LED Lighting: A Green Option for Homeowners
Above: Swiecaca lampa typu LED, © Piotr Frydecki / Wikimedia Commons / CC BY-SA 3.0
Household LED Lamps
By Stephanie M. Chambers
LED lighting has become the green choice for homeowners. Prices are dropping and LED technology is improving rapidly. LED lamps have a longer lifespan, and are much more efficient than incandescent and fluorescent lighting. If you take into account the electricity savings and the numerous bulbs that you won’t have to change, you’ll see that LED lamps are the best option. Some manufacturers are experimenting with LEDs that can produce as much 300 lumens per watt, while an incandescent bulb produces only 14-17 lumens per watt. As of 2016, most LED lamps use about 10% of the energy required by incandescent lamps. Many LED lamps offer a 30,000 (or more) hour life, compared to the normal 1,000 hour life of a standard incandescent bulb, or the typical 8,000 hour life of a CFL lamp. Unlike CFL and fluorescent lighting, LEDs require no warm-up time and come to full brightness as soon as they are switched on, just like an incandescent bulb. In addition, LED lamp life is not reduced by switching on and off, as it is with CFL and fluorescent lamps. An LED by itself does not emit light in all directions, but when properly grouped in a lamp they can radiate light in a 360 degree angle, just like the incandescent lights we know and love.
How Light-Emitting Diodes Work (In Layman’s Terms)
The LED light bulbs we use in our homes today, are basically a series, or array, of light-emitting diodes assembled into a lamp. When configured for use in existing fixtures, standard shapes and connections are used, such as the familiar “Edison screw” base found on most incandescent lightbulbs. The same way many devices in our homes use DC voltage, like computers, LED bulbs convert incoming AC power to the required DC power, through a switched-mode power supply.
LEDs sound complex, but they’re no more complicated than an incandescent light. An LED is just a semiconductor light source. Specifically, a p-n junction diode, where p-type (positive) silicon touches n-type (negative) silicon. The p-type silicon contains extra electron holes, and the n-type silicon has extra electrons. An electron hole is the lack of an electron inside an atom or atom lattice (crystal structure) where an electron could exist, but does not. When voltage is applied, electrons recombine with electron holes inside the LED to release photons, or light particles, through the process of electroluminescence.
Because white light is needed for general purpose lighting, and LEDs do not emit white light without modification, various colors of light (RGB) must be mixed from multiple LEDs, or a phosphor coating can be applied to convert the light frequency from its original color to white. Most commonly, yellow phosphor is placed over a blue LED.