Evaporative cooling has made a major leap forward with the introduction of a two-stage model specially designed for residential applications. Called Smart Cool, this unit can match the cooling capacity of a three-ton air conditioner (in a well-insulated house), but uses only 20 percent of the energy. A typical three-ton refrigerant air conditioner has an Energy Efficiency Ratio (EER) of 10-12, while the Smart Cool boasts an EER ranging from 26 to 56. And, it has a peak power demand of only 400 Watts compared to about 3,000W for a three-ton air conditioner. Smart Cool uses only fresh air and water, no CFCs, HCFCs or refrigerants of any kind.

Instead of recirculating air within the house, the unit provides 100-percent, filtered outdoor air. In most installations, air is delivered directly through the wall, or it can be ducted to one or two central locations. Air exits the home through vents to the attic, which cools the attic and further reduces heat gain.

Smart Cool is a two-stage evaporative cooler, also called an"indirect/direct" cooler. In the first stage, incoming air passes through a water-filled heat exchanger that cools without adding moisture. In the second stage, air passes through a water-soaked pad where the temperature drops more and the air picks up water, which increases the humidity. Most residential evaporative coolers use only the direct cooling method, which can keep the relative humidity around 70 percent.

Compared to typical residential coolers, the two-stage approach increases the overall cooling capacity and keeps the relative humidity between 50 and 65 percent. Smart Cool is designed to operate with wet bulb temperatures of 70 degrees F. Smart Cool also can be connected to a hydronic heating system to add cooling capabilities to radiant floor heating systems.

Smart Cool can be mounted on an outside wall, on the ground or in the attic. The unit uses one variable speed blower and automatically purges the water reservoir to keep it clean.

The device was designed by Davis Energy Group with funding from the California Energy Commission, manufactured by CoolTech Industries and sold by Hydronic Specialties Company.

Update: After some initial test installations, SmartCool has returned to product development. A small number of units may be available. Contact Davis Energy Group for more information.