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  LED Technology You will find here useful informations and publications regarding state of the art LED technology and LED's light efficiency.


The LED Efficiency

Lamps and Luminaires using state of the art LEDs are able to achieve class A of the energy efficiency classification - referred to the EU commision directive 98/11/EG for household lamps (see further informations below).


LED Light Generation Theory

LEDs generate light not by heating a material as light bulbs do by heating the filament (to some thousand degree Celsius). The LED consist of a semiconductor chip (diode) in which a forward voltage shifts electrons (-) and holes (+) to a different energy level (left side, bottom figure). During recombination (unification) of electrons and holes photons (i.e. light) are generated from the released energy. The forward voltage of the LED (which is nearly Eg, the so called bandgap voltage) is only dependent on the material system of the chip. High bandgap voltages produce high energetic light (short wavelength, e.g. blue) while low bandgap voltages generate low energetic light (long wavelength, e.g. red). The wavelength (colour) of the LED is nearly independent of LED current and temperature.


light source * LS W** LD
light bulb 50 10 5
halogen bulb 1100 25 30
xenon bulb 3200 90 90
LED,2007,2.5W 220 90 40
LED,2009,2.5W 300 140 60
LED,2011,Lab. -- 240 -
LED, theor. Max. -- 420 --

*) Supplier data
LED 2011: labratory values

**) The efficacy (light per electrical power, Lm/W) depends also on LED current. Hence an average value is used for this comparision.

LS = light emission [lm] per LED
W = efficacy [lm/W]
LD = light density [cd/mm2]

Light Efficacy

An ideal LED would convert 100% of the applied electrical energy to light. Real LEDs convert only a small part of that energy to light. However, a bigger part is converted than in light bulbs which convert a large part to heat. Upcomming research and development will improve the light efficiency of LEDs increasingly. An improvement of 35% per year for the comming time frame is expected.

The left side table presents a comparision of some light sources regarding light efficiency. As one can see, the LED has overhauled already some of the commonly used light sources regarding light efficiency, as (normal) light bulbs and also halogen light bulbs.


light source ALT*
light bulb 1.000 h
halogen bulb 3.000 h
low energy light bulb 8.000 h
LED 60.000 h

*) ALT: Average life time based on manufacturer information.

Reliability & Life Time

LEDs are based on semiconductor material. They are operated, in contrast to light bulbs, at moderate temperatures - mostly below 100°C junction temperature (i. e. the temperature of the semiconductor chip). For this reason they reach a much higher life time and better reliablility than light bulbs.

LEDs reach life times of over 60.000 hours (based on information given by LED manufacturer). This means - operated at 8h a day and 200 days per year - a life time of approximately 30 years. Therefore, our lamps operate completely maintenance free during the life time with no change of the light source.
Conventional light bulbs reach 1000 hours only (see also table on left side for comparision).


light source EEC *
light bulb E-F
halogen bulb C-D
low energy light bulb A-B **
LED (2011) A

*) Energy Efficiency Classification, acc. EU directive 98/11/EG

**) note that those lamps may need several minutes to reach that efficiency after switched on


The EU directive 98/11/EG of the commision dated January 27th, 1998 desribes the labling of lamps (figure on top of the page). Although LED-lamps are not explicitly mentioned there LED-lamps using state of the art LEDs (year 2011) are able to reach class A.

For example typical values are shown in the table (left side): energy saving light bulbs reach class A - B, Halogen bulbs C - D, normal light bulbs E - F. We do not lable our lamps and spots in this way as officially this is not specified today for LEDs. However we use this as an indication to promote the energy saving level of LEDs.