PEOPLE: concept design, Skidmore, Owings and Merrill LLP, Washington, D.C.; design/build, Skanska USA Building Inc., Parsippany, N.J., and HKS Architects Inc., Washington; landscape architect, Mahan Rykiel Associates, Baltimore; consultant, ValleyCrest Landscape Development, Calabasas, Calif.; and waterproof membrane and green-roof-system installer, Prospect Waterproofing, Sterling, Va.

GREEN POINTS: Designed and built to provide a world-class workplace for 6,000 employees, the Census Bureau’s design features sweeping curves and glass cladding with vertical wooden louvers. Two interconnected wings rise from a 1-story monolithic base and curve over a garden courtyard. Green roofs encompass about 88,000 square feet (8175 m2) of space. Extensive and intensive green-roof systems were used with planting media ranging from 3 1/2 inches (89 mm) to 3 feet (0.9 m). About 10,000 square feet (929 m2) of extensive green roofing is located over the lobby; 35,000 square feet (3252 m2) atop the fourth floor of the north building; and 30,000 square feet (2787 m2) atop the fifth floor roof of the south building. The deeper, intensive systems are located on portions of the land bridge that extends through the center of the building and across the courtyard. Red and subtle green plants populate the roofs to emphasize the different kinds of vegetation throughout the area. The roof assembly consists of a roofing membrane applied directly to the deck, protection course and root barrier, insulation, water retention and drainage elements, filter fabric, growing media and vegetation.

PROJECT PROVIDED BY AMERICAN HYDROTECH INC. / CHICAGO / WWW.HYDROTECHUSA.COM