What would happen if you took almost every available energy-efficiency system and installed them in one store? How much energy would that store need to run? How much would it save?
Wal-Mart Stores is about to find out.
Known for its mastery of supply chain efficiencies, Bentonville, Ark.-based Wal-Mart has turned its talents to in-store energy efficiency with the opening last month of an experimental, 206,000-square-foot supercenter in McKinney, Texas, just north of Dallas.
At its new store, Wal-Mart intends to test the limits -- both for itself and the retail industry at large -- of what can be done to save energy in a mass-market retail environment. "This store will contain many of the best resource conservation technologies currently available," said Mike Duke, executive vice president, Wal-Mart, and president of the company's U.S. division, in a statement. Technology vendors interviewed by SN noted that few if any stores combined as much energy-related technology in one location.
The store's list of energy systems reads like a laboratory designed by the Environmental Protection Agency. Outside the store are two energy-producing wind turbines, a rainwater harvesting pond and treatment system, solar-powered traffic signs and a windmill. The store itself features roof-mounted solar panels, natural light sensors, heat-reducing reflective ceramic paint and radiant floor heating. All told, 26 energy-related "experiments" will take place at the store.
The opening of the new McKinney supercenter takes place as Wal-Mart continues a year-long defense of its corporate and labor management practices against a torrent of criticism from labor and activist groups. Even the company's environmental impact has come under attack by the Institute for Local Self-Reliance, Washington, which cited the 75,000 acres of land that Wal-Mart's stores and parking lots occupy in the U.S., including 200 empty stores that generate pollutant runoff. The group also contends that Wal-Mart is a major cause of the dramatic increase in drive time incurred for shopping trips.
Mindful of the need to present itself as a good corporate citizen, Wal-Mart plans to share its findings about energy conservation at the McKinney supercenter with the retail industry, general public and government agencies, as well as apply them to future Wal-Mart facilities, Duke said. "Sharing the results of the store's experiments with the rest of the retail and development industry could turn low-volume, rare technologies into industry standards," Wal-Mart said in a statement. The Institute for Self-Reliance, however, regards the McKinney store as a means for only "very modest improvements in energy consumption."
To determine just how significant the store's efficiency will be, information related to the store's experiments will be collected, monitored and compared to that of a traditional, brand-new Wal-Mart Supercenter, also located in McKinney. "The [other] site will serve as a baseline for comparison with the experimental store," said Jim McClendon, mechanical engineering manager, Wal-Mart. "They share similar demographics."
The experiments will be monitored remotely by third-party consultant Oak Ridge National Laboratory, Oak Ridge, Tenn., over a three-year period. The environmentally friendly store is projected to be between 35% to 50% more energy efficient than its cross-town counterpart, according to Jeffrey Christian, building technologies center director, engineering science and technology division, Oak Ridge National. He is charged with analyzing the results of the experiments -- both individually and collectively.
"This is an experimental store, so results will determine what can be improved upon and how we will move forward," McClendon said. This fall, Wal-Mart will open a similar experimental store with many of the same experiments, as well as additional ones, in Aurora, Colo. Although the Aurora store is being constructed in a colder climate, the variance of experimental results is not expected to be too dramatic. "It's amazing how climate insensitive stores this large are," Christian said.
Unusual Parking Lot
Shoppers visiting the environmentally oriented McKinney supercenter will notice two three-blade wind turbines, provided by the Bergey Windpower Company, Norman, Okla., sitting atop poles in the parking lot. The amount of energy produced by the wind turbines is dependent upon wind speed. The average wind speed in McKinney is 10 mph, and the large turbine is designed to operate in wind speeds as low as 4.5 mph, according to Wal-Mart.
Wind turbines are sometimes used to create energy for small businesses and residential properties and by "wind farmers" who sell the energy to their local utility. "This is the first use of [turbines] by a commercial operation of this size," said Mike Bergey, president, Bergey Windpower. Wal-Mart will use all of the energy it produces. "[Wal-Mart] sells many things, but energy [will not be] one of them," said Tara Stewart, spokeswoman, Wal-Mart.
Energy created by the larger, 50-kilowatt turbine, which sits atop a 120-foot-high poll, will be used to supplement energy needs inside the store. The energy produced by the larger turbine will reduce the electricity consumption by approximately 5%, according to Wal-Mart. The smaller, 1-kilowatt turbine, equipped with an energy-storing battery, is dedicated to lighting the Wal-Mart "monument" sign near the parking lot entrance.
As they turn, wind turbines create torque, which drives an electrical generator. Power processor electronics, mounted at the base of the tower, convert the wind power to utility-grade electricity. The power travels underground and is fed into the store's main circuit, where it replaces energy that would have been provided by the local utility company.
According to Wal-Mart, it's not only helping to conserve energy resources by creating power this way, but it's also helping to reduce the amount of greenhouse gas emissions created by the commercial production of electricity.
Also outside the store, a rainwater harvesting and treatment system captures water from the roof and a portion of the parking lot for irrigating plants and trees that shade the parking lot. The system features a windmill used to circulate water, purified by plant material, between holding ponds. Condensation from the store's air-conditioning system, which is usually discarded, is also collected and stored in the ponds and used for irrigating purposes.
