It's been shown to improve employee productivity and create a better office environment, to increase sales in stores, and to help students score higher on achievement tests. And while its doing all this, it also provides a way for companies, schools and other facilities to save money on energy bills. "It" is none other than the sun. Programs from EPRI (Electric Power Research Institute), Palo Alto, Calif., help maximize the use of available sunlight for indoor illumination, helping building owners "harvest" daylight so they can rely more on lighting control strategies that save up to 80% of lighting energy under optimum conditions by letting the sunshine in.

Lighting normally accounts for about 41% of the energy used in commercial buildings, including air conditioning to cool lighting loads. Companies that use daylight-harvesting strategies to their fullest potential start by replacing power-hungry magnetic fluorescent ballasts with energy-saving electronic ones, then combining sensing switches that turn off the lights when people are out of an office space. The next step involves mounting photocells on the ceiling to sense the level of light coming through the windows and to signal the ballasts to gently dim the indoor illumination to take advantage of available daylight.

Daylighting controls with dimmable ballasts in building retrofits have typical paybacks of two to eight years, according to John Kesselring, senior project manager in EPRI's commercial technologies and services business area. Plus, he says hardware costs for dimming ballasts and advanced controls are coming down. Companies interested in daylighting control strategies can obtain a number of resources through EPRI, including practical design guidebooks for both building retrofits and new construction, and lighting-related software products. For more information contact EPRI at 650-855-2733, e-mail chop@epri.com, or visit the institute's Web site at www.epri.com.