Task and background lighting

Abstract

A series of experiments are described in which groups of twenty observers were asked to complete questionnaires relating to the task and background lighting of an experimental room. The background lighting was varied over a wide range for task illuminances of 200 and 400 lux. The results obtained were used to answer the questions, "What is the lowest value of general illuminance that should be provided in any continuously used interior?" and "What should be the relationship between the task area illuminance and the background illuminance to ensure that visual conditions are satisfactory?"