Hart Senate Office Building: Energy Generation and Natural Light Conservation

The Hart Senate Office Building, completed in 1982, is the third office structure designed and built to serve the United States Senate.  At the direction of the Architect of the Capitol (AOC), KCCT designed a notable energy generation and natural light conservation upgrade for the building.  The energy component is centered upon the installation of approximately 30,000 square feet of photovoltaic (PV) panels, or 45% of the total roof area, and produces about 148 kW VDC of electricity, which back feed the building’s air-handlers.  Concurrently, the thermal envelope was enhanced by a new IRMA roofing system with ballast composed of heat reflective colored pavers and gravel.

Conservation of the quality of natural light provide by the original skylights was a priority for the AOC as it sought to upgrade all 180 skylights in the building and to increase energy efficiency.  The new energy-efficient skylights maintain this quality of illumination which is vital to the interior facing spaces and essential to fully appreciate Alexander Calder’s colossal Mountains and Clouds mobile/stabile sculpture housed in the central atrium.

The Hart is the first PV retrofit project completed by the AOC and one of the largest of any federal building in the Washington area. The combined energy generation/conservation measures represent approximately 274,000 kWh of electricity which is equivalent to the annual energy use of 25 average U.S. households, or 42,000 square feet of energy-efficient office space.




Washington, DC


100,000 SF


Architect of the Capitol




• Architecture
• Historic Preservation
• Construction Administration