Sustainability and energy conservation are built into the DNA of Market of Choice, a regional natural and organic grocery store operator based in Eugene, Ore. The family-owned chain employs energy-saving air curtains, sells power generated from its own 130.0 kW solar photovoltaic rooftop system and composts its own food wastes. And it is in the middle of an energy-saving lighting retrofit. Here are the details on the major elements of the company’s energy-saving efforts:
AIR CURTAINS: To date, air curtains have been installed in seven of Market of Choice’s eight locations. Most stores use a stainless steel Zephyr or MaxAir air curtain (from Berner International, New Castle, Pa.) that matches the modern look of the automatic door entrances on the interior. The curtains, which are installed on the front end and shipping doors, were originally used to keep customers and employees at the checkout protected from drafts. But they also have resulted in significant energy savings for the stores.
The curtains are activated by a limit switch triggered when the door opens and deactivated on a five-second delay setting via Berner’s digital, programmable Intelliswitch controller.
Here’s how it works: Air curtain technology draws interior air from the facility and discharges it through field-adjustable (+/-20 degree) linear nozzles that “seal” the doorway with a non-turbulent air stream that meets the floor approximately at the threshold of the door opening. A properly sized and AMCA-certified (Air Movement and Control Association) air curtain can contain approximately 70% to 80% of that air and return it to the space. Because the air curtain discharges air at velocities generally in the range from 1,000 to 3,000 ft/min., it effectively prevents outside air from entering the space (and also flying insects).
The curtains are critical to Market of Choice stores because their front entrances are cost-effectively designed with automatic sliding doors versus vestibules. The payback for air curtains ranges from one to two years and depends heavily on periodic checks for proper airflow performance. Store managers at Market of Choice are trained by the installing electrical contractor, Revolution Electric, Eugene, Ore., to clean reusable filters and adjust the air curtain’s 10-speed fan to suit patrons and weather conditions.
LIGHTING: The grocery store operator is moving from traditional fluorescent lamps to LED lighting in its reach-in coolers/freezers. The LEDs use approximately 18 to 20 watts of energy as compared with a traditional fluorescent that consumes 44 watts, emit less heat for the refrigeration system to dissipate, are brighter and have a five times longer life cycle than the fluorescents. After a test installation, the chain is installing them in other locations.
“They’re saving energy, they’re brighter and they perform well,” said Market of Choice sustainability coordinator Scott Cook. “We believe we can cut our freezer-light energy use by 60% with this program.”
In addition, the extensive produce sections in the stores will be outfitted with LED drop-in bulbs in HID 42-watt fixtures. For the change-out, Revolution Electric is experimenting with 18-watt wide beam spread LEDs (from Osram Sylvania, Danvers, Mass.) and also with 14-watt LEDs (from Cree, Durham, N.C.), which have an 87 color rendering index (CRI).
SOLAR: Market of Choice deploys 562 rooftop-mounted, 175-watt photovoltaic solar modules (from SolarWorld, Hillsboro, Ore.) to generate electricity. A PV power inverter connects the 130.0 kW DC system to the electric grid. The retailer sells the power to Oregon’s largest customer-owned utility, Eugene Water & Electric Board (EWEB), which pays .12/kWh on the 10-year contract. The chain’s corporate offices use solar lighting generated from solar tracking skylights. A monitor/control system adds lumens of artificial light when solar lighting isn’t sufficient near dusk, dawn or on overcast days.