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A 143-foot-tall wind turbine stands outside a Wal-Mart Supercenter in Aurora, Colo. Incongruous as it might seem, it’s also clearly a sign that something about this particular store is different -- from almost all of the Bentonville, Ark.-based retail giant’s nearly 2,000 other supercenters.
When you walk inside the store, however, you don't notice anything different. It's a traditional Wal-Mart Supercenter design: Measuring 206,000 square feet, the Aurora store features a full line of groceries, bakery goods, frozen foods, meat and dairy products, fresh produce, liquor, apparel and accessories, a lawn and garden center, health and beauty aids, consumer electronics, and a variety of branded quick-service restaurant options. In fact, it's the same "195 Prototype" (195,000 square feet of sales space) as its sister supercenter in the same city.
But if you look more closely, you might start noticing seemingly small differences -- perhaps some more natural sunlight here and there, a nice system of track lighting over the produce, a cooler that brightens when approached. Examined with a professional's eye, this store is, both literally and figuratively, quite illuminating.
Behind the scenes, experiments are underway, designed to push the green envelope and usher in a new era of environmental sustainability in operations, not just for Wal-Mart, but also for retailers -- indeed, for any kind of businesses -- worldwide.
"As one of the largest companies in the world, with an expanding global presence, environmental problems are our problems," Wal-Mart president and c.e.o. H. Lee Scott said during a speech he gave internally last year. "The supply of natural products (fish, food, water) can only be sustained if the ecosystems that provide them are sustained and protected.
"There are not two worlds out there, a Wal-Mart world and some other world," Scott continued in his speech. "I believe, in fact, that being a good steward of the environment and in our communities and being an efficient and profitable business are not mutually exclusive. In fact, they are one and the same."
Wal-Mart's environmental goals are to be supplied 100 percent by renewable energy, to create zero waste, and to sell products that sustain its resources and environment.
The retailer built a pair of experimental stores in Aurora, Colo. and McKinney, Texas so it could put these words into action. "You can see a lot of things on paper, but to really know if something's going to work or not, you have to see it in a real-life environment," says Andrew Ruben, v.p. of corporate strategy for Wal-Mart. "McKinney and Aurora give us the opportunity to experiment with dozens of technologies, one in a hot-weather and one in a cool-weather environment."
Wal-Mart contracted with the National Renewable Energy Lab of Golden, Colo. to provide monitoring, testing, and analysis on store systems and materials, based on national scientific measurements and standards, for a period of three years.
While experiments are running inside and outside of the store, a great number of them are on the food side of the store, as much of the equipment necessary for food storage, preparation, and cooking requires greater energy consumption than is needed on the general merchandise portion of the store. Therefore, the food side would benefit the most from the experiments, which are designed to make the most of the available energy.
Let there be light
Standing at the threshold of the food-retailing area, shoppers are exposed to several of these technologies in operation. The roof of the experimental Aurora store was modified to allow natural light into the main shopping areas. Built in what's referred to as a "sawtooth" design, the roof resembles a series of steps, with the vertical wall of each step lined with windows. Since the windows face toward the north, natural daylight can enter the store without the negative heat gain and UV effects of the sun. This natural daylight reduces the need for artificial lighting, and minimizes heat gain from fluorescent lighting in the store, which in turns means that it takes less energy to keep the store air conditioned.
The lighting system uses T5HO (high-output linear fluorescent) lamps, which use half of the energy of Wal-Mart's standard T8 lamps. The color -- referred to as color temperature -- of the lamps has been increased to 5,000K, to match the daylight entering the store. The lamps also allow customers to receive more light on their retinas, which, according to Wal-Mart, improves the shopper's ability to see merchandise in the store.
"The combination of the natural light and the new fluorescent lights lets us space the lights 17 feet apart," says Charlie Harris, store manager. "Spacing between rows of light fixtures in a typical supercenter of this size averages 13 feet. The increase in natural light results in fewer fixtures installed and less than half of the lamps normally required for a supercenter."
And just to make sure that power isn't wasted, light sensors constantly monitor light levels throughout the store, and either dim or turn off the lights in areas where they aren't needed.
