Green Homes—Lighting

Incandescent lamp. Our major source of electric-powered light for more than a hundred years, it is basically a glass bulb filled with an inert gas that has a wire filament. Electric current is sent through the filament, which produces a high heat and some visible light. An incandescent’s typical life is 750 to 1,000 hours, however, it is inexpensive to buy. Under the 2008 Energy Bill, the inefficient incandescent will disappear by 2014.

Compact Fluorescent Light (CFL). This light has an electronic or magnetic ballast and a tube coated on the inside with white phosphor and filled with gas, including mercury vapor. Electricity flows through the gas, producing ultraviolet light that excites the coating, which then emits visible light. Some, but not all, CFLs are Energy Star-rated, meaning that they are supposed to meet government standards. The major benefits of an Energy Star-rated CFL include using about 75 percent less energy than a standard incandescent and lasting up to 10 times longer, meaning a savings up to $35 in energy bills over its extended lifetime. Among downsides: its mercury content and need for proper disposal, some may not work with dimmer or three-way switches, they should not be used in colder or hotter temperatures than manufacturers’ range and may burn out prematurely if turned on and off frequently. Most CFLs are being manufactured overseas, especially in China.

Solid-state lighting such as Light Emitting Diodes (LEDs). According to the Lighting Research Center’s program manager and adjunct professor Patricia Rizzo, LEDs are semiconductors—materials that fall between those able to conduct (like metals) or insulate (like wood and rubber) electricity—and they have remarkable properties. They can act as conductors or as insulators; work at room temperature, at low voltage or with direct current; and can turn on and off almost instantly. While LEDs share all these characteristics with other semiconductors, Rizzo says, the difference is that, based on the materials used to make the semiconducting “crystal,” a byproduct is light. Among LED benefits are a long life of 50,000 hours or more, low voltage, and durability. Among their downsides are high initial cost and not being available for all general lighting needs.