Discomfort glare: a formula to bridge differences

Abstract

The international glare situation is unsatisfactory: methods adopted in different countries give discrepant predictions. To break the deadlock a rational glare formula is proposed, based on the best information available. The formula allows for luminances, solid angles and positions of glare sources in a similar way as existing formulae, but takes account of the increase in glare experienced when glare sources are added in a room in spite of the correspondingly increased adaptation level. This is allowed for by separating the direct and indirect vertical illuminances at the eye and inserting them suitably into a 'co-variance/adaptation' factor.