Some of those features include heat-soaking floors that will help cool the 210,000-square-foot store's interior and pipes that run through the concrete floors every six inches. The pipes carry cold water from indirect evaporative coolers on the roof and keep the floor temperature at 67 degrees to 68 degrees.

The cooling towers, which provide the cold water, run water through hundreds of black, engineered polymer tubes less than the diameter of a pencil, rather than more expensive copper tubing.

Water is sprayed on the outside of the polymer tubes, thus cooling the sealed water in the tubes. Typical swamp coolers, by comparison, cool air directly with water.

The indirect evaporative cooling system will provide 80 percent of the cooling at the store, said James McClendon, Wal-Mart's engineering director.

Skylights will provide most of the interior lighting during the day and will be supplemented by fluorescent lights that either dim or turn off when the sun is shining. Hot exhaust air from refrigerated food displays will be used to heat the store during winter and to heat water for the store year-round.

The rows of refrigerated food displays use light-emitting diodes lights that come on when someone walks by. LEDs convert electrical energy directly into light. LEDs are 70 percent more energy efficient than conventional fluorescent lights and emit less heat, making the refrigerator displays operate more efficiently.

The company plans to install LED lights for the parking lot by year's end.

In the open-air garden center, cashiers will sit under large ducts that carry cool air that otherwise would be pumped outside.

Wal-Mart says the energy-efficient systems are good for the environment because they reduce the need for power from polluting power plants. The company also says the systems will save it money.

"These are all great environmental wins, but they're business wins as well," McClendon said. "It's very exciting . (The Environmental Protection Agency) is very excited about it."

McClendon believes the new energy conservation system will pay for itself through lower power bills within four years.

The store, in the Arroyo Crossing Marketplace at the southwest corner of the Las Vegas Beltway and Rainbow Boulevard, is the first complete Wal-Mart Supercenter to contain these energy-conservation systems although the company tested the floor-cooling system in a portion of a store in Sacramento, Calif.

Wal-Mart technicians will be monitoring the cooling and lighting systems at the new store remotely through computers in Bentonville, Ark. The company will share data with the Department of Energy, the National Renewable Energy Lab in Denver and the University of California, Davis.

DOE spokesman Chris Powers said Wal-Mart has been holding high-level discussions with the government agency about the greening of the Wal-Mart stores.

An academic also praised the store's energy-saving features.

"We believe this is the most efficient cooling system implemented in a major retail facility," Richard Bourne, an associate of the Western Cooling Efficiency Center at the California university, said in a statement.

The energy system is specifically designed for hot dry, climates. Wal-Mart relies on other technologies for stores in areas with wetter climates.

If the Las Vegas store proves to be as energy-efficient as McClendon expects, other new Wal-Mart stores in the Southwest probably will use similar technologies.

Wal-Mart executives will be showing other retailers and technicians from around the country how the company designed the system during a tour today.

"It's one of our stated goals to share this information," McClendon said. "We're all in this together."

Wal-Mart has said it is the world's biggest private user of electricity and has huge potential to cut back on greenhouse gases from fossil fuels burned to create electricity. It aims to use technologies proven in Las Vegas and other future pilot stores to develop a prototype in 2009 for all new Supercenters that will be between 25 percent and 30 percent more energy efficient.

Contact reporter John G. Edwards at j edwards@reviewjournal.com or (702) 383-0420. The Associated Press contributed to this report.