Facts about LEDs

Light source of the future
LEDs are the light source of the future, and more and more people are using them for lighting – both indoors and outdoors.

Even today, LEDs are 5 times as energy efficient as conventional incandescent bulbs, and colour rendering is on a par with fluorescent tubes.

The use of LEDs for lighting has been limited up to now, mostly because LEDs have not been sufficiently energy efficient and colour rendering has not been good enough. However, there have been significant improvements in recent years.

High energy efficiency
Commercially available LEDs are 5 times as efficient as incandescent bulbs, 3 times as efficient as halogen bulbs, and equal to energy saving bulbs – with an efficiency of typically 50-60 lm/W.

Energy efficiency of a light source is calculated by looking at the quantity of light emitted by the light source (the lumen package), and the energy consumption of the light source (in Watts). Energy efficiency is stated in lumen per watt (lm/W). When calculating the energy efficiency of a light source, you should remember that the energy consumption of a light source includes the power loss in the transformer, electronic ballast unit or driver.

Switch on instantly
LEDs switch on instantly and provide their full strength immediately. In the long term, the small components in LEDs are suitable for dimming the lights, and the light doesn’t change colour when dimmed, which is what happens with incandescent and halogen lights. Nevertheless, LED bulbs sold on the market today are not capable of being dimmed, because they do not yet contain the necessary electronics.

Colour properties
The colour properties of a light source are relevant to white light, and are described as colour temperature (expressed in Kelvins, abbreviated as K) and the colour rendering index (CRI) or Ra index. The CRI ranges between 0 and 100 and indicates how good a light source is at reproducing a number of reference colours. A CRI of 100 is the best.

The light from LED sources is either warm (typically 2,700-3,000 K), neutral (3,500-4,500 K) or cold (4,500-10,000 K). A comprehensive selection of LEDs is available with a CRI of over 80. The best LEDs have a CRI of over 90.

Long lasting
As a rule, LEDs have a lifetime of between 25,000 and 50,000 hours. The lifetime depends to a large extent on how they are used. High temperatures and high current loads can quickly take their toll on an LED, which in many ways resembles an ordinary electronic component.

Unidirectional light
LEDs project all their light forwards, whereas the most common light sources emit light in all directions. This is why LED bulbs are best suited to lamps that project light in one direction, such as spot lights and lamps that solely light downwards.

More about LEDs
If you would like to read more about the technical background for designing with LED bulbs or fittings with LEDs, then have a look at our ‘Design with LEDs’ page, which you will find in the Public and Commerce section of our website.