust and pollen. The hotter it is outside, the better the unit will work with evaporative technology.
There are varying materials inside the unit that can impact the performance of it such as materials that may or may not be susceptible to corrosion or rust. There are different types of absorbent pads with varying materials and levels of thickness, there are fans and blowers that will vary as well as a water reservoir that can determine how often you need to fill it. Some coolers can be fed water directly from your plumbing as well.