Each plant has its own underground irrigation spout from which water drips "to minimize evaporation loss," McClendon said. Moreover, the irrigation system is demand-based and takes factors including recent rainfall into consideration, he said. Wal-Mart projects that the system will provide 95% of the water needed for irrigation at the site.
"For a large retailer an [irrigation] system like this is very unusual," said John Murphy, landscape architect, Land Resource Design, Tyler, Texas. "Rather than take up the land to do this, [most retailers would] probably just sell it."
Let There Be Light
The energy needs of the McKinney store are also supplemented by solar power collected by the supercenter's 7,500 square feet of photovoltaic solar panels, provided by RWE Schott Solar, Billerica, Mass., and Solar Integrated Technologies, Los Angeles. The panels, which convert light energy into electric energy, are located in several places, including the supercenter's Garden Center canopy, the roof of its Tire and Lube Express center, the front entry facade of the store, and the roof of entry vestibules.
The converted solar energy can be used immediately, stored for future use or placed on a power grid. "Solar power is inverted and fed directly into the main [energy] distribution of the store," Wal-Mart spokeswoman Stewart said. The panels on Wal-Mart's Garden Center canopy alone are estimated to generate 14,585 kilowatt hours annually, enough to power 486 single-family homes for one day and reduce greenhouse emissions by more than 22,000 pounds a year, according to Wal-Mart. In total, 3% of the store's energy needs can be provided by solar energy, Stewart said. Retailers such as Albertsons and Safeway are also harvesting power through solar panels, said Eric Linzmeyer, vice president global sales, Solar Integrated Technologies.
Many of the store's solar panels as well as skylights allow natural light to pass into the store, McClendon said. "On a bright day the whole store can be lit by solar power," he said. The supercenter's demand-based lighting system features sensors that monitor the amount of sunlight entering the store through skylights. These sensors automatically adjust the brightness of fluorescent lamps based on the availability of natural light.
The store's lighting system also uses small, 5/8-inch T5HO (high-output linear fluorescent) lamps. These lamps produce as much light as two T8 lamps, which are used in other Wal-Mart stores, according to the retailer. Though more intense than other lamps, these need to be changed fewer times. At night, the store's artificial light levels are dimmed to reduce energy consumption. A slight variation of these lamps is used by Wild Oats in its Aurora, Ill., store, a spokesperson from Malmstrom White Company, Little Rock, Ark., said.
All told, lighting savings at the experimental McKinney store are projected to approach 300,000 kilowatt hours per year. The typical Wal-Mart supercenter has historically been used approximately 1.5 million kilowatt hours annually.
Energy-conservative light sources, called light emitting diodes (LED), have also been installed in the experimental store's refrigerated cases. Typically these cases are equipped with fluorescent strip fixtures. "This is the first time [Wal-Mart] has used LED in a large-scale rollout," McClendon said. LED lights have a longer lifespan, produce less heat and use about 50% less energy than typical grocery case lighting, he said.
Fabric, Not Metal
In a typical Wal-Mart supercenter in southern states, cool and warm air is distributed through metal ducts mounted near the ceiling. At the experimental store, Wal-Mart uses "fabric ducts," made out of cloth rather than metal, with many small holes to distribute an even air flow. Unlike the ducts typically used in supercenters, these ducts are mounted lower to the ground -- at 11 feet above the floor -- so they can effectively cool the space closer to shoppers.
"Metal ducts are heavy and labor-intensive to install," said Nick Paschke, director of marketing, Milwaukee-based Duct Sox, manufacturer of the fabric ducts that Wal-Mart uses. "Fabric ducts are more flexible, easier to install and cheaper to ship." Since the fabric ducts are also machine-washable, they are also easier to maintain, Paschke said. Although the experimental store is the first Wal-Mart Supercenter to use fabric ducts, about 20 to 25 Sam's Clubs have installed them, according to Paschke, who said Target, Tops, Giant, Weis Markets and Meijer have also installed these ducts.
In a cooling scenario, after cool air leaves the fabric ducts, it's warmed by customers and other heat sources and rises above the fabric ducts to an area that doesn't need to be cooled. The system saves about 700,000 kilowatt hours of electricity per year, enough to power about 70 single-family homes for a year, according to Wal-Mart.
Customer comfort and conservation also led to the installation of the retailer's radiant floor heating system. It's installed under the floor in areas that sometimes become too chilly for shoppers, including the frozen foods section and the areas near entrances. The system uses hot water to conduct heat through tubes that warm the floor. "The radiant floor heating system's pipes are plastic and were woven into the floor before the cement was laid," Christian said. "The system's temperature is controlled by thermostats."
In addition to water conservation, the experimental store has found practical uses for materials often considered waste. Motor oil from the store's Tire and Lube Express and used cooking oil from the deli are collected and saved for a bio-fuel boiler that generates heat on site to warm the building. The natural gas saves more than 30,000 therms of heat energy. That is enough to heat and provide hot water for 26 single-family homes in McKinney for a year, according to Wal-Mart.
In addition, waste heat from the store's refrigeration system is captured and redirected to heat the radiant floor heating system and the water used in the restroom's sinks. Parts of the sidewalk at the store have even been created from recycled rubber tires.
