A customer browsing the aisles of a Fresh & Easy store in Phoenix spots the bottled juices in an open-air refrigerated display. He picks up a berry juice, puts it back. Grabs another selection, then checks the nutrition label.

All the while, the cooler pours chilled air into the aisle.

John Bunch, president and CEO of Phoenix-based Supermarket Energy Technologies, steps toward one of the dairy coolers and pulls down an insulated curtain that uses a magnet to stay in place.

That simple step, used when stores close, improves the cooler's efficiency by one-third. Expanded across hundreds of feet of coolers in a single store, the curtains add up to significant energy savings, Bunch said.

"The instant they put these products in their stores, they are saving money," he said.

Grocery stores keep certain items — cheese, yogurt, juice, pickles — in open displays because it is easier for customers to grab and go. Most of those cases in the United States keep wasting energy at night when the stores are closed, so a store might use as much electricity in one day for open coolers as a small home or apartment uses in a month.

Tesco, based in Britain, is using Supermarket Energy Technologies' cooler shades in all of its Fresh & Easy Neighborhood Markets in the U.S., said Roberto Munoz, neighborhood affairs manager for the company in El Segundo, Calif.

"As a company, it is smart business to make sure you reduce your energy because it saves you money," Munoz said. "But it also is good for the environment. Across the line, we are committed to these energy efficiencies."

Supermarket Energy Technologies, which Bunch launched with an $85,000 investment in 1997, is based on simple ideas. Its signature product is a device that controls the anti-fog heaters on refrigerator doors for products such as ice cream or frozen vegetables.

Those foods are kept behind glass doors that often use heaters to prevent fogging so shoppers can see the products, but the heaters work against the refrigeration systems.

Bunch's first investment in his company was securing the rights to a device called the Door Miser. The small sensors resemble something that might be used to check a person's heart rate. They monitor moisture buildup on the glass doors, kicking on heaters only when needed.

Grocers can save more than $200 a year per door, Bunch said. And, they can lease the $800 units for less than what they save on monthly bills, so they immediately see a return on the investment, he said.

Bunch offers other energyconserving products for lighting and cooler fans, which are eligible for rebates from many utilities across the country.

As an example, Bunch provided an estimate the company had prepared for a medium-sized, out-of-state grocer that included Door Misers, open-cooler curtains, fan motors and some lighting. The estimated cost was $57,000, but he said the products would provide an estimated $41,000 in annual energy-bill savings, paying off the investment in about 17 months, before rebates.