Capitol Crossing is a 2.2 million square foot mixed use development occupying the air rights to the 6.8 acres above Interstate 395 in Washington, D.C. It is the largest air rights project that has ever been undertaken in Washington. Planned as the first “eco-district” in the nation’s capital, it includes five buildings built over three blocks, with office, retail, and residential space. The project aims to fulfill Pierre-Charles L’ Enfant’s original vision of the city by reconnecting the otherwise empty space to the street grid and urban fabric.
The North block is comprised of two buildings supporting three towers, which provide multiple amenities for the primarily commercial tenants, residents, and visitors to the space. Enveloped in glass curtain wall, the towers are connected on the second level by the Pedestrian Way, a 55 feet wide gallery which offers a lively retail environment. Suspended glass screen walls spanning 50 feet create prominent entrances to the west and east lobbies along Pedestrian Way and to the main entry on 3rd street into the concourse, and lobbies on the ground and second floor. A green roof with terraces on both towers offers panoramic views to the Capitol and Washington Monument. The west building has an additional green roof with a terrace on the fifth floor. The project also includes a below grade parking garage for 1,146 cars and 440 bicycles is below the three blocks.
The exterior of the complex is composed of two curtain wall types. Between the third and twelfth floors, the curtain wall has a grid of floor to ceiling 2″ wide polished stainless steel frames on a 5′ module set beyond a plane of satin finish stainless steel. At towers’ corners and recesses, the curtain wall is flush structural glazing. The subtle contrast of curtainwall types gracefully accentuates the building’s geometry. At every floor level, fritted glass fades into clear glass at the height of 3′-6″. Along the exterior of levels one and two, a granite cornice and series of pilasters form the base of the buildings.
The project incorporates numerous assets to enhance the buildings’ sustainability. The 45,108 sq. ft. of green roof mitigates heat island effect and addresses storm water runoff. Advanced energy recovery devices, indoor air quality controls, water conserving plumbing fixtures, and the elimination of supplemental irrigation help minimize consumption of energy and resources. The insulated glass on the exterior improves thermal efficiency. The Pedestrian Way features two eco-chimneys, which will address the below-grade vehicle exhaust. The project anticipates LEED Platinum certification.
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