Tuesday, May 29, 2012

Don't Worry About Swamp Cooler Water Consumption

People sometimes worry about the water consumption of an evaporative cooler.   I found this information in an NREL report:

"on a Btu-of-cooling-per-kWh-of-electricity basis, the best evaporative cooling systems are on the order of five times more efficient than SEER 13 central air conditioning (CAC) systems and demand is less by a factor of four or more. Further, additional water use at the site (home) amounts to only about 3 percent of the water use of an average residential customer."

So don't let water costs drive you away from swamp coolers in Denver.

However, if you are building a new, smallish, superinsulated low energy home, you are better off going with a mini-PTHP for heating and cooling.  A swamp cooler requires more maintenance and seasonal mode changeover, which is awkward due to seasonal overlaps like "Indian Summer".


  1. Any chance you have a link or the name of the cited NREL report?

  2. "Water. Evaporative coolers use water, but well-designed, modern coolers use a batch flushing process to clean the sump rather than a continuous bleeding technique. The result is better cleaning and substantially lower water use. Modern coolers in efficient homes in the Southwest use an average of 5,750 gallons of water per year in the Southwest, about 3.3% of average annual residential water use. This amount of water costs $5 to $20 per cooling season. However, since evaporative coolers save on the order of 3,600 kWh per year, about 1,810 gallons of water are saved at the power station on average in the Southwest, for a net water use of evaporative cooling of 3,940 gallons. (State-by-state details are shown in “New Evaporative Cooling Systems: An Emerging Solution for Homes in Hot Dry Climates with Modest Cooling Loads.”)"
    From: http://www.swenergy.org/publications/documents/Evaporative_Cooling_Policy_Options.pdf

  3. Follow the above mentioned simple maintenance tips and you can prolong the life of your HVAC equipment and improve the air quality inside of your home. Regular maintenance done by professionals can be used to detect small problems before they become big problems and costly HVAC appliance damage.
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