Above the heads of the shoppers is the air distribution system. Called a "low-velocity thermal displacement ventilation system," it incorporates a fabric duct system that has many small holes that distribute an even airflow along the entire length of the duct, rather than directing flow from a single register mounted at the ceiling. The ducts are mounted 11 feet above the floor, and use low-velocity fans to distribute the supplied air, which is typically 62 degrees to 65 degrees Fahrenheit. The supplied air quickly mixes with the surrounding air and slowly falls to the floor level.
Wal-Mart estimates that this system will save about 570,000 kilowatt hours of electricity annually -- enough energy to supply the electricity needs of fifty-two single family homes, it says.
Meanwhile, below shoppers' feet, radiant floor heating uses hot water pumped through a series of tubes in the concrete floor to warm the floor and radiate heat into the store proper. The system is designed to help shoppers and associates feel more comfortable in specific areas of the store. In this supercenter, for example, the cash register area, entrance vestibules, open-top freezer case floors, and seasonal box are all warmed by radiant floor heating. The water in the system is heated by waste heat rejected from the refrigeration racks, and also heated by the waste oil boilers.
"It's another example of efficiency," says Harris. "Normally the heat would just dissipate from the top of the refrigeration racks. We put it to use."
This theme of efficiency runs throughout the store. Just past the threshold, Wal-Mart placed focused lighting just 12.5 feet above the fruits and vegetables, instead of the usual fluorescent lighting shining down from 18 feet; the difference means that less light is needed to effectively illuminate the produce.
"These lighting fixtures use 35-watt spotlight lamps, which consume less energy," notes Harris. "These lamps also have improved phosphors. Objects are rendered with truer colors, which enhances the color of the produce and makes the section more comfortable to shop, which is important as we continue to get into more organic offerings."
Along the wall opposite produce, occupying the right front corner of the store, are the deli and bakery, which offer prepared meats, fresh-baked breads and rolls, and heating fuel.
Yes, heating fuel. The store's heating system burns recovered cooking oil from the deli's fryers. The oil is collected, mixed with waste engine oil from the store's Tire and Lube Express, and burned in the waste-oil boiler. Typically these waste oils are recycled off-site. This waste-oil boiler reduces the supercenter's use of natural gas by just under 22,000 thermal units.
The produce storage area is typically guilty of wasting energy, as cold air escapes when clerks bring product from the refrigerated back room into the store's display areas. Not so in the experimental Aurora unit, however, which features a unique door that puts a lid on the refrigeration losses. "It rolls down after 20 seconds, unless someone passes underneath it," says Harris. "This keeps the escaping cold air down to a minimum."
Not all of the technology used in Aurora is for efficiency's sake; a healthy environment is another objective that store designers and engineers took into consideration. The wet-rack piping used to keep the produce moist and fresh, for example, is equipped with a battery coupling to seal the pipes by effectively melting them together; it eliminates the need to use glue or epoxies, which contain harmful ingredients.
Leading with LEDs
The crown jewel of the new technologies at Wal-Mart's experimental Aurora supercenter is the battery of LED lighting systems found in the dairy and frozen departments. The freezers and coolers for these departments are open in conventional supercenters, allowing cold air to escape into the store. This has two negative effects, according to Harris: First, the motors on the open coolers have to work hard to keep the products at optimum temperatures, and second, the cool air spilling into the aisle isn't comfortable for some shoppers.
"In this store we have doors on all the coolers and freezers to keep the air from escaping," says Harris. "In dairy we fill the shelves from the back, so the doors don't have to stay open. Plus we have radiant heat in the floor of this section. We often get comments from shoppers saying how surprised they are that the department's not cold."
In typical Wal-Mart stores the refrigeration systems pump high-pressure refrigerants (which are greenhouse gas producers) through copper piping to the display cases. This store, however, is employing secondary-refrigerant technology on the medium-temperature systems, such as the cases that display processed prepackaged meats, cheeses, and other dairy products. Propylene glycol (antifreeze), a secondary low-pressure refrigerant, is pumped to the display cases through ABS (acrylonitrile-butadiene-styrene) piping, which is simpler and less expensive to install than copper piping. Because the system is close-coupled, the use of a secondary refrigerant cuts the amount of high-pressure refrigerant in the system by 50 percent. It also reduces the chances of leaking high-pressure refrigerant to the atmosphere.
Because the coolers have doors, the cases need good lighting, and plenty of it. Wal-Mart worked with GE Consumer & Industrial Lighting to develop a system of LED lighting that would take the place of traditional fluorescent bulbs.
