Low energy consumption
LED stands for Light Emitting Diode. This is an electronic device very similar to a computer chip.
Modern high power white LED chips used for LED lighting are actually blue underneath (though research is looking into using green and purple). The light emitted by the chip is then absorbed by a phosphor coating. This coating then glows and re-emitts the light across the visible spectrum of light.
For this reason early white LED lighting tended to have a very strong blue component giving a harsh colour rendering. Over the last 10 years and the last 2 in particular the phosphors have been improved to provide very comfortable soft lighting with a slightly wider colour spectrum to halogen giving blues and greens a slight extra lift.
“LED lighting does not produce heat!” This common misconception is unfortunately wrong. LEDs do produce heat although none of that heat is in the beam. Like any other device that consumes energy it produces heat – this means that a 5W LED will produce 1/10 of the heat that comes from a 50W halogen. Unfortunately where a halogen lamp has to be hot to work (with the bulb reaching temperatures of 300 degree C or more) LEDs deteriorate when they get hot.
The generally accepted consensus seems to be that a good quality LED if kept below 60 degrees C will loose no more than 30% of it’s output over 50,000 hrs. This time until 70% lumen output is known as L70. Most incandescent and fluorescent sources will loose at least 30% of their output before they die. This is therefore used as the ‘useful’ life of an LED light.