Exhibitions:

15.-21. Januar 2018

Köln

Halle 4.2 Gang C Nr. 024

16.-19. Februar 2018

München

Halle A2, Stand 200/303

18.-23. März 2018

Frankfurt

Halle 4.2 Stand C20

What are the basic terms used in relation to lighting?
Those who work with light, sell or explain lighting systems, must know the following basic terms in order to be able to describe light and its effects.

1. Luminous flux (lumen = lm)
This is the total light output of a light source (lamp).The luminous flux is of particular importance, because it is the quantity that is used to describe the "brightness" of a light source. For example, a 100 watt filament lamp would produce about 1,360 lumen. A 30 watt fluorescent lamp would produce about 1,600 lumen. The luminous flux is therefore the light output by the lamp.

2. Luminous intensity I (candela = cd)
Luminous intensity is the light flux of a lamp or light bulb emitted in a specific direction. The type of reflector of a lamp or luminaire determines the light intensity distribution and is frequently shown as a light intensity distribution curve.

3. Illumination E  (lux = lx = lm/m²)
Illumination is divided by the light flux of a lamp into lumen, where one lux is an illumination of one lumen per square metre. The light of a full moon would provide an illumination of about 1 lux, good workplace lighting about 1,000 lux, and on a sunny day outdoors, the illumination intensity would be about 100,000 lux.

4. Luminance L (cd/m²)
Luminance is a measure of the brightness of an illuminated surface. In addition to the luminous intensity, the reflection factor of the surface is also decisive.

5. Luminous efficiency?
The luminous efficiency (Lumen per watt) is a measure of the efficiency of lamps. The more light (lumen) obtained for the amount of power (watt) input, the less the costs (Euro) are and the better the economy. Whilst tungsten-halogen lamps provide about lumen per watt, this can about 75 lumen per watt with fluorescent lamps.

6. Luminous colour and colour temperature
The luminous colour of a light source is described by the colour temperature. With filament lamps this is about 2,700 Kelvin (K) and with fluorescent lamps this is above 6,000 K. A light source with 3,000 K has a larger proportion of red, a light source with 6,000 K has a larger proportion of blue.

7. Colour rendering
Colours are perceived as natural in daylight. Artificial light can offer good colour rendition if it allows objects or their colours to appear as if in natural daylight. There are generally four colour rendering grades, whereby distinction is made between values from 1a (best value) to 4 (worst value).