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.

The fibers would transmit sunlight to special fixtures inside the building, which also contain high-efficiency fluorescent lighting.

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.

The 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.

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