Advancing the effective use of light for society and the environment.

Wednesday, April 26, 2006

Scientists Develop Simple Alternative for Harvesting Daylight and Saving Energy
By Mary Cimo
The DaySwitch™
The DaySwitch™ turns off electric lighting when it senses sufficient daylight.

Scientists at the Lighting Research Center have developed a simple, cost-effective, energy-saving device designed to harvest daylight automatically. The DaySwitch™ was designed as an alternative to traditional dimming ballast systems that adjust light levels by reducing the lamp current.

“The DaySwitch™ is designed to build end-use efficiency by reducing light energy usage in commercial buildings and maintaining occupant satisfaction,” said Peter Morante, director of energy programs at the LRC. “It is estimated that the DaySwitch™ will be able to reduce lighting energy consumption by 30 percent in buildings with significant daylight contribution through windows or skylights, allowing for a payback period of approximately three years.”

Typical dimming systems have several drawbacks, including high initial cost and difficult photosensor programming and installation. As a result, dimming systems have not permeated the market, according to Morante.

Installing the DaySwitch™
The DaySwitch™ controls a single fixture, unlike traditional sensors that control numerous lamps.

The DaySwitch™ development team, led by Morante and Richard Pysar, an electronic design engineer at the LRC, created a low-cost prototype to control individual light fixtures, unlike traditional systems where one sensor controls numerous lamps. Individual control provides flexibility for on/off control and simple installation.

The DaySwitch™ works with all conventional fluorescent ballasts—the device regulating voltage and current supplied to the lamp. Because of its simple circuitry and on/off operation, the cost to produce the device is minimal and far less expensive than traditional daylighting control systems that utilize dimming ballasts, according to the LRC research team.

“The DaySwitch™ offers a low cost option for harvesting daylight that is simple, accurate, and convenient to install,” said Andrew Bierman, senior research scientist at the LRC. “By taking advantage of natural light and using systems like the DaySwitch™, we can significantly reduce energy consumption and the growing strain on the nation’s power grid.”

The United States Department of Energy estimates that lighting accounts for one-quarter of the total energy consumed by U.S. commercial businesses.

How the DaySwitch™ works

The DaySwitch™ eliminates wasted or unwanted electric light by sensing when sufficient daylight is available to take the place of electric light, and then responds by turning off the fixture. When daylight decreases, the device turns the light back on.

A built-in microcontroller automatically calibrates the DaySwitch™, allowing for self-commissioning and easy installation and maintenance. The design also includes a light-to-frequency photodiode that, together with the microcontroller, provides accuracy over a wide range of light levels (1 to 12,000 lux).

According to the LRC research team, commercial customers can expect a two- to five-year payback in retrofit applications and a one- to three-year payback when the DaySwitch™ is built into fixtures installed in new construction.

Project partners

The LRC recently received a $198,745 award from the New York State Energy Research and Development Authority (NYSERDA) to further develop, demonstrate, and evaluate the DaySwitch™, all in an effort to commercialize the device. The LRC is partnering with Dynamic Hybrids, Inc., of Syracuse, New York, to manufacture the DaySwitch™ prototype and is currently seeking a demonstration site within New York state to install and evaluate the device.

Initial research into simple concepts for daylight harvesting was funded by the Daylight Dividends program, a national effort administered by the LRC to educate and provide evidence, guidance, and perspectives supporting the use of daylighting in commercial and educational facilities. Daylight Dividends sponsors include California Energy Commission, Connecticut Light and Power Company, Efficiency Vermont, Iowa Energy Center, NYSERDA, North Carolina Daylighting Consortium, Northwest Energy Efficiency Alliance, and the U.S. Department of Energy. The initial research results were published in Lighting Research & Technology volume 37, issue 1, which is available on the Daylight Dividends Web site.

The LRC also received a $75,000 Energy Innovations Small Grant (EISG) to develop the first DaySwitch™ prototype. EISG is a California Energy Commission Public Interest Energy Research (PIER) program designed to establish the feasibility of new, innovative energy concepts.

About the LRC

The Lighting Research Center (LRC) is part of Rensselaer Polytechnic Institute and is the leading university-based research center devoted to lighting. Founded in 1988, the Lighting Research Center has built an international reputation as a trusted and reliable source for objective information about lighting technologies, applications, and products. Its mission is to advance the effective use of light and create a positive legacy of change for society and the environment.

Rennselear Polytechnic Institute