February 1, 2006 — Thanks to advances in physics, light-emitting diodes (LEDs) will soon move from traffic lights and electronics panels to home lighting, bringing dramatic energy savings, adjustable colors for ambiance, and light-shining furnishings.
TROY, N.Y. -- Do you know what your home will look like in the future? The future is now here with new lights that almost never have to be changed.
The special lights use the same technology used in newer traffic lights and on computers. They're easy to install and can save you a lot of cash.
Changing the lighting in your home may be as easy as switching out a tile. Light-emitting diodes, or LEDs, are making light installation a do-it-yourself project. The demo room at Rensselaer Polytechnical Institute's Lighting Research Center in Troy, N.Y., is a view into the home of the future.
Nadarajah Narendran, director of research at the Lighting Research Center at the Rensselaer Polytechnic Institute, says, "The lighting can be rearranged just like furniture in a room."
LEDs can be housed in flexible tiles because they're durable, smaller, long lasting, and not hot to the touch. "In an incandescent lamp, it's the heating that causes the filament to light up. Whereas in an LED it's the charges -- the positive and negative charges -- when they come together, they combine and give light," Narendran says.
The intensity of the light can change, along with the color, unlike traditional lights that after installed are always the same.
"So if you want to create mood lighting you have that option with LEDs because you can change the color with a touch of a button," Narendran tells Ivanhoe.
LEDs, however, aren't just about ambiance. Narendran says, "We are talking about 50- to100-times longer lifetime from incandescent lamps." LED lights only need to be changed every 15 years, saving consumers 90 percent in energy costs and making the choice of LEDs a worthwhile switch.
Narendran says he expects LEDs to be commercially available in the next three years to four years.
BACKGROUND: Researchers at Rensselaer Polytechnic Institute are developing a 20 by 15 foot demo room to display a light-emitting diode (LED) lighting tile that can be snapped into place like sheetrock to form ceilings and walls. Though this tile is still in a prototype, LED technology is already used in exit signs and traffic signals, as well as digital clocks plasma TV screens, and remote controls. The hope is that the demo room will demonstrate the advantages of LED lighting for other applications.
HOW IT WORKS: LEDs are essentially tiny light bulbs that fit into an electrical circuit, but they are lit solely by the movement of electrons in a semiconducting material. A diode is the simplest semiconductor device. It is made by bonding a section of a positively-charged material to a section of a negatively-charged material with electrodes on each end so that it only conducts electricity (in the form of free-moving electrons) in one direction whenever a voltage is applied to the diode. Electrons move in a series of fixed orbits around the nuclei of atoms. Whenever an electron absorbs extra energy from the added voltage, it jumps to a higher orbital, and when it returns to a lower orbital, it emits the extra energy as a photon -- a particle of light. LEDs are specially constructed to emit a large number of photons, unlike ordinary diodes, in which the semiconductor material absorbs most of the light energy before it can be released. LEDs are also housed in a plastic bulb to concentrate the light in a particular direction.
BENEFITS: LED lighting consumes 50 percent less energy than traditional sources. It is four times more energy efficient than regular light bulbs because more of the energy is converted into light than is lost as heat. There is no glass or filament, as in a light bulb, so LED tiles would last forever, and the tiles are so rugged, someone can jump on them without breaking them. LED lighting also covers the entire color spectrum of visible light so lighting can change from one color, or tone, to another with just one touch of a control panel.
Note: This story and accompanying video were originally produced for the American Institute of Physics series Discoveries and Breakthroughs in Science by Ivanhoe Broadcast News and are protected by copyright law. All rights reserved.
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