Energy Efficient Lighting of nZEB

Abstract

Human beings gather more than 80% of their information about their surroundings by visual perception. The information that we receive is influenced by the characteristics of the light source, the optical properties of objects reflecting the incoming light into the surrounding space, and the way we perceive light by sight and visualise “what we see” in our brain. Light is electromagnetic radiation with wavelengths that can be perceived by human vision. Such radiation is emitted from the emitter with sufficiently high temperature in the case of daylight or incandescent lamps, by electricity-excited gas atoms and molecules in the case of low and high pressure discharge lams, by photoluminescence (the process of emission of light after absorption of nonvisible electromagnetic radiation in the case of fluorescent lamps or by electroluminescence), of the process of the emission of light after the recombination of electrons and electron holes in light-emitting diode (LED). LED technology has proven to be so efficient, so long lasting, and with such large possibilities of adaptation to users and daylight that almost no other electricity source of light is in use for lighting of buildings nowadays. While light has great influence on our health, wellbeing and productivity, this chapter focuses on the energy aspect of indoor lighting. Although extraordinary increases in the energy efficiency of artificial light sources has been achieved, the goal of designers should be focused on daylighting, which is the most acceptable and pleasant way of illumination for people. As up to 30% of delivered energy for the operation of the office and commercial buildings is still needed for lighting, the efficient combination with daylighting and advanced controlling of artificial lighting must be provided in nZEB. Additionally, visual comfort indicators are included in building assessment schemes, such as BREEM or DGNB (see Chap. 14).