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LED Glossary


Solid-state lighting (SSL) - A technology using semi-conducting materials to convert electricity into light. SSL is an umbrella term encompassing both light-emitting diodes (LEDs) and organic light-emitting diodes (OLEDs).


Light-emitting diodes (LEDs) - LEDs are based on inorganic (non-carbon-based) materials. An LED is a semi-conducting device that produces light when an electrical current flows through it.


Organic light-emitting diodes (OLEDs) - OLEDs are based on organic (carbon-based) materials. In contrast to LEDs, which contain small point sources, OLEDs are made in sheets that provide a diffuse area light source. OLED technology is developing rapidly, but is still some years away from becoming a practical general illumination source.


Luminaire efficacy - A measure of the efficacy of the complete luminaire, or fixture, taking into account the optics, thermal design, and other design factors that impact efficacy. It is calculated by measuring the total light output of a luminaire, divided by the amount of power drawn by that luminaire. It is expressed in lumens per watt (lm/W).


Source efficacy - A measure of the efficacy of the light source, separate from the fixture. It is calculated by measuring the total light output of a lamp/power supply system, divided by the power drawn by that system. (It does not account for losses caused when that system is installed in a fixture.) It is expressed in lumens per watt (lm/W).


Illumination - The distribution of light on a horizontal surface. The purpose of all lighting is to produce illumination.


Lumen - A measure of light emitted by a lamp. As a universal reference point, a 100-watt incandescent lamp emits about 1750 lumens.


Color rendition (CRI) - How colors appear when illuminated by a light source. Color rendition is generally considered to be a more important lighting quality than color temperature. Most objects are not a single color, but a combination of many colors. Light sources that are deficient in certain colors may change the apparent color of an object. The Color Rendition Index (CRI) is a 1–100 scale that measures a light source’s ability to render colors the same way sunlight does. The top value of the CRI scale (100) is based on illumination by a 100-watt incandescent light bulb. A light source with a CRI of 80 or higher is considered acceptable for most indoor residential applications.


Color temperature  (CCT) - The color of the light source. By convention, yellow-red colors (like the flames of a fire) are considered warm, and blue-green colors (like light from an overcast sky) are considered cool. Color temperature is measured in Kelvin (K) temperature. Higher Kelvin temperatures (3600–5500 K) are what we consider cool and lower color temperatures (2700–3000 K) are considered warm. Cool light is preferred for visual tasks because it produces higher contrast than warm light. Warm light is preferred for living spaces because it is more flattering to skin tones and clothing. A color temperature of 2700–3600 K is generally recommended for most indoor general and task lighting applications.



Energy / Labor

LED lighting offers you many benefits including dramatic energy and labor savings. Receive an estimate of these savings with our Energy/Labor Savings Calculator.

Why LED ...

The U.S. Department of Energy (DOE) reports that*

(LED) products made for the commercial sector last at least 25 times longer than incandescent lighting, and at least 3.5 times longer than typical fluorescent lighting, including CFL bulbs. (See GSSI suggested LED Replacements for CFL bulbs here.)

(LED lighting's) durability ensures consistent performance and rare breakage.

LEDs produce far less heat than incandescents. This reduces air conditioning needs.

* 2008 Partner Resource Guide 

These are but a few of the reasons the time is right for you to consider solid state LED lighting. To learn more contact us or call (800) 366-8884 today.

by GSSI Group, Inc.

7510 Williamsburg Drive
Cumming, GA 30041, USA
(800) 366.8884
(770) 844.8080 (fax)

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