When designing the lighting for a room, care should be taken to avoid mixing light sources with different correlated colour temperatures.
| Light source | Colour temperature T |
|---|---|
| Daylight | 6,500K |
| Flourescent (daylight) | 6,000K |
| Flourescent (white) | 3,500K |
| Flourescent (warm white) | 3,000K |
| Tungsten halogen | 3,000K |
| Incandescent | 2,800K |
Light sources and their correlated colour temperatures
Mixing will work as long as the luminaires are either in close proximitiy or far away. If they are not, coloured shadows and areas will be the results.
Colour of a blackbody, depending on its temperature
Mixed light is accepted for task lighting. However, when two adjacent rooms are lit with light sources that are very dissimilar, problems with the colour adaptation could arise. Such schemes are therefore best avoided. This is also important when maintaining and replacing lamps. If an office is lit with cool white fluorescent, lamps should not be replaced with warm white ones unless all of them are replaced at once. The difference in colour temperature will stick out and could be the cause of discomfort. Even if is doesn't, the result would not be aesthetically pleasing.
If a lighting sceme is designed to be a supplement to daylight, lamps with a high colour temperature should be used, such as cool white fluorescent.