Skip to main content

SWIFT EVOLUTION OF THE LED

No evolution of any lamp was as dynamic as the one of the light emitting diode (LED). Since the first commercial available LED in 1962 the efficiency multiplied every decade.

This rapid evolution leads to the problem of documenting the state of the art. Professionals don’t expect the increase of efficiency to break off within the near future. This will lead to a clear LED dominance within the lighting technology. LEDs with more than 160lumen/watt have already been developed but are not yet available on the market. Practically every year new LED innovations are presented which enhance the efficiency even further.

As an expert for special solutions we always provide our customers with up-to-date and very efficient lighting, this is possible because of the high flexibility of our production, which allows for a fast and easy integration of technical innovations.

Comparison of light yield

The light yield describes the relation between incorporated electrical energy and the light flux radiating from the light source. This value is getting represented in lumen/watt. This high efficiency results from the LED’s functionality. Within the LED the light emerges by emitting photons with a effectiveness of almost 100%. Unfortunately this is not the only factor determining a light’s effectiveness. A loss of power is affiliated to the emerge of the light from the depletion layer within the semiconductor. Absorption, as well as reflection, are physical effects you need to consider. These reduce the efficiency to about 30%. Compared to a regular light bulb (5%), this value is still very high.

A further advantage over other lamps becomes apparent when looking for a specific light colour. For example, for incandescent lamps the desired colour is achieved by a colour filter, which absorbs the major part of the broad colour spectrum and transmits only one colour. On the other hand an LED generates monochromatic light directly. This allows producing the colour you want to achieve without further loss in efficiency. Due to the high efficiency of LEDs the energy consumption is reduced. This results in less operating costs and a smaller CO2 footprint. With LED solutions you illuminate not only economically you also protect nature. The light yield is always given with respect to the overall system. Therefore the efficiency refers to the luminaire and is declared in luminaire lumens/watt.

Lifetime and their determination by LM-80 & TM-21

The luminous efficiency of an LED continuously decreases with constant conditions over time. This behavior, which is also referred to as degradation, results from the migration and expansion of impurities in the crystal lattice of the diode. An immediate failure of the LED, similar to the failure of a light bulb, does not occur as long as the LED is driven correctly. The following graphic shows the life of various lamps compared, taking into account the luminous flux decline over time.

The service life of LEDs is usually indicated by the manufacturers in the form of “L70 (9k) >50,000”. This expression refers to the lowering of the LED light output to 70% after a minimum of 50,000 hours, based on a 9,000 hour test series. Two standards have internationally prevailed to obtain this lifetime. First, the LM-80 test method, on the other hand, the calculation method TM-21. The LM-80 process is a pure life test in which the light output is recorded versus the time for three different housing temperatures. The minimum duration of the test is 6,000 hours. TM-21 on the other hand is not a test but a method of extrapolation that is a projection. For this, the LM-80 determined values ​​are used and a prospective light decline is calculated. The method is limited to the six-fold test time of the LM-80 test. So when 50,000 hours or more are provided by the TM-21-process the lamps must have been tested for over 8,000h. Most times the lifetime is indicated by the L70 value, which describes the amount of time until only 70% of the luminous flux remains. Sometimes the manufacturer states the calculated light yield at 50,000 operating hours.

Rapid amortization of LED solution

While LEDs are more expensive to buy than conventional lighting, a payback calculation shows how quickly the investment pays off. Not only the sharp drop in electricity cost is important, you also have to take the falling change and maintenance costs attributable to the long lifetime into consideration. That’s why the switch to LED solutions frequently pays out even for projects completed in the past. A required lights change is assisted by the standardized design which will facilitate installation. We are also happy to calculate the payback period for your specific project and show you how quickly the use of LEDs pay for itself. We can calculate your savings using the indication of your current price, the maintenance and the respective operating hours.