Green Lights for Greenbelt
Spectacular lighting, with the environment and occupant in mind, makes a cultural center a more enjoyable place
Siva K. Haran, P.E., Senior Electrical Engineer, WMA Consulting Engineers, Ltd., Chicago
Designed to complement its natural setting and provide flexible, functional space, the Greenbelt Cultural Center is a 7,300-square-foot multipurpose facility for the Lake County Forest Preserve District in Waukegan, Ill. As architects and engineers at Teng & Associates, Chicago, developed the project, a critical aspect was the selection and design of lighting systems to both illuminate and accent the new building.
Interior creativity-and technology
Inside the facility, a combination of creativity and technology enhances the flexibility of the space while adding ambience and accents. Lighting in the entry reception area, for example, is inviting; cove lighting and general lighting provide directional cues, while low-voltage, 2-inch multifaceted-reflector (MR-16) suspended track lights along the wall provide visual cues to accentuate the exhibits. The exhibits are in their own "pool of light," designed to integrate visually with the square windows to give the "museum-wall" desired by the client.
General downlights in the corridors are 32-watt, triple-tube compact-fluorescent fixtures (3,500K) that provide glare-free lighting with a smooth beam. Low-iridescence nonimaging reflectors ensure a 45-degree cutoff to the lamp and lamp image; the one-piece design eliminates light leaks in the ceiling.
The multipurpose hall is spacious with high ceilings, and a spectacular wall of windows faces the natural outdoors. The hall is designed to be used for meetings, conferences, classes, weddings, receptions and exhibits, so its lighting system has to be flexible enough to fit these applications and remain energy efficient. Fluorescent dimming provides this flexibility, independent channel control and efficiency.
The layout of pendant lighting fixtures follows the structural and architectural integrity of the space. The 4-foot fixtures are direct/indirect type with varying perforations on top to provide even illumination in the sloped wood ceiling, and each is fitted with three T8 "octron" lamps and one three-lamp electronic dimmable ballast. The dimmable ballast enhances room functionality. Full-range ballasts were selected for this application as most appropriate where dimmed fluorescent lamps replace incandescents and provide flexibility and energy efficiency.
Other significant attributes of the lighting-system design include:
All fluorescent lamps in the building are a proprietary low-mercury type.
Track lights provided for the exhibits and stage area are also on a dimming system.
Exit lights are energy-saving models that feature long-life light-emitting diode (LED) lamps.
The south view of the building incorporates a wall of windows with exterior metal-halide "can" lights and interior pendant fluorescents selected to complement and integrate with the architecture. These glass walls offer panoramic vistas of the adjacent forest preserve, so glare from the fixtures was considered.
When designing the illumination for an outdoor application, the first step should be to determine the goals for the application. Is the objective drama, functionality or a combination of the two? In lighting the cultural center, the objectives were to enhance the building's appearance and to heighten the experience of every patron who walks through.
Recessed, ground-mounted fixtures along the exterior walls, for example, are 100-watt metal halides, which bring out the color and texture of the building's Mankato limestone walls. These ceramic-discharge tubes combine the white light and high efficacy of metal-halide lamps with a color stability of within +/-200K. Excellent color rendition-85, where 100 equals the color rendering of incandescent lamps-produces a natural color representation of the stone walls.
The fixtures are mounted 1.5 feet from wall so that the light grazes the wall to bring out the texture of the stone, creating a light and shadow display on the wall. The west wall of the building acts as a backdrop for an outdoor theater stage; on the east wall, stark silhouettes of plantings stand against dramatic backdrops of light.
The construction of an outdoor amphitheater on the west side of the facility is planned to be completed soon. The designed lighting solution for the tent structure is truly key in amplifying the architectural imagery and expressive nature of the design, which is intended to suggest a bird in a natural setting. Uplights diffused against the fabric of the tent structure are planned that should create a luminous glow and visual statement. Uplighting the translucent tent is expected to create background illumination and help the public perceive the entire space by drawing attention to the structure. Also, the warmth of the indirect lighting is hoped to serve as an inviting beacon.
The tent lighting and all exterior lighting-including parking fixtures-are metal-halide sources with a 4,100K color temperature, offering a color that contrasts with the 3,000K sources used on the building.
The lighting design is an integral part of the effective facility architecture and engineering. In the words of Chris Ayers, manager of the Greenbelt Cultural Center, "The lighting is spectacular here. You can tell that lot of thought went into the selection of the lighting for both the inside and the outside."
Ayers finds the exterior fixtures especially satisfying: "The ground lighting outside is the perfect accent to the Mankato stone," she says. "These lights are inset into the ground, which makes them disappear until they are needed."
The interior lighting design is also appreciated. "The inside lighting in the gallery is state of the art," says Ayers. "All of our artists have remarked as to how the lighting helps to bring out the colors in their paintings. The small design makes them almost disappear and keeps the focus where it should be-on the artwork."
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