This month, we will explore the role that lighting controls play in illumination of the David C. Crago Collection at the Pettit College of Law at Ohio Northern University. Architecture by Miller/Watson Architects. Lighting design by Metro CD Engineering. Photography by Ken Colwell, Ohio Northern University. Lighting and control products included cabinetry and cove lighting (Soft Strip LED by Edge Lighting), seven-day timer controls (EI500 Digital In-Wall Timers by Intermatic), Sensor Switch nLight-based occupancy sensors, and dimming controls (Diva ELV Dimmers by Lutron Electronics).
Residing in the Taggart Law Library, the David C. Crago Rare Book and Special Collections Room houses early British and American legal treatises and other notable documents. In May 2012, the Library worked with Miller/Watson Architects to renovate the room, which had previously been closed off. The new 400-sq.ft., two-room space serves two primary functions—museum-quality display of rare books and documents in cherry and glass Amish cabinets, and a comfortable study space where faculty, students and visiting scholars can work.
Project challenges included the need for strict climate control and selection of light sources that would support visual needs while satisfying best practices for storage and use of rare books. An environmental control system was specified to maintain constant temperature and humidity. For the lighting, Miller/Watson collaborated with Metro CD Engineering to select light sources that would protect the light-sensitive materials in the collection from the degrading effects of ultraviolet and infrared radiation.
“The elegant and classic design of the space required lighting that would not itself be a focal point, but rather highlight the displays while providing enough light to comfortably work in the space,” says Justin Schultz, PE, RCDD, LEED-AP ID+C, lead electrical engineer for Metro CD Engineering and an Ohio Northern University alumnus.
Concealed LED strip lighting was integrated into the ceiling cove to distribute soft, indirect illumination in the space. Manual low-voltage electronic dimmers can be used to lower light levels from full output to eight percent. LED tabletop luminaires provide supplementary task lighting for study.
“LED lighting can typically be dimmed, but the lighting designer must pay extra attention to the details for ensuring compatibility between the lighting fixture and the controls,” notes Schultz. “Most commercial lighting cut sheets list the compatible dimmer models that have been tested with the lighting fixture. Oftentimes, the minimum dimmed level is determined by the model of dimmer used.”
LED lighting is also integrated into the cabinetry, illuminating the rare books and artifacts on display. This type of application is well suited to the LED source, which is directional and minimizes ultraviolet and infrared emission.
“The LED strip lighting sources not only met the rare books’ preservation requirements, but also allowed such a low profile that the light sources are all hidden from view,” says Schultz. Long service life was another deciding factor in choosing LED.
The use of seven-day digital timer switches ensures the lighting is turned OFF when the room is on display but not in use.
At full output, the lighting power density level came in at a low 0.74W/sq.ft.—far less than energy code requirements—with significant additional energy savings resulting from the ongoing use of dimmer controls. The project earned the Illuminating Engineering Society’s Edwin F. Guth Memorial Award for Interior Lighting Design as well as its Lighting Controls Innovation Award.
“I have a passion for lighting because it blends the artistic side of engineering with some of the latest advances in technology,” says Schultz. “Although we are not yet at the point that LED lighting should be universally specified, LED is the future of lighting design.”