ITF

52 FACILITIES GUIDE | JUNE 2020 KEY TERMS Horizontal illuminance This is the amount of light falling on the court surface; it is often referred as lighting level. It is expressed in lux (or foot-candles in the USA). E h average is the average value of the horizontal illuminance calculated/measured on the reference grid. Uniformity of illuminance This is a parameter describing how evenly light is distributed over the court surface. E min /E h ave. is the minimum value of the horizontal illuminance calculated/measured on the reference grid divided by the average value. Glare This is the disturbing effect which impairs the vision; it depends mainly on the ratio between the direct brightness of a lighting installation and the brightness of the court surface. GR is the Glare Rating factor assessing the quality of the installation from a glare perspective Colour temperature This is the apparent colour of a light source; it is expressed in Kelvin (K). Colour rendering Colour rendering describes the ability of a light source to reveal and reproduce colours accurately. It is ranked by the colour rendering index Ra (from 0 to 100) where the higher the index the better the colour accuracy Obtrusive light Spill light, which because of quantitative, directional or spectral attributes in a given context gives rise to annoyance, discomfort, distraction or reduction in the ability to see essential information. In the case of outdoor sports lighting installation obtrusive light is considered around the installation and not for spectators, referees or players within the sports area.

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