Minimum semicylindrical illuminance and modelling in residential area lighting

Abstract

The recognition of persons is extremely important in considering the safety aspects of residential area lighting. Semi-cylindrical illuminance is the appropriate descriptive parameter, as shown by experiments carried out under real outdoor conditions. The minimum level is used as a basic design criterion. On the other hand, values above 25 lux do not enhance recognition. Other experiments were set up to examine any correlation of modelling effects of the human face with the ratio of vertical to semi-cylindrical illuminance. It is shown that this ratio presents only a geometrical function relative to the object person position. Luminaire concepts are discussed in connection with guidelines for semi-cylindrical illuminance and glare.