According to the U.S. Department of Energy, the electricity used to light businesses represents 25% of the energy they spend, so it's important to develop energy-saving devices. Now engineers at the Rensselaer Polytechnic Institute (RPI) have designed a simple switch which can help to reduce lighting energy consumption by 30%. This switch includes a photosensor which detects if there is enough daylight and a microcontroller that turns the lights off and on. Because of its simple circuitry, this switch is cheap to produce and can work with all kinds of light fixtures. And the researchers say that its cost can be recovered in one year by owners of new buildings. Read more...
Here is the introduction of this Rensselaer Polytechnic Institute’s Lighting Research Center (LRC) news release.
"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."
Below is a picture showing the different components of a DaySwitch™. "The DaySwitch™ consists of a microcontroller (top) that switches the luminaire on and off, and a photosensor (bottom) that measures daylight levels and sends a signal to the microcontroller." (Credit: RPI/LRC)
How does this energy-saving device work?
[It] 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).
And you can see on the pictures below that a DaySwitch™ is easy to install. "The DaySwitch™ installs in two easy steps. First, the microcontroller is installed inside the luminaire to switch the lamps on and off. Second, the photosensor is connected to the microcontroller via wires and is mounted outside the luminaire to measure daylight levels in the space." (Credit: RPI/LRC)
The research work about this switch has been published by Lighting Research and Technology under the name "The Potential of Simplified Concepts for Daylight Harvesting" (Volume 37, Number 1, January 2005, Pages 21-40). Here are two links to the abstract of this paper and to its full version (PDF format, 45 pages, 713 KB).
You also can read a flyer about the DaySwitch (PDF format, 1 page, 380 KB) from which the above pictures have been extracted.
Finally, if you're building a new home or designing the new headquarters for your company, give a call to the people at LRC: they might help you to reduce your next electricity bills.
Sources: Rensselaer Polytechnic Institute news release, April 19, 2006; and various web sites
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