A Proposed Luminance Basis for a Lighting Code

Lighting codes in terms of levels of illumination incident on the visual task have served a valuable purpose for over fifty years. When based on sound principles, they are still valid for the lighting on the work. The lighting of the building interior, however, should not have to be constrained by the lighting on any specific visual task, and should be planned in relation to the design of the whole building. Experiment and observation show that the degree of satisfaction given by lighting is regulated by the brightness pattern in the visual field. Good lighting requires selective illumination on the work, together with an environment free from excessive brightness and glare. The relation between the work lighting and the building lighting should properly be developed in terms of apparent brightness, and an outline is given of the research programme necessary for this purpose. Meanwhile an interim stage is proposed for a lighting code to be based on existing knowledge of visual comfort in relation to brightness distribution in the visual field.