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Walmart has installed new energy-saving equipment on the rooftops of 14 stores in northern and central California.
Called DualCool, the units are retrofittable systems by Vacaville, Calif.-based Integrated Comfort Inc. that improve the efficiency of rooftop cooling units (RTU's) in dry climates by using a direct evaporative process to pre-cool outdoor air entering the condenser coil, and an indirect process (no moisture added) to pre-cool ventilation air entering the building. On retail facilities in hot dry climates, DualCool typically reduces annual cooling energy use and peak electrical demand by 25 to 40 percent, according to the company.
"We are focused on leading the industry with implementation of cost-effective technologies that improve efficiency and move us toward a more sustainable future," says Jim McClendon, Walmart director of engineering. "We have been evaluating various evaporative pre-cooling products, and our major criteria are performance, durability, and favorable economics."
This 2011 installation program resulted from a partnering effort of three affiliate members of the UC Davis Western Cooling Efficiency Center (WCEC): Pacific Gas and Electric Company (PG&E), Walmart and ICI. UC Davis launched the WCEC in 2007 to accelerate the implementation of proven cooling technologies that take advantage of the unique characteristics of dry climates typical of the western U.S.
Walmart began testing DualCool on stores in California and Arizona in 2008. ICI introduced its "Generation 2" DualCool version in 2010. Prototypes of this higher-performance, lower-priced DualCool line were monitored by the WCEC in 2010, leading to this year's Walmart demonstration program supported by PG&E.
The 2011 installations were supported by PG&E as a potential element of its Emerging Technologies program. Beutler Heating and Air of Sacramento, another WCEC Affiliate Member, installed the 115 DualCool units under a subcontract with ICI. The 14 stores ranged from Oroville in the north to Fresno in the south.