Objective assessment of glare at outdoor workplaces

Abstract

Lighting system in a modern building environment involves many different aspects of workplaces, primarily visual comfort and health. The glare may reduce visual comfort and may be one of the indirect causes of accidents at work. Glare assessment at outdoor workplaces is a difficult task. In this instance, the Glare Rating (GR) is used as a numeric measure of glare sensation. International standards set out the rules for determining the GR as well as the required limit values of GR that provide acceptable glare sensation for specific workplaces. In practice, GR is not measured and simulation software is used to determine the GR value. However, such an assessment of the glare is not always reliable. We present the GR measurement method for outdoor workplaces using imaging luminance measuring device (ILMD). The conditions that are necessary for the proper measurement of GR were also described. The presented method was tested in laboratory conditions and in real industrial environment. Using two laboratory rooms and three different glare sources we created a set of working conditions with different glare sensation. The results of the GR measurements were consistent with the simulation in the DIALux software (mean relative difference of 2.5%). We also conducted tests in six industrial plants at 26 workplaces. In 73% of analyzed cases, the workers' subjective assessment of the glare was consistent with the results of GR measurement. A number of laboratory tests and assessments in real industrial environment confirmed the correctness of the proposed measurement method.