Subjective responses to light sources of different colour temperatures and illuminances.

User attitudes towards certain lighting conditions have as yet been predominantly a field of lighting engineering research, aiming at an optimisation of lighting conditions on the basis of averages. Therefore, data on the interindividual variability of subjective responses hardly exist. In contrast to this, the methodological approach of industrial anthropology is based on the consideration of individual variation to provide basic data which are required to design our dwelling environment. Against this background we simulated an office work situation in the light laboratory and-using semantic differentials-studied subjective responses to four different lighting conditions in which different illuminance levels were combined with different colour temperatures of the light source. Colour temperature is an aspect of artificial illumination that has rarely been considered in lighting studies. The results of our study indicate that (1) subjective judgements of the four lighting situations differ significantly, (2) relatively long, repeated exposures of test participants to lighting situations lead to a change of attitudes, and (3) subjective judgements and preferences show a considerable interindividual variation. These results suggest that lighting designs of office rooms that are merely orientated towards averages are inadequate and support lighting concepts that allow for individually adjustable light sources.