The first LED was developed by Nick Holonyak Jr., at General Electric Company in Syracuse, New York in 1962. His first practical visible-spectrum (red) LED was extremely expensive on the order of $200 per unit, and had only limited applications. In the 1970s, Fairchild Optoelectronics was able to commercially produce LED devices at under five cents each. These early products were used in indicator lights in expensive equipment. Over time as prices decreased further, and the technology improved LEDs were used in other appliances such as TVs, radios and calculators. But it wasn't until the last decade that LEDs started to be used in general lighting applications. As they continue to improve in efficiency and price, we are seeing more and more general lighting applications being taken over by SSL.  

              There are a few well known manufacturers of LEDs (CREE, Philips Lumileds, Osram Sylvania, GE, Nichia) producing high output devices designed for general illumination. You can expect similar high levels of quality from these makers, including documentation supporting their performance claims. Additionally there are many LED manufacturers that produce low output devices you often see in seasonal decorative lighting as well as lower quality LED lightbulbs.  

              An LED luminaire is a complete lighting fixture using LEDs as its lightsource. The marketplace is full of manufacturers that take LEDs and incorporate them into commercially applicable luminaires. While LEDs don't produce the same amount of heat an incandescent light bulb does (about 90% of power consumed by an incandescent is emitted as heat), they do generate heat that must be conducted and then radiated away. This requires proper heat sinking and ventilation to ensure the LED Luminaire lives up to its promised life performance claims.  

With the rapid advancements and increasing supply of LED luminaires in the marketplace there are several tools in place to help consumers find quality LED luminaires.

The US Department of Energy together with the Illuminating Engineering Society North America (IESNA) have issued several test procedures by which to compare luminaires.

LM-79 is the IESNA-approved test method for measuring LED Luminaires accurately and repeatable under normal operating conditions. The resulting test reports total flux (Lumens), electrical power (Watt), efficacy (lm/W) and chromaticity (CRI/ CCT). These absolute photometry procedures test the luminaire as a whole and produce reliable results that allow users to compare SSL fixtures based on the same criteria. While LM-79 does not guarantee quality, it does ensure the user that the stated performance is accurate.      

LM-80 is the IESNA-approved test method for measuring the lumen maintenance of LED light sources. LM-80 specifies procedures for determining lumen maintenance of LEDs and LED modules (but not luminaires) related to effective useful life of the product. LED Luminaires that use LEDs with LM-80 test reports increase the likelihood of a quality fixture. However, it is still up to the luminaire manufacturer to properly use the LED with adequate heat sinking and suitable power supplies.

TM-21 provides a method for determining an LED luminaire or integral replacement lamp's expected operating life, based on initial performance data collected per IES-LM-80. This test procedure has just received final approval from the IES board last week. It will give SSL Fixture manufacturers a test method for determining the projected lifetime of a luminaire as a whole under normal operating conditions.

According to the Department of Energy website: "Solid-state lighting (SSL) technology has the potential to cut U.S. lighting energy usage by one-quarter and contribute significantly to our nation's climate change solutions."