ECM: Space Heating & Cooling

H11. Install Swamp Coolers


Swamp coolers--also called direct evaporative coolers--have long been used to provide cooling in the hot, dry Southwest. They cost less than standard air conditioners and use 60-80 percent less electricity. The payback for swamp coolers is typically six months to five years compared to conventional air conditioning units, depending on the climate (E Source, 1995).

Image: Evaporative coolers use 60-80 percent less electricity than standard air conditioners.

Swamp coolers include a fan, a cellulose pad or filter, and a small water pump. The pump supplies water to the pad, which keeps it wet, and the fan blows hot, relatively dry air through the pad. The air is cooled as it passes through the pad and is then supplied to areas where cooling is desired. Because the process also increases the humidity of the air, swamp coolers are not appropriate for hot, humid climates where extra humidity would be unwelcome.


  • Single-family and multifamily buildings with old, inefficient cooling systems in warm, dry climates


  • Single-stage
  • Two-stage
  • Window units
  • Portable
  • Central


  • Proper maintenance is essential.
  • Swamp coolers are not appropriate for humid climates because they increase humidity.
  • When operating swamp coolers, a window should be cracked open to ensure proper operation and to prevent moisture buildup. The PHA should be sure to maintain building security.
  • Swamp coolers and air conditioners should never be used together to cool the same space at the same time.
  • Some utilities offer incentives for the purchase of evaporative coolers.


  • Swamp coolers use 60-80 percent less electricity than air conditioners.
  • Swamp coolers can have a payback as short as five years.


Energy Conservation for Housing – A Workbook, HUD, September 1998. Pages 7-90 through 7-93 addresses the installation of swamp coolers.

Consumer Guide to Home Energy Savings, American Council for an Energy Efficient Economy, 1999, ISBN 0-918249-38-4. Pages 93 and 94 address swamp (evaporative) coolers.

PATH Technology Inventory: Evaporative Coolers. Describes evaporative coolers, including selection, installation, operation, benefits, and costs. Includes links to additional information resources.