Light emitting diodes, or LEDs, are small light sources illuminated by the movement of electrons through a semiconductor material.
LEDs produce more light per watt than incandescent bulbs, making them exceptionally energy efficient. In fact, many LEDs use up to 90 percent less energy than an incandescent bulb to produce the same amount of light.
LEDs are a directional light source that point light a specific way, unlike incandescent bulbs which emit light in all directions. Much of the light produced by incandescent bulbs can be lost within the light fixture or reabsorbed by the lamp. For many fixture types, including recessed downlights, fluorescent lighting units, and under-cabinet fixtures, it is common for 40-50 percent of the total light output of the lamp to be lost before it even exits the fixture.
Because LEDs are directional lighting, the lamps are especially useful for task lighting, such as under cabinets, in hallways and in recessed and downlight fixtures. They also perform well when subjected to frequent on-off cycling.
Most people still expect LEDs to cast a cool, bluish light, but technology is improving. When introduced to the market, LEDs produced a cold light because of high correlated color temperatures (CCTs), often above 5000 Kelvin (K). These days, warm white LEDs with CCTs ranging from 2600K to 3500K, have significantly improved.
LEDs are currently more expensive, per lumen, than more conventional lighting technologies. This is attributed mostly to production needs and process. However, because LEDs are designed to have a long life, reporting approximately 35,000 to 50,000 hours of useful life, LEDs far surpass incandescent or halogen sources in terms of cost over the course of its life.
LEDs indicate end-of-life by dimming over time.
Issues to Resolve
LED manufacturers continue to work with lighting experts to fine tune the following: