“Who better than Wal-Mart to stretch energy dollars farther than anyone ever has?” asks company Chief Executive Lee Scott in a speech given to employees last fall prior to a two-day meeting for analysts of the publicly traded retailer. “To help lower our energy bills and gas prices for years to come, the environment is begging for the Wal-Mart business model.”

Scott's speech announced company-wide initiatives that include a $500 million annual investment in environmentally efficient technologies and the creation of a new store prototype that would be as much as 30 percent more efficient within the next four years.

An experimental “green” test store opened last November in Aurora, Colo., to help the company figure out how to reach those efficiency goals in the most cost-effective way.

“We want to be on the cutting edge of green technology, not the bleeding edge,” says Don Moseley, Wal-Mart's director of experimental projects, during a media preview in November for the 206,000-sq.-ft. Colorado Supercenter. “Once we see what's working and what's not, we can make better decisions for other store designs.”

Energy is a huge chunk of operating costs for all business, Moseley notes during the media tour held a day before the store opened to the public. Also, there's no clear-cut way to “manage” escalating energy costs as there might be for other overhead. Moseley sums up the retailer's use of energy as a third each for lighting, cooling and heating. “That's about it in big buckets.”

The Aurora store is the second such green Supercenter to incorporate energy-efficient, environmentally friendly building materials and construction methods. The first, an identically sized big box in McKinney, Texas, opened last summer.

The Colorado store has no fewer than 50 methods to operate green, ranging from 500 tons of recycled concrete from Denver's old Stapleton Airport for the Superstore's foundation to solar panels on the roof.

Many of the green experiments are plain to see. For example, a 120-ft.-high wind turbine, with a rotor 46 ft. in diameter, is hard to miss. A saw-toothed roof with 15-ft.-tall windows captures as much sunlight as possible with the interior lighting automatically dimmed or turned off during the day. A sidewalk made from recycled tires winds its way through a parking lot designed to allow water to pass through and reduce rainfall runoff.

Company officials haven't left many experiments out. Bat nests outside, for example, will help control pests naturally. Expired produce from the Supercenter's grocery store will be sent to a local composter rather than a landfill.

For our industry, here are a few green plumbing and heating ideas incorporated into the Aurora store:

Light-Powered Infrared Sinks: You'd expect sensor-operated faucets in the Supercenter's bathrooms. But traditional sensors still need electricity to operate. Bradley Corp.'s ndite™ technology, however, uses the restroom's lighting system for power. The company's Express® SS and MG series of lavatory systems have a photovoltaic collector embedded on top of the sink that converts fluorescent light to charge a battery system.

Waste-Oil Boilers: In most Wal-Mart Supercenters, cooking oil used to fry foods is collected and recycled off- site. The same goes for engine oil drained at the store's auto shop.

There's nothing wasted with the waste oil generated at the Colorado store. Two waste oil boilers manufactured by EnergyLogic burn motor energy oil and cooking oil. According to Moseley, the boiler burning cooking oil reduces the Supercenter's use of natural gas by just under 22,000 thermal units; the boiler burning engine oil cuts natural gas use by 30,000 thermal units.

The store has a tank to store 2,000 gallons of waste oil for the boilers. Most Wal-Marts would have a tank for 800 gallons, if it were to be recycled. (Outside the heating season, the waste oil will be recycled as usual.)

Radiant, Snowmelt: In part, both waste oil boilers fire a radiant heating system that warms the floors of the entrance vestibule and cash register area. Radiant tubing was also installed in the floors and walls of the service pits in the auto shop.

Meanwhile, snowmelt takes care of the crosswalks, pharmacy drive-through, handicapped parking spaces and sidewalks.

The waste oil boilers aren't the only power source for the hydronics. The store also relies on a cogeneration plant consisting of six 60-kilowatt microturbines. The system delivers electricity and cooling to the building, but also recovers and re-uses waste heat, another source for the snowmelt system.

On a related heating note, the building's south wall is covered with perforated metal siding. Heat build-up from the sun warms the air in the wall cavity by 10 to 20 degrees depending upon the season and weather conditions.

The warm air rises to the top of the wall, and the store's ventilation system then draws that warmed air into the Supercenter.

“This 'natural' pre-heating system means less energy is needed to run the mechanical heating systems and less natural gas is needed to heat the store,” Moseley adds. In the summer, the wall acts as a solar shield, reducing solar heat gain and reducing cooling needs in the stockroom.

The Supercenter's ventilation system is made from fabric rather than sheet metal. The fabric has many small holes that distribute air flow throughout the entire length of the ductwork rather than a single register. What's more, the cloth ducts hang just 11 feet from the floor and use low velocity fans to distribute the air.

The supplied air mixes with the surrounding air and slowly falls to the floor where it is warmed by the occupants and other heat sources. The warm air then rises slowly through the store to be drawn out by the air conditioning units just below the roof.

“In the summer, the system expels hot air outside, helping to keep the interior of the store cool,” Moseley says. “In the winter, the system provides warmer air and reduces the store's total air flow rate to provide a more comfortable indoor temperature for customers and employees.”

Moseley explains the low-hanging ductwork will cut energy costs because it heats or cools only the lower 11 ft. of the store, unlike ceiling-mounted ventilation systems that need to push air at least twice as far. This method will save about 570,000 kilowatt hours of electricity annually.

Public Education: Three kiosks in the store will give consumers the chance to view a real-time Web site that will track the store's energy use. Customers will also notice informational spots painted on the store's floor that further explain the green techniques. One spot does highlight the radiant and snowmelt systems, plus a see-through wall by the cash registers lets people see some of the piping for the hydronics.

“Some of this stuff the customers can see and possibly say, 'I want that in my house,'” Moseley says.

The company will be monitoring another Supercenter in nearby Centenniel, Colo., for a baseline comparison. The company has already contracted with the federal government's National Renewable Energy Laboratory in Golden, Colo., to determine the effectiveness of the green technology.

Wal-Mart has a similar procedure to keep track of its Texas green outlet, too. The test stores aren't the only green initiative Wal-Mart has taken recently. The company's first Chicago store will be the first in the United States to sprout a green roof. The 67,000-sq.-ft. roof will be covered with cactus-like plants, designed to reduce rainfall runoff.

The company wouldn't say exactly how much more each green Super-center costs to build over a regular Wal-Mart. In Scott's speech last fall, he notes that the 10 percent gains in efficiency at the Texas green Supercenter certainly weren't enough to cover the cost building.

But he chalks it up to a learning experience and a long-term investment. With more than 5,500 stores selling a billion dollars worth of merchandise every day, the company has both the money to finance the experiments and the scale to make a little savings end up to some real money.

For example, Wal-Mart operates one of the business world's largest private fleet of trucks. Just improving fuel mileage by one mile per gallon would save Wal-Mart more than $52 million a year, Scott says.