Abstract
Some of the visual objectives for which different levels of illumination are, or may be, recommended are considered and mention is made of the kind of experimental data available for the development of illumination prescription systems. Such experimental data underlie the recent Russian and American recommendations which are discussed briefly. It is taken as always desirable that lighting installations in regularly occupied interiors should provide sufficient illumination to create an agreeable environmental or ambient luminance, irrespective of the specific visual tasks occupants may be required to do: hence, what illumination may be recommended reasonably for securing this basic amenity luminance in places of work is considered. The existing British analytic method of finding basic values of illumination for various definite visual tasks is examined and a modification is proposed to simplify practical use of the method. In view of this, a new definition of the visual performance criterion is proposed and a general, although moderate, increase in recommended levels of illumination is likely to be consistent with this.
Get full access to this article
View all access options for this article.