Strategic Office Lighting

Abstract

Lighting design in office buildings is determined by basic human needs, such as visual comfort, visual performance, and visual safety. This chapter compiles indices to evaluate the luminous quality, visual comfort, and performance in the built environment. Illuminance-based indices are used to arrive at threshold values of a luminous environment to consider as comfortable. Indices related to glare and colour rendering indicate visual performance regarding whether a physical quantity matches to a reference value. Indoor daylight performance is evaluated by assessing the indoor daylight availability and artificial lighting by field measurements, software simulation and estimating energy implication. Daylighting fundamentals, such as daylight illuminance, spatial daylight autonomy, the intensity of visual comfort, are described. The suitable colour scheme has positive effects on human emotions, work performance, and productivity. Indices indicating the colour rendering properties of a light source are the CIE colour rendering index, gamut area index, feeling of contrast index. The phenomenon of glare defines the sensation produced by luminance within the visual field that is much higher than the luminance eyes can adapt, and thereby cause annoyance and visual discomfort. Direct glare occurs due to light sources within the field of vision, whereas indirect glare may result from reflections of light sources or surfaces of excessive brightness, and veiling glare from polished, shiny or glossy surfaces, computer screens. The glare indices, such as British glare index, CIE glare index, discomfort glare index, visual comfort probability index combine the contrast between the luminance of glare source to that of background luminance, about the position of the observer.