Sunlight in a tube
Posted March 10, 2005
Courtesy Oak Ridge National Laboratory
and World Science staff
Scientists are developing a technology
to save energy by transmitting sunlight into buildings through tubes.
Indoor electric lighting is
the largest consumer of electricity in commercial buildings, according to
researchers at the Oak Ridge National Laboratory in Oak Ridge, Tennessee.
Their new system. called
hybrid solar lighting, would reduce this energy usage with
fixtures that supplement or completely replace electric light with sunlight, at
times when it’s
available. The system is called hybrid solar lighting.
In the system, a
rooftop collector concentrates and sends sunlight through optical fibers,
tubes made of special, high-purity material that transmit light by reflecting it
down their inner walls.
In the hybrid solar lighting
system, the fibers would transmit sunlight
would to special fixtures inside the building, which also contain high-efficiency fluorescent
When the transmitted sunlight completely illuminates each room, the electric lights stay
off. The researchers discussed on their work in the current issue of the
laboratory’s magazine ORNL Review.
When less natural light is available during cloudy days and at night, a sensor activates controls that increase electric lighting adequately to supplement natural lighting and maintain desired illumination
levels, according to the magazine.
The laboratory’s Jeff Muhs spearheaded the development of the technology,
organizing a collaboration of more than 25 organizations in 13 states to help in the
research, the magazine said.
In 2003, the group hosted
the first Annual Hybrid Solar Lighting Summit, which was attended by both public
and private stakeholders, including architects, utility executives, lighting
designers, green power and clean energy advocates, and prospective
Oak Ridge labortory plans to help install hybrid solar lighting at the
headquarters of the Sacramento Municipal Utility District in Sacramento, Calif.,
under a contract by the California Energy Commission, according to the magazine.
The laboratory also plans to install an HSL system in a Wal-Mart store in Kauai, Hawaii, to evaluate energy savings and sales trends associated with HSL daylighting.