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Introduction to LED Lighting


Light Emitting Diodes (LEDs) are part of a class of lighting called Solid State Lighting (SSL). Unlike incandescent or compact fluorescent lamps (CFLs), LEDs are small electronic components that convert electricity into light. An electrical current passes through semiconductor material, which illuminates the tiny light sources we call LEDs. The heat produced is absorbed into a heat sink. Common LED colors include amber, red, green, and blue. There is actually no such thing as a “white” LED. To get white light, the kind we use for lighting our homes and offices, different color LEDs are mixed or covered with a phosphor material that converts the color of the light. The phosphor is the yellow material you can see on some LED products. Colored LEDs are widely used as signal lights and indicator lights, like the power button on a computer.

LEDs are now being incorporated into bulbs and fixtures for general lighting applications. LEDs are small and provide unique design opportunities. Some LED bulb solutions may look like familiar light bulbs and some may not, but can better match the performance of traditional light bulbs. Some LED light fixtures may have LEDs built–in as a permanent light source.

The best white light LED lamps can meet or exceed the efficiency of compact fluorescent lamps—but many LEDs currently on the market do not. LEDs are sensitive to temperature and electrical conditions, and LED fixtures must be designed carefully to take this into account; many manufacturers are not yet experienced in such design. According to ENERGY STAR, “Thermal management is probably the single most important factor in the successful performance of an LED product over its lifetime because the higher the temperature at which the LEDs are operated, the more quickly the light will degrade, and the shorter the useful life will be”. A poorly designed LED product can flicker, shift in color, look dim, offer uneven light, or continue to use power when it is turned off after less than a year of use.

However, research and development in this area is very active, and more efficient LED devices are appearing on the market every day. Luminaires are manufactured with the LEDs already installed as an integral part of the device, a practical approach because thermal management is addressed and incorporated into the luminaire design, ensuring the long life that can be attained with LED diodes. ENERGY STAR states that  “all LED products that have earned the ENERGY STAR have been tested to ensure that they properly manage the heat so that the light output is properly maintained through the end of its rated life”. For more information about ENERGY STAR requirements about LED bulbs, please click this link: