Scientists Develop Simple Alternative for Harvesting Daylight and Saving Energy
Troy, N.Y. — Scientists at Rensselaer Polytechnic
Institute’s Lighting Research Center (LRC) 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™ consists of a photosensor
(bottom) that measures daylight levels and sends a signal
to the microcontroller (top) that switches the luminaire on
Photo by Rensselaer/LRC
“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.
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
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
“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.
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 www.lrc.rpi.edu.
Contact: Mary Cimo
Phone: (518) 687-7174