This summary was prepared by Roof Science, which also developed the radiative cooling system for commercial buildings (UFTO Note July 11, 1997)

UFTO Note -Residential Indirect-Direct Evaporative Cooling (IDAC)

Natural Cooling for the Home
Davis Energy Group has developed an indirect-direct evaporative cooling system for residential use that can meet 100% of a home’s cooling requirements in dry climates, while consuming only 15% to 40% of the energy consumed by conventional systems. Unlike other indirect-direct evaporative cooling systems, IDAC (Indirect/Direct Air Conditioning) operates with only one variable speed motor and fan, making it more efficient. Other benefits include:

+ Measured EER of 26 to 56
+ Low installed cost
+ No CFCs
+ Low maintenance costs
+ Lower outside noise levels
+ Uses all fresh air
+ Low water consumption

IDAC can be installed without ducts. Room distribution can be provided by venting air through ceiling-mounted dampers into the attic. This approach keeps the attic cool. The system produces healthy household humidity in the 50% to 70% range. Refrigerated air conditioners dry air down to as low as 22% relative humidity, contributing to health problems. Standard evaporative coolers have the opposite problem, producing an uncomfortably high humidity.

Currently, there are approximately 30 IDAC units in operation. Partially funded by the California Energy Commission, the development of IDAC has been substantially completed, patents have issued, and the technology is ready for large scale application. IDAC is being manufactured by Cooltech Industries, Inc. of Sacramento.

The Market
An independent survey commissioned by the California Energy Commission indicates that there are approximately four million residential space coolers in California, with another seven million homes having no form of cooling at all. The market for IDAC includes existing homes not now conditioned, new construction, and the retrofit market. In addition, Utah, Nevada, Colorado, Arizona, New Mexico and West Texas have climates hospitable to IDAC. In particular, “Green” communities, multi-family housing and government housing facilities are preferred markets for IDAC. Due to its low power use, IDAC is also suitable for off-grid applications. Unit sales of 10,000 are projected for the year 2000, well under 2% of the residential space cooing market.

Competition
Only one company is known to have a similar product, Adobe Air, Inc. The Adobe “Master Cool” includes two fans and motors and therefore consumes considerably more energy. Other IDAC benefits versus Master Cool include full variable speed operation, intelligent control of water use, and a small 22”x23” footprint as opposed to Master Cool’s 42”x47” footprint. The Opportunity The company is projecting profitability within two to three years, and is seeking investment and business partners.

Contact
Mark Berman or Richard Bourne
Davis Energy Group, Davis CA
916-753-1100 mjberm@davisenergy.com