The first light emitting diode (LED) was developed in 1962 and was red in colour. White and blue LEDs were not developed until 1994. LEDs typically run at a very low current, but Phillips developed the first high power Led in 1999 capable of running at 1w.
The efficiency of LED bulbs has advanced dramatically in the last 2 – 3 years. Despite the traditional method of measuring the brightness of bulbs by the input wattage (a 100w bulb is brighter than a 60w bulb), this is no longer a relevant measure. Electrical input is measured in terms of watts and light output is measured in lumens.
A traditional incandescent bulb produces 15 lumens/watt while a traditional fluorescent bulb produces 60 lumens/watt. In 2003 LEDs developed by CREE were able to produce 65 lumens/watt. By 2009 105 lumens/watt was possible, with 140 watts/lumen achieved in 2011 by Nichia and 254 watts/lumen were achieved in 2012 by CREE.
These laboratory results have been translated into commercial products where the light output is about 80 -120 lumens per watt in 2014. This means you can replace a traditional 100w light bulb with a LED bulb that uses just 12 watts. A traditional halogen bulb puts out about 650 lumens of light and can be replaced with a 6 watt LED bulb.
With LED bulbs you can now save both money and the environment.
