|Date||March 11, 2019|
The simplest interpretation of providing lighting to a visual task is to provide ‘light’ or illuminance. This leads to a simple but commonly held view that the only solution to any lighting problem is to provide more illuminance.
However, while merely adding more light might provide an adequate viewing environment for simple viewing tasks, such an approach will rarely provide optimum viewing conditions and for more detailed tasks will not meet even basic criteria. While the provision of sufficient illuminance on the task is a necessary element, in many instances task visibility depends heavily on the way in which the light is applied. Critical factors are the luminance contrast of the task and luminance adaptation level of the observer. Further, creation of the comfortable visual conditions which people require in order to maintain efficiency over a period of time depends on factors such as:
Attention to all of these factors produces ‘good quality lighting’. Experience has shown that when inefficiency, eye fatigue, spoilt work or accidents are blamed on the lighting system, failure to meet one or more of the ‘quality’ recommendations is often a significant part of the problem and insufficient illuminance is either a contributing factor only or not an issue at all.