Light colour
We experience our surroundings not just as brightness and darkness, light and shadow, but also in colour. The light radiated by lamps has an intrinsic colour. It is known as light colour and is determined by colour temperature in Kelvin (K). The higher the temperature, the whiter the light.
The light colours of lamps are divided into three groups:
- warm white (ww) light is found homely and comfortable
- neutral white (nw) light creates a more businesslike atmosphere
- daylight white (dw) light is suitable for interiors only where illuminance is 1,000 lux or more.
The light colour of lamps | |
Light colour | Colour temperature in Kelvin |
warm white | < 3,300 |
neutral white | 3,300 - 5,300 |
daylight white | > 5,300 |
Lamps that emit light of the same light colour may have different colour rendering properties. This is because of the different spectral composition of the light they emit. It is thus not possible to draw conclusions about colour rendering quality from light colour. Light colour and colour rendering properties can be altered by special attachments, which direct, filter or colour the light.
Determining colour temperature
Colour temperature is used to denote the colour of a light source by comparison with the colour of a "black-body radiator". A "black-body radiator" is an "idealised" solid body – e.g. made of platinum – with a reflective radiance of zero. It thus absorbs all light that falls on it. When it is slowly heated, it passes through a range of colours – from dark red, red, orange, yellow and white to light blue. The higher the temperature, the closer the colour to white.
