Rapid progress in solid-state lighting (SSL) research and development (see DOE's SSL R&D Portfolio ) has resulted in the advent of light-emitting diodes (LED) for general lighting applications. This section of the website provides information on the important performance characteristics of white light LEDs for general illumination, with particular emphasis on energy efficiency and lighting quality. Energy efficiency of light sources can be characterized in several different ways. Luminous efficacy indicates how much light the source provides per watt of electricity consumed. This is stated in lumens per watt (lm/W). Another measure of energy efficiency is the total watts a device consumes in providing the intended service. Both measures are important to consider.

Source: Cree, Inc.

Lighting quality is a subjective term, but generally includes color quality (including appearance, color rendering, and color consistency); illuminance levels (the amount of light the light source provides on a task or surface); photometric distribution of the light source in a fixture or luminaire; lifetime; ease of maintenance; and cost.

This section is designed to provide useful information for energy efficiency program sponsors, utilities, government agencies, lighting fixture manufacturers, lighting designers, and others who are interested in energy-efficient lighting technology.

• LED Basics: This section provides basic information on how LEDs work, and explores important technical issues (energy efficiency, color quality, lifetime, thermal management) in greater detail. 

• LED Applications: Learn more about using LEDs for recessed downlighting, undercabinet, and portable desk/task lighting applications. Information on additional applications will be added to the site over time.

• LED Measurement: This section provides information about measurement protocols and test procedures that are currently being developed or revised to accommodate specific attributes of LEDs.

以上信息来来之http://www.netl.doe.gov/ssl/usingLeds/index.htm