Although three of the façades have glazed portions, a minimum of daylight reaches the interior of the store. An opaque alcove behind the glazing filters the natural light, and a large vestibule limits daylight from reaching the merchandise arrayed beyond the entry. Because of the supermarket’s proximity to a residential neighborhood, local building regulations prohibited skylights. Instead, along with other mechanical equipment, the roof supports a 400kW combined heat and power fuel cell, that provides 90 percent of the store’s energy.
Following the layout prepared by Supervalu’s Design Services Group, the principal lighting systems define departmental boundaries, provide visual interest, and aid in wayfinding around the sales floor. The principal luminaire installed throughout the store is a 2×2 recessed volumetric fixture with an internal driver created to deliver the overhead ambient light. The fixture consists of two identical 26W boards that are fitted with an industrial specular reflector. Heat dissipation is minimal, based on each fixture’s heat sink at the LED junction. Direct-heat reduction is achieved as the LEDs are attached to a sheet-metal backing with an aluminum strip. Two mounting techniques are employed to deliver the light to the product displays below: For example, over produce, the fixtures are suspended from the dark-painted ceiling by aircraft cables connected to a T-bar frame 14 feet above the floor. In other areas, products on shelves are lit by luminaires that are flush-mounted into a dropped ceiling. Supplemental 23W wide-spot LEDs provide accent lighting and wall washing.
Bill Ballweg, a Lithonia product development manager who participated in the fixture’s design, says that its dimming capability is key to its energy reduction success. Since opening last fall, the store’s system, which has been dimmed by one-third, is now successfully running at 66 percent power. Wiring for a system of 11 dimming zones in groups of 15 to 20 overhead fixtures has proven effective. Kitchen of Osram Sylvania coordinated with Lithonia to supply the appropriate dimming power supply for the basic 2×2 overhead fixture. “Color temperature throughout the store is 3500K with a CRI of 82 so that there is a full light spectrum for the best color rendition of all displayed products,” Ballweg says. Lumen output is 3,300, and with the help of a reflector, a footcandle level of 70 to 90 is achieved throughout the entire space.
One exception to this overhead lighting strategy is in the double-height entry vestibule. Instead of the 2×2 luminaires, there are LED circular downlights and concealed lighting around an octagon-shaped cove. The 6-inch-diameter down-lights have a white reflective dome and 38W LEDs in an indirect array.
Complementing the overhead ambient lighting is an accent of light around the store’s perimeter at the ceiling line. This continues at the signage headers for different specialty areas, such as the Bakery, Cheese Shop, and Sushi and Seafood departments. LED striplights are used to illuminate the titles.
The more sculptural lighting elements in the store are the cloudlike wave panels of translucent canvas that are lit from above. These panels provide a free-form contrast to the symmetrical rows of gondolas (merchandise displays) with stacked shelves in the grocery sections below. Suspended 11 feet above the floor, each individual panel is illuminated by linear, dimmable LED arrays composed of linked 8-foot and 4-foot sections that provide a total of 16W per linear foot. Overall, the store achieves 1.5W per square foot.
For Tarver, the Chestnut Hill project was one of the most complicated he’s ever worked on. “It was like going to the moon,” he says. “An all-LED store had never been done before. We had to create all the products and the systems to make it happen.” Even with adding the power to operate the separate sets of escalators needed for both customers and shopping carts, the store is on target with meeting its energy-saving goals. “There were some calculated risks … some gambles … in promising to deliver an all-LED facility in the time allowed. But we trusted really good vendors with histories of past successes, and they came through for us,” Tarver says.
Since opening, the store has hosted tours of the facility for other food-chain operators, sharing information about the technologies used and the experience of developing an all-LED facility. An achievement in bringing LED lighting technology to a complete project, Star Market’s Chestnut Hill store is literally “lighting” the way, as solid-state lighting becomes more the norm than the exception in retail settings.
Details
Project Star Market, Chestnut Hill, Mass.
Client Supervalu, Eden Prairie, Minn.
Architect of Record Yarosh Associates, Mashpee, Mass.
Interior Designer Supervalu Store Design Services, Eden Prairie, Minn.
Lighting Designer Technology, Energy, and Environmental Dept., Supervalu, Boise, Idaho
General Contractor Suffolk Construction Co., Boston
Structural Engineer Chapin Associates, Norwood, Mass.
Mechanical Engineer Richard P. Gramlich, P.E., Largo, Fla.
Electrical Engineer DC Engineering, Meridian, Idaho
Fire Protection Protection Consultants Inc., Centerville, Utah
Energy Consultants Aztec Energy Partners, Conyers, Ga., and CTA, Billings, Mont.
Photographer Mark Steele Photography, Columbus, Ohio
Project Size 53,000 square feet
Manufacturers Amerlux; BetaLED; Lithonia Lighting; Melissa Lighting; Osram Sylvania; Philips; SPI Lighting