However, at night, the building and dome lost much of its lustre with a lighting scheme that created uneven lighting. The rotunda was primarily lit with 400W high-pressure sodium lamps from an extremely steep angle, resulting in deep shadows above the curve of the dome and at the upper cupola. A mix of lower wattage metal halide lamps and high-pressure sodium lamps combined to create hot spots and uneven colours on the stone and gold leaf.
"The overall result was somewhat muddy and inconsistent," says Ted Ferreira, principal at CD+M Lighting Design Group in Atlanta. CD+M was hired to work with the principal architecture firm, Lord, Aeck & Sargent Architecture, to create a new lighting scheme in conjunction with a $70million building rehabilitation. CD+M then collaborated with GE Consumer & Industrial's Lighting business to supply the lamps for the project.
The new lighting scheme had a number of goals, including emphasising the newly restored limestone and brilliant gold leaf materials on the dome with a palette of complementary colours, while also highlighting architectural details.
A combination of approximately a dozen each of GE's 1,000W Multi-Vapor metal halide lamps and 1,000W Lucalox high-pressure sodium lamps in narrow beam floodlights balance the colour of limestone and gold surfaces. The Multi-Vapor metal halide lamps provide energy efficiency and long life. The Lucalox high-pressure sodium lamps offer longer life, similar to that of fluorescent lamps (24,000+ hours) with maximum efficiency. "The GE Lucalox lamps are energy efficient and provide a compact point source like incandescent, allowing good optical control," says Mary Beth Gotti, manager of GE's Lighting & Electrical Institute in Cleveland.
More than 40 narrow beam uplights manufactured by Hydrel Lighting were furnished with GE low-wattage ConstantColor CMH ceramic metal halide lamps to accentuate the column and moldings. "GE's CMH lamps have very minimal colour variation lamp-to-lamp and imperceptible colour shift, while providing improved lumen maintenance never before seen with standard quartz metal halide lamps," says Gotti.
To help overcome some of the mounting challenges, CD+M turned to Phoenix Lighting, manufacturer of the building floodlighting system. Phoenix created computer models of the building to determine the best locations for long-throw spotlighting of the rotunda and to confirm illuminance levels 360° around the dome.
The new exterior lighting design has received great feedback with its dramatic transformation of the nighttime look of the Georgia State Capitol building. "The finish, colour and architectural elements can now be viewed at night for the first time in the history of the building," says Susan Turner, AIA, a principal at Lord, Aeck & Sargent and leader of the architecture firm's Historic Preservation Studio. "The lighting is much more even now, adding both subtle and dramatic touches that showcase this architectural gem."
(Jim Evans)
