The Fourth Source: Light-Emitting Diodes (LEDs) for General Illumination
Learning Objectives - After this course, you should be able to:
- Discuss how LEDs work, and describe their relative merits for general illumination applications.
- List general criteria for evaluating LED light sources and fixtures.
- Evaluate LED fixtures based on specification criteria for downlight, outdoor and other general-illumination applications.
The light-emitting diode, or LED, is changing before our very eyes. The computer-age lighting source technology was, until recently, considered mainly for decorative and specialty applications. A common refrain was that "LEDs are meant to be seen, not seen by." Yet recent and significant leaps in illumination and operational performance have turned the lighting world upside-down. Over the last few years, lighting designers and architects have begun using LED lighting-also known as solid-state lighting (SSL)-fixtures for general illumination applications, in workplaces, schools, retail buildings and facilities.
LED and fixture manufacturers agree that the newest generation of products is ready for the "prime time" of general illumination. But even companies that have been actively involved in LEDs for many years have only recently released fixtures intended for general illumination: downlights, wall washers, flood lights, and the like. Manufacturers were waiting for the capability to produce fixtures that would be highly performance oriented, providing whiteness, brightness, good energy efficiency, and the power needed for indoor and outdoor use.
There's no question that LEDs are highly energy efficient. LED-illuminated exit signs consuming less than 5 watts (5W) per sign have been used for years now. And every traffic signal awarded the U.S. Environmental Protection Agency's Energy Star label has been designed to use LEDs.