Overview

When implementing good lighting, in addition to the required illuminance, further quantitative and qualitative quality criteria must be considered. They are derived from human needs for

• visual comfort which supports well-being and readiness to perform,

• visual performance which facilitates executing the visual task even under difficult conditions, as well as

• safety and integrity.  

The most important quality criteria for lighting are:

• Illuminance 

• Luminance distribution 

• Direct and reflected glare 

• Light colour and colour rendering index 

• Daylight 

• Flicker 

• Light direction 

• Variability of light in terms of level, colour and distribution.

The compliance with said criteria is the precondition for the visual performance required by the visual task as well as visual comfort. Only when considering all quality criteria, can a lighting installation fulfil the set requirements. According to type and difficulty of the visual task, or according to room type, one quality criterion may be prioritised above others.