The Role of Models and Artificial Skies in Daylighting Design

Much has been done in recent years to improve the standard of daylighting design and to establish daylighting technology on a sound basis. The paper discusses the special part which experiments in model rooms under artificial skies have played in this work; the techniques of model construction are discussed in some detail and reference is made both to models for photometric examination of lighting quantity and for subjective appraisal of lighting quality. It is concluded that, although the natural sky must be used for some subjective appraisals in models, the instability of the luminance pattern of the natural sky, often accompanied by inclement weather, renders it unsuitable for detailed photometric analysis. The luminance and luminance pattern of an artificial sky can be chosen to suit the particular experiment, and the conditions remain stable over long periods enabling the effects of changes in the model to be examined in detail. The basic principles of the design of artificial skies are discussed. Some instruments used in daylighting studies are described.