Lighting Energy Need and Sustainability
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Lighting Energy Need and Sustainability Felix Amankwah Diawuo School of Engineering, University of Energy and Natural Resources (UENR), Sunyani, Ghana
Synonyms Illumination; Radiance
Luminescence;
Luminosity;
Definitions Lighting energy need in general terms can be defined as the integral of the instant lighting loads throughout a given period (e.g., a year, kWh). The amount of light needed within a given space and time to provide a certain level of visual comfort and/or productivity is referred to as the lighting load. Lighting involves both the state of “being illuminated” and a “process of illuminating” a place using an illuminant such as charcoal burners, light bulbs, kerosene lanterns, daylighting, etc. Light forms part of the visible range of the electromagnetic spectrum whose wavelength and frequency distinguish it from other forms of radiant energy such as radio and infrared waves (DiLouie 2011; Lenk and Lenk 2017). The human eye as a physiological sensor can detect and respond to the presence of light,
thus, enabling us to interpret the happenings in our surroundings. Light can be produced in different ways – naturally or artificially. Before the invention of artificial light, the source of light available to humans was mainly through daylight and moonlight which reached the eye after undergoing numerous diffusions and reflections in the physical surroundings before it was seen (IEA 2006). In lighting applications, there are two key measurable photometric quantities, namely, illuminance and luminance. “Illuminance” is a measure of the amount of light falling on a specified surface. Its unit is lux (lx), defined as equal to one lumen per meter squared (1 lm/m2). “Luminance” is a measure of brightness of a specified surface if considered as a large light source. Its unit is candela per meter squared (cd/m2). For simplicity, guidelines for lighting quality usually set out illuminance levels, but it should be noted that the visual system responds to the luminance of the surface brightened by the lighting source, not per se the illuminance. The specified illuminance level is meant to provide an indirect benchmark of lighting effect (IEA 2006). The measure of the quality of light is in part determined by the degree of visibility required for a certain type of activity. The amount of light required for surgery, for instance, might be different from the one required in an office setting. Nonetheless, the quality of light is not only accustomed to the ability to execute a certain visual task, but it incorporates the influence lighting has on health, mood, and alertness.
© Springer Nature Switzerland AG 2020 W. Leal Filho et al. (eds.), Affordable and Clean Energy, Encyclopedia of the UN Sustainable Development Goals, https://doi.org/10.1007/978-3-319-71057-0_45-1
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Introduction For thousands of years, our forebears had to rely solely on sunlight for lighting purposes until about 500,000 years ago when humans first learned how to tame fire which then became conceivable to use light and heat meaningfully (Zumtobel 2018)
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