Under the right conditions, swamp coolers look like they have lots of benefits. They're cheap to build and install. The only materials it takes to make them are a blower fan, a pump, a pad (either synthetic or made of wood shavings), some water and a box (usually made of sheet metal). Pumps and fans are widely available. The rest can be turned out in a local shop just about anywhere. In 1998, according to the Evaporative Cooling Institute, there were between 300 and 400 manufacturers in New Delhi turning out one million coolers a year, the smallest of which cost $35 USD [source: New Mexico State University]. The National Association of Home Builders (NAHB) estimates that an evaporative cooler, installed, costs between $700 and $1,000, compared to several thousand dollars for a central air conditioner [source: Toolbase].
The monthly operating costs are considerably lower as well -- about one third that of a standard air conditioner, depending on the costs of electricity and water, according to the NAHB. The savings is in the electricity -- a standard air conditioner takes as much as four times the energy to run than a comparable swamp cooler. That translates to savings on your energy bill, but also in the environment. The electricity saved by those 20 million evaporative coolers in 1998 meant power plants saved 60 million barrels of oil and produced 27 billion fewer pounds of carbon dioxide.
Swamp coolers have a further environmental benefit, since standard air conditioners have long relied on ozone-depleting chemicals to provide their cooling power. The use of CFCs (chlorofluorocarbons) has been discontinued in developed nations since 1996 by international treaty. The replacement byproducts, HCFCs (hydrochlorofluorocarbons), aren't as bad, but they still have some negative effects, and their use in new equipment will end in 2010. The Environmental Protection Agency (EPA) has compiled a list of approved substitutes for both CFCs and HCFCs in air conditioning systems [source: Environmental Protection Agency]. Also on the list: evaporative coolers.