Surrounding of task area
While the correct illumination of the task area is of paramount importance, for the human well-being also its immediate surroundings have to be taken into account. Sudden illuminance drops immediately outside the task area may cause problems to see objects outside the immediate surroundings and cause unnecessary strain and stress. The standards therefore call for the proper lighting of surrounding of the task area.
The EN 12 464-1 defines the surrounding as the band at least half a meter wide around the whole task area. In this band the illuminance has to be at least 66 to 75 percent of the task area illuminance. Higher ratios are meant for lower illuminance areas. If a task area has a minimum illuminance set at 200 lux, the surrounding area has to have at least 150 lux. With higher values the ratio decreases. For the most visually taxing tasks the standard calls for 750 lux while surrounding must have two thirds of that value, only 500 lux.
Again, proper illumination level can be achieved and kept by using sensors and control of luminaires. An intelligent control system can dynamically adjust the illumination level even if task areas are not in constant position and dim or fade up the lights accordingly. And again, lighting systems should be used with overhead in mind as the quality of light sources and their illuminance deteriorates with age.
In the working environments without background natural illumination artificial background lighting has to be provided to keep comfort levels high. Dark walls create negative psychological reactions and background ambient lighting, defined in EN 12464-1, should be used to rectify the situation. The LQS standard once again awards 5 points for compliance with the standard or zero for failure to comply.