Glare must be limited to avoid a decrease in visual performance. In CIE publication 117 "Discomfort Glare in Interior Lighting", the UGR method was stipulated for glare rating (see chapter "Direct glare"). It fundamentally also applies to indoor sports facilities.
The UGR method for glare limitation was developed for working situations with predominantly horizontal viewing direction and for luminaires arranged at the ceiling in regular patterns. In many types of sports, the viewing direction is often directed upwards. This can necessitate additional measures beyond UGR rating for glare limitation in sports halls. For example, the glare risk due to high luminance levels of the light sources in the field of vision of a player at some critical points on the playing field can be reduced using appropriate arrangements and shielding of the light sources.
The luminaires should be installed preferably along the viewing direction, parallel to the long sides of the hall and, if possible, not directly above the hall’s centre line or the playing field, since in this area e.g. ascending balls must be recognised securely and without glare, which may be caused by looking into the luminaires. Due to the required illuminance uniformity, this is not always possible, but it is less problematic in linear luminaires (with diffuse LED modules or fluorescent lamps) due to the lower luminance levels compared to spotlights (with LEDs or high-intensity lamps). However, it must be considered that the viewing direction of athletes changes constantly, while "psychological glare" in work situations is characterised by relatively static viewer positions and viewing directions.