Abstract
This thesis describes a programme of study of the distribution of light flux within interiors and, in particular, some aspects of prediction and measurement. After a brief survey of the development of methods of lighting calculation, work is described which resulted in the recommended method of selecting a suitable maximum value of spacing to mounting height ratio which was published by the Illuminating Engineering Society in 1971. Further work is described showing additional factors that must be taken into account when applying the method. This is followed by a discussion of the methods of illuminance calculation in current use. The work, by others, which has a bearing on the present position with regard to the distribution of light flux in the enclosed space is reviewed and it is shown that the geometric mean of the cylindrical and horizontal illuminance may be a better indication of total illuminance than is scalar illuminance. The construction of a model room is described and a series of experiments using this room are detailed. This study confirms that the Bean and Esterson table, specifying the number of points of measurement required to estimate average illuminance, published in the 1968 I. E. S. Code is reliable, and that the use of finite difference equations for predicting utilance values is satisfactory. The study demonstrates some of the difficulties associated with the use of sharp cut-off bat-wing distributions, and that a satisfactory MPR value does not ensure satisfactory uniformity at the walls. In the final section work is described in which measurements of illuminance were made and photographs taken to illustrate the lighting condition at a point. It is shown that the currently proposed illuminance ratios successfully predict most of the changes observed. Where appropriate recommendations are made, together with suggestions for further studies.