Lighting quality depends upon both physical and psychological parameters. Good lighting quality exists when a lighting system:
Lighting quality is not inherent in a space or a lighting design, but in its effects on people. It cannot be measured, but as listed above, it is linked to the ambiance and both visual comfort and performance. Each of these three parameters can be developed as shown in the figure below.
Those factors have lots of interactions between them. Especially visual comfort and performance, since they can both be impaired by a phenomenon called glare. According to the international vocabulary of lighting, glare results from conditions of vision in which there is discomfort or a reduction in the ability to see details or objects, caused by an unsuitable distribution or range of luminance, or to extreme contrasts.