"They light the coolers brilliantly -- you can see every item on the shelves," observes Harris. "What's more, these LED lights will last 100,000 hours, which is a tremendous cost savings."
While the overall plan for the Aurora and McKinney experimental stores is to test the various technologies over three years, the new lighting system is a prime example of a new technology that Wal-Mart won't wait years to roll out.
"The LED lighting, which we also use in signage outside of the store, is a hands-down winner, and it's already being rolled forward," says Ruben. "The light quality is phenomenal, and the implications in terms of energy are great."
Indeed, Wal-Mart's next step in the strategy is to commercialize its breakthroughs in technology. "One of the really exciting points about the technology in Aurora is that it will allow us to bring sustainability to a mass market, allowing a broad range of people access to things that they have wanted but maybe didn't have access to before," notes Ruben.
"As we get into technologies like LED lighting, it's a great opportunity to work with it on the commercial aspect -- like in Aurora -- then be able to offer it to a small business member, potentially through our Sam's Club, and eventually be able to take that technology and bring it to the shelf as a sort of compact fluorescent technology [for consumer use]. Commercializing a technology will benefit multiple players and ultimately will increase the efficiency of energy usage in the world -- that's one of our goals."
Wal-Mart's scheme of turning an energy (and cost) savings solution into a product it can sell on the shelves sounds like a win for everybody. Just past the dairy, in the back of the experimental Aurora store, Wal-Mart takes this concept one step further by turning garbage into profits, via an organic trash disposal.
The store disposes all organic waste, including produce, meats, and paper, in an organic waste compactor, which is then hauled off to a company that turns it into mulch for the garden. When planting season comes around, Wal-Mart sells the mulch back to shoppers.
Behind the scenes
The experiments don't stop with the selling space, of course; they extend to the back storage rooms, the offices, and all the way out to the edge of the parking lot.
In the experimental Aurora supercenter, Solartube skylights provide natural daylight to the breakroom and layaway room, for example. They redirect sunlight down a highly reflective tubular shaft and through a diffuser located at the ceiling, helping to spread the sunlight uniformly around the space. "From inside the breakroom, you can't tell that they're skylights," says Harris.
Wal-Mart uses traditional light fixtures controlled by a dimming system to supplement the daylight in the room when necessary. And "necessary" is the operative word: When there's ample sunlight, employees can't turn on the lights.
Skylights also help light the receiving area of the store, using mirrored reflectors that track and channel the natural sunlight throughout the day. The active skylights provide natural lighting for longer periods of the day than a traditional passive skylight of equal size. While a certain amount of artificial lighting is still necessary for safety and liability reasons, the system reduces the amount that's needed.
Even the bathroom at the supercenter is green -- and it's not from mold. The waterless urinals in the men's restrooms, for example, are more sanitary than standard urinals. Besides eliminating odors, they substitute the water with a special environmentally friendly, biodegradable liquid, which saves one to three gallons of water with each flush.
Wal-Mart installs automatic infrared-controlled sinks in all of its stores. But at the experimental supercenter the sinks are photovoltaic-powered, using light collectors to generate the electricity that powers the infrared sensors that regulate water usage.
This and dozens more small technological touches make the supercenter a laboratory for efficient and Earth-friendly retail operations, which is why Wal-Mart is eager to spread the word by encouraging visitors -- even from competing companies. The more retailers know about the store, the more they may take interest in some of the experiments for their own operations. "We had Target in here not too long ago, and other retail chains and independents have also taken a tour of the store," notes Harris. "This is not something we're keeping to ourselves. We want everyone to know about it."
Plus the more people know about it, the better it is for Wal-Mart from a learning perspective, adds Ruben. "One of the things that we gained from these two stores, and really along this journey that we continue to be on, is that we see things we didn't know were possible," he says. "It's consistent with the business model of doing things in a smarter way, which ultimately benefits the customers and communities again. We've seen things that simply just make us a better company. One of our long-term goals is that we're supplied by 100 percent renewable energy. That's going to mean figuring out -- through experimentation and hard work and partnering with different companies -- it's going to require figuring ways to just use less energy and to find better sources of energy. The learnings from Aurora aren't just for Wal-Mart or for the U.S. We'll look for the application of these experiments globally."