Prominently located near the Lincoln Memorial in Washington, D.C., the United States Institute of Peace (designed by Safdie Architects) contains offices, an international conference center, education center, research facilities, and public exhibition and event spaces. The wing-like roofs connect the 300,000-square-foot building’s three curving sections, enclosing two atria below. These multi-layer translucent structures presented the most challenging lighting problem – to light the roofs with no visible sources, so they glow softly both inside and outside. Lam Partners designed the pervasive lighting theme that is present throughout: light sources are fully concealed or designed to disappear, revealing and animating, but never competing with the architecture. The result is a visual representation of peace that takes its place in the D.C. skyline.

The translucent steel-frame roofs are comprised of outer diffusing glass and an inner white membrane, with structure sandwiched in between. Extensive computer modeling, material sample testing, and a full-scale mockup in Germany were required to determine the roofs’ transmissive and diffusing characteristics, and to validate the lighting solution.

Perimeter offices are fully daylighted. Clerestories bring daylight into corridors so that they often do not need to be lighted electrically. Inexpensive T5 strips integrated continuously into the curving clerestories’ base keep the ceiling surfaces pristine and provide dual function, indirectly lighting both offices and corridors.

Supplementing the indirect lighting at the clerestories, each office has a custom T5 linear fluorescent pendant downlight with shielding designed to block views into fixtures from outside or in the atria. Lighting is controlled with manual-on occupancy sensors.

One atrium is devoted mainly to research activities, while the other contains mostly conferences and public events. In both atriums, the sense of serenity and the purity of the architecture are preserved, despite the presence of busy offices. The eye is drawn upward to the gracefully arching roof, and glowing daylit ceilings, allowing the atrium roof to remain the focal point.

In the amphitheater, the ceiling itself is the light fixture. Echoing the curving white roof of the atrium, the amphitheater is an ideal venue for conferences. Comfortable levels of illumination for both presenters and audience members were a focus. Concealed dimmable T5HO fluorescent strips in a carefully designed ceiling profile provide high levels of glare-free illumination for videoconferencing, minimizing spill on projection screens. MR16 HIR adjustable accents provide targeted lighting of the presenter and markerboard. Lighting is controlled via an audio-visual touchscreen for seamless selection of lighting scenes for various room configurations.

Integrated into the curving auditorium ceiling, dimmable T5HO forward-throw cove fixtures provide general lighting without recessed fixtures blemishing the dramatic forms. Halogen PAR38 track lighting for the stage is hidden but accessible from the floor below. Recessed PAR38 HIR adjustable accents downlight the stage and wash the stage wall. Slatted walls glow magically with hidden xenon strips lighting the cavity behind, creating a sense of openness. A preset scene dimming system controls all lighting. The result is a unique, yet peaceful, auditorium space that perfectly reflects both the architecture of the building and the Institute itself.

From below, the roof’s pure form and texture is inspiring and calming. Careful lighting design reveals the architecture and provides sufficient light levels, yet avoids the clutter of visible fixtures. T5HO forward-throw cove fixtures in the tops of walls light the atria roofs. Digital addressable ballasts allow light output to be tuned along the roof perimeter and dimmed overall, effectively accentuating the roofs’ curvature. This single source simultaneously provides the interior ambient lighting and the exterior surface glow. Above the uppermost windows, necklaces of matching MR16 HIR halogen and PAR20 CMH adjustable monopoints provide supplemental downlighting – dimmable halogen for banquets and special events, and CMH for energy-efficient punch during winter afternoons and gloomy days.

The roof’s overhang is essential to create the dramatic form of the roof, visible from both the National Mall and from the west of the city. In-grade CMH adjustable accents illuminate the overhang, seamlessly extending the glow outside to the roof’s lowest point.

A central lighting control system employs occupancy sensing, daylight sensing, scheduling, and local preset scene control techniques for maximum energy savings and occupant satisfaction.

The project achieved LEED Gold certification.

Building details and the exterior are also pristine. Stairs are illuminated solely by compact fluorescent sources hidden in plaster niches at the stair sidewalls, eliminating visible hardware in hard-to-reach overhead locations.

No conventional façade lighting is used, minimizing spill light into the sky. The glow from within the building provides most of the site illumination, allowing the remarkable building to speak for itself and allowing views into the soaring atrium. Site lighting consists solely of an LED strip in the curving bench, a soft wash on the inscription, and a few shielded bollards, without any superfluous fixtures to detract from the building’s monumental impact.