Although the cost of energy for lighting is substantial, it is small compared with the cost of labor. Therefore, these gains in productivity may be even more valuable than the energy savings associated with new lighting technologies. In retail spaces, attractive and comfortable lighting designs can attract clientele and enhance sales. Three quality issues are addressed in this section. Perhaps the most important factor with respect to lighting quality is glare.
Glare is a sensation caused by luminances in the visual field that are too bright.
Discomfort, annoyance, or reduced productivity can result. A bright object alone does not necessarily cause glare, but a bright object in front of a dark background, however, usually will cause glare. Contrast is the relationship between the luminance of an object and its background. Although the visual task generally becomes easier with increased contrast, too much contrast causes glare and makes the visual task much more difficult. You can reduce glare or luminance ratios by not exceeding suggested light levels and by using lighting equipment designed to reduce glare.