In large work spaces as often occur in industrial work places, it is especially important to observe a balanced brightness distribution in the field of vision. The difference in luminance between the bright visual task area and its close surroundings should be no greater than 10 : 3, and that between the visual task area and distant surroundings (background area) no greater than 10 : 1. For background lighting see chapter 3 "Lighting quality criteria".
A balanced luminance distribution in the field of vision is important for the following reasons:
Continuous shifting of the view between the visual task and a work space that is too dark requires adaptation of the eye, which constitutes a visual burden and gives rise to discomfort. The consequences are a lack of concentration, visual defects and work errors as well as premature fatigue.
In the case of serious variations in luminance, danger from the environment, e.g. approaching vehicles or overhead cranes with loads etc. in industrial halls may not be recognised in time, rendering timely reactions impossible. A bright overall work space significantly contributes to occupational health and safety.
Bright work spaces improve communication with both team and work environment and thus promote well-being, motivation and productivity.
Based on the luminance ratio of 10 : 1, which should not be undercut between the visual task and distant, extensive areas, a table for required illuminance on these distant, extensive areas was determined (see fig. in chapter "Lighting quality criteria", section "Luminance distribution"). When designing lighting, these values must be implemented using a suitable lighting concept and an appropriate luminaire arrangement.