Some projects take a few years to complete and others take decades; the latter was the case with the Oklahoma State Capitol Dome. The building was nearing completion just as the United States was entering World War I. Materials slated for the capitol were diverted to the war effort, and given the then-current state of events and projected dome costs of $250,000, an alternate roof design was selected. But 80-plus years of civic perseverance has prevailed.
The state hired architecture and engineering firm Frankfurt-Short-Bruza Associates to determine if the existing structure could support a high dome. The original 1914 construction documents-which were still around-indicated that the building had been completed with footings to support a dome, and further testing confirmed it was structurally feasible; it was just a matter of securing funds. A fundraising team was able to find private donations for the $21 million project that was officially dedicated in November 2002.
Coordination between architect and lighting designer occurred from the start. 'The goal was to make the building feel like it was alive at night, to be a beacon that reads from a distance, and to be just as elegant during the day,' explains lighting designer Keith Yancey of LAM Partners. The dome is broad brushed with light, and then certain features are highlighted to give the dome depth. The lighting system is controlled by photocells and programmable relays located in the dome's double-shell, and controls are preset for full daylight, full nighttime, full nighttime wash, and a nighttime after-hours mode.
Envisioning how the lighting scheme would interact with the dome's surfaces on both the interior and exterior was a unique challenge, since there was no existing structure to mock-up. 'We did a few calculations on Lightscape,' explains Yancey,' but basically we had to draw on past experience to create a system that had redundancy and flexibility.' The architectural details were developed to disguise the luminaires and lighting hardware in special niches and coves, keeping them hidden from people standing in the rotunda or outside the building.
The light is focused on the building through strategically placed luminaires. On the exterior, ceramic metal halide sources were chosen to provide the best color rendering for the architectural precast stone and concrete. Narrow-beam fixtures focus on the architectural details while limiting stray light.
The dome oculus has a stained-glass center backlit with fluorescent sources. At the apex, a coffered ceiling is cross-lit with PAR38 ceramic metal halide fixtures, and PAR38 metal halide fixtures with spread lenses wash a ring of 16 vertical windows and backlight the peristyle columns. PAR20 metal halides highlight the pilaster capitals. T5HO fluorescent coves illuminate the railing on the lowest level and create a scrim to shield views of the lighting hardware behind.
'The completion of the dome was a once-in-a-lifetime project for all the team members involved,' says architect Fred Schmidt. Changing the city skyline, the Oklahoma Sate Capitol now has a top worthy of its base, and a lighting scheme that lets the architecture be seen. A|L
Project Oklahoma State Capitol Dome, Oklahoma City, Oklahoma
Lighting design LAM Partners, Cambridge, Massachusetts
Architecture Frankfurt-Short-Bruza Associates, Oklahoma City, OK
Project size 5,000 square feet
Watts per square foot 18,000 watts maximum, interior and exterior
Installation costs $21 million for the entire project
Photographer Greg Hursley
Manufacturers Altman, Color Kinetics, Engineered Lighting Products, Hydrel, Kim, Lithonia, Osram Sylvania, Philips, Quality Lighting, Rab Electric
please visit archlighting.com for full specification information.