The Tenley-Friendship Library, part of the DC Public Library system, was designed inside-out by way of a collaborative process. The Freelon Group and Horton Lees Brogdon Lighting Design worked together to develop architectural, electric lighting, and daylighting systems with an eye toward creating a healthy building that consumes 31 percent less energy than is standard for a 21,472-square-foot structure. The project focuses on connecting visitors to the community with exterior views that bring the diurnal cycles of light inside the library. The design team conducted extensive sun angle studies to develop a system of external vertical fins that protect the otherwise transparent insulated glass enclosure, allowing controlled daylight to filter into the interior while cutting down on heat gain. The central circulation spine also makes ample use of natural light with a glass roof that directs sunlight onto an interior feature wall of the same copper color as the external fins. The daylighting scheme is supplemented with T5 fluorescent fixtures set on photo-activated dimmers. The T5s are set in coves to maintain a constant level of light, day or night. In the stacks, the T5s are integrated with the flange of the exposed-steel structural members, where they uplight the ceiling. The stacks themselves feature T5s in cantilevered fixtures that provide focused downlighting to the bottom shelf.

During most days, the daylighting is sufficient to keep 70 percent of the electric lights dimmed all the way down, a factor that contributed to the project's LEED Gold certification.

Jury Comments: A complete examination of how light and architecture can work in unison. • Love the way the vertical fins are turned into an architectural feature, while still serving as a principal lighting device. • Excellent use of daylighting.


Project: The Tenley-Friendship Library, Washington, D.C.
Design Architect/Architect of Record: The Freelon Group, Research Triangle Park, N.C.
Associate Architect: R. McGhee & Associates, Washington, D.C.
Lighting Designer: Horton Lees Brogden Lighting Design, Culver City, Calif., and New York.
Photographer: Mark Herboth Photography
Project Size: 21,472 square feet
Project Cost: $10.2 million
Lighting Cost: $500,000
Watts per Square Foot: 1.023
Manufacturers: a•light, Bega, Hydrel (Acuity Brands), Lutron, Philips Lightolier, Prudential, Selux, Spring City