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You are here: > News > April 25, 2006

DaySwitch™ Adjusts Lighting Per Daylight Availability

The DaySwitch™, developed by Rensselaer Polytechnic Institute, consists of a photosensor that measures daylight levels and sends a signal to the switch to turn off the electric light as the sunlight gets bright enough -- an ultra-simple solution to wasted electricity.

The DaySwitch™ consists of a photosensor (bottom) that measures daylight levels and sends a signal to the microcontroller (top) that switches the luminaire on and off.

Photo by Rensselaer/LRC

TROY, NY, USA -- Scientists at Rensselaer Polytechnic Institute’s Lighting Research Center (LRC) have developed a simple, cost-effective, energy-saving device designed to take advantage of daylight automatically.

The largest application for this technology would be in office complexes in which lighting control is done automatically.

Traditional dimmer switches such as those that reduce halogen light emission by reducing voltage are not applicable to fluorescent lights, which often predominate in large office complexes. A very high voltage is required to create the ions which collide with the mercury vapor to create the light.  One cannot simply rheostat down the voltage level.

This is explained by Dr. Barna Szabodos, computer science professor and Director of the Power Research Laboratory, at McMaster University, Hamilton, Ontario, Canada, who developed an unrelated fluorescent dimmer system a few years ago. (; Jan. 19, 2006)

“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.” This is an on-the-cheap setup usable only where this exterior light is available.

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.

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 are published in Lighting Research & Technology volume 37, issue 1. 

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 Lighting Research Center
The Lighting Research Center (LRC) is part of Rensselaer Polytechnic Institute of Troy, N.Y., and is the leading university-based research center devoted to lighting. The LRC offers the world’s premier graduate education in lighting, including one- and two-year master’s programs and a Ph.D. program. Since 1988 the LRC has built an international reputation as a reliable source for objective information about lighting technologies, applications, and products. The LRC also provides training programs for government agencies, utilities, contractors, lighting designers, and other lighting professionals. For more information, visit

About Rensselaer
Rensselaer Polytechnic Institute, founded in 1824, is the oldest technological university in the United States. The university offers bachelor’s, master’s, and doctoral degrees in engineering, the sciences, information technology, architecture, management, and the humanities and social sciences. Institute programs serve undergraduates, graduate students, and working professionals around the world. Rensselaer faculty are known for pre-eminence in research conducted in a wide range of fields, with particular emphasis in biotechnology, nanotechnology, information technology, and the media arts and technology. The Institute is well known for its success in the transfer of technology from the laboratory to the marketplace so that new discoveries and inventions benefit human life, protect the environment, and strengthen economic development.

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Mary Cimo
Phone: (518) 687-7166
E-mail: <cimom {at}< >

See also

Page posted by Sterling D. Allan Apr. 25, 2006
Last updated December 24, 2014





"It is harder to crack a prejudice than an atom." // "I'd rather be an optimist and a fool than a pessimist and right." -- Albert Einstein

ADVISORY: With any technology, you take a high risk to invest significant time or money unless (1) independent testing has thoroughly corroborated the technology, (2) the group involved has intellectual rights to the technology, and (3) the group has the ability to make a success of the endeavor.
All truth passes through three stages:
   First, it is ridiculed;
   Second, it is violently opposed; and
   Third, it is accepted as self-evident.

-- Arthur Schopenhauer (1788-1860)

    "When you're one step ahead
of the crowd you're a genius.
When you're two steps ahead,
you're a crackpot."

-- Rabbi Shlomo Riskin, (Feb. 1998)


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