ABSTRACT
Light, whether it originates from the natural source, the sun and the sky, or from artificial, man-made sources such as candles or electric lamps, is utilized to make the indoor environmental space sufficiently luminous for a variety of purposes from working to resting indoors. This chapter focuses on the fundamental phenomena with respect to the physical characteristics of visible light. It discusses indoor lighting and how it works and affects human perception and resulting behaviour, which affects how the “exergy” resources for lighting is utilized. The chapter schematically demonstrates the change of electric field together with the change of magnetic field to be observed as a wave phenomenon. It also demonstrates an example of the distribution of spectral irradiance, the rate of energy carried by electromagnetic wave per unit length of wavelength, which is incident on a surface having the area of one squared meter. The chapter presents the variation of luminous environment and perception of brightness.
