Living Green

Wal-Mart cuts another price -- of its own energy use

LAS VEGAS — The new Wal-Mart Supercenter here is like those in any other part of the country. Except when the monthly power bill arrives.

Despite its location in the middle of the desert, where 100-degree days are the norm, the power bills at the store here about half as much as those at similar-sized Wal-Marts in the region.

It's "the most efficient store ... in the United States," said Charles Zimmerman, Wal-Mart's vice president for prototypical design.

A special evaporative cooling system — akin to an old-time swamp cooler — pushes air-chilled water through a mesh of tiny pipes beneath the floor of the store, all but eliminating the need for traditional air conditioning.

More than 200 skylights provide almost all the lighting the store needs on bright days. The skylights are part of a "daylight harvesting system" that automatically dims or brightens electric overhead lights as needed.

Display cases for food are equipped with LED lights that turn on only when a customer trips a motion sensor. Waste heat from equipment is used to warm the water in the bathrooms and elsewhere. Waste cooling from freezer chests is all that's needed to keep some parts of the store completely cool.

It's definitely the most energy-efficient store Wal-Mart has ever built. It's probably the most efficient that any retailer has ever built anywhere.

The store, developed with lessons Wal-Mart learned at experimental Supercenter stores it built in McKinney, Texas and Aurora, Colo., is attracting a lot of attention.

Since opening in March, store manager Lynne Leckie has given more than 20 tours, for everyone from executives of competing retailers to the U.S. Department of Energy to a busload of foreign shopping center executives that showed up at the entrance one day.

"You don't really appreciate everything we're doing here until others come see it and tell you what they think about it," Leckie said.

Some of the innovations were adapted from other Wal-Marts and simply improved and expanded for the Las Vegas store. Others, such as the evaporative cooling and "radiant" floor system, are new.

The store is just one example of how the world's biggest retailer is also becoming one of the world's most energy-efficient businesses — not necessarily because it's the right thing to do, but because it saves money and boosts profits.

Ever since CEO Lee Scott issued an ultimatum in 2005 to make Wal-Mart a more sustainable business — environmentally and otherwise — the retailer has been on a tear to cut energy costs.

It has pledged to invest $500 million a year in new efficiency technologies and eliminate 30 percent of the energy used across all of its thousands of stores.

It is working on ways to increase its truck efficiency by 25 percent, which alone could save the company more than $310 million a year by 2015.

It is reducing packaging anyplace it can, which saves millions in freight shipping costs and also saves trees. By eliminating some packaging materials on one of its private-label toy lines, for instance, Wal-Mart estimates it could save 3,800 trees, 1,000 barrels of oil and $2.4 million in freight costs.

And that's just the beginning.

"One thing (CEO Scott) likes to say is that we haven't even gotten to the low-hanging fruit yet," Rand Waddoups, Wal-Mart's senior director of corporate strategy and sustainability, said in an interview earlier this year. "We're still too busy picking the $1,000 bills off the ground right now."

Critics say Wal-Mart could and should do much more.

Activist group Wal-Mart Watch points out that the energy needed to fuel the retailer's growth far outweighs the energy it is saving.

Even if Wal-Mart's supercenters are more efficient, the group claims, they're so big that they still require dramatically more electricity to operate than smaller community stores. At the same time, according to Wal-Mart Watch, stores are typically built in locations that require customers to drive farther from their homes.

Even so, Wal-Mart's efficiency and environmental efforts are winning accolades from other groups who in the past have criticized the company.

"I love what they're doing, because they're game-changers," said Kert Davies, research director for Greenpeace.

By pioneering energy saving technologies and rolling them out among numerous stores, Wal-Mart is helping bring down prices for the new systems and creating a bigger market for them, he said.

That's what happened with the mesh-like cooling system Wal-Mart installed in the concrete floor of the Las Vegas store.

Such systems have been used before, but traditionally have been too expensive for use in big stores like Wal-Mart's.

But working closely with suppliers, Wal-Mart helped design a new roll-out radiant flooring mesh system that cut the cost from about $8 a square foot to less than $2 a square foot, according to Jim McClendon, Wal-Mart's chief mechanical engineer.

Though some of the advancements at the Las Vegas store are designed specifically for dry desert conditions, Wal-Mart plans to apply whatever it learns at the store wherever possible.

Already, it is considering using radiant floor systems for heating its new stores in colder climates.

And while the evaporative cooling system might not work as well in the humid South, engineers are working on ways to improve dehumidification systems to cut air conditioning costs in places like Georgia, Florida and Texas.

Just as important, other retailers are watching Wal-Mart closely, and are working on ways to make their own stores more energy efficient, McClendon said.

"That's what's really exciting — we're watching the entire industry start to change," said McClendon.

MAKING IT GREEN

Here's how Wal-Mart made its new Las Vegas store use at least 40 percent less energy than a typical store of similar size:

EVAPORATOR SYSTEM

On the roof, water is cooled by the air as it travels through tubes in a series of evaporative cooling towers. The chilled water is sent through a series of pipes throughout the store, beginning with a refrigeration system attached to grocery and freezer cases.

RADIANT FLOOR

Water from the evaporator system also goes through a mesh-like series of pipes embedded in the concrete floor of the store, providing almost all of the store's cooling needs except on the hottest days.

WASTE HEAT/COOLING

Another system captures the waste heat from refrigerators and other equipment and uses it to warm water used in the bathrooms and elsewhere. Waste cooling from open freezer chests, meanwhile, helps cool the store.

DAYLIGHT HARVESTING SYSTEM

More than 200 skylights provide most of the store's lighting on bright days. On bright days, a system automatically dims or turns off the store's electric lights. On cloudy days or at night, it turns the lights up.

LED LIGHTING/MOTION SENSORS

Energy-efficient LED lighting is used throughout the store. On refrigerator and freezer cases, motion sensors turn on the lights only when a customer walks by.