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Allan OttossonDevelopments in Energy-Efficient Lighting Technology Royal Institute of Technology/Vattenfall, Sweden Abstract The purpose of lighting is to provide conditions for good visual performance as well as pleasant and stimulating visual environments. Consequently lighting designers today devote much effort to the creation of lighting installations with high lighting qualities and reasonable electricity consumption. However, lighting solutions have not always been energy-efficient, due both to inefficient lighting components and to inefficient lighting designs. Older lighting installations are therefore often very energy-inefficient. Thus a substantial amount of electricity is today used for lighting, in industrial countries as much as 10-25%. In commercial buildings, the fraction may be as high as 40% - a heavy load on the HVAC systems which further increases the use of electricity. There are many ways of making lighting installations energy-efficient, especially when retrofitting older installations. Over the years, a wide variety of methods have been developed for making lighting more energy-efficient. Achievements in light source technology have resulted in a wide variety of products covering all fields of use. Today's light sources are often highly energy-efficient with good colour rendering and field performance. It is, in many cases, possible to achieve efficiency-gains in the order of 80% by changing a lighting installation from incandescent lamps to CFLs, fluorescent tubes or metal halide lamps. Changing HID mercury lamps in street lighting to high pressure sodium lamps reduces electricity consumption by one third. Electronics have come to play an important role for improved and efficient operation of light sources. This is today especially important in fluorescent lighting, where electronic ballasts make the lamp-ballast system about 20-25% more effective than in the usual 50 Hz magnetic ballast operation. Luminous flux control is also easy to achieve with electronics, giving new possibilities for lighting management using daylight and movement sensors. Electronics also provides hope for effective and intelligent lighting systems, where luminaires can be connected to a bus system in which each luminaire can be individually addressed and controlled. Preferred light settings can be selected and stored in building management computer system and brought into use by the room occupant when needed. Luminaires using optically well-designed and highly effective aluminium reflectors make it possible for the lighting designers to meet the need for good lighting design and high energy-efficiency. But a good lighting design is not enough. The operation of the lighting installation has to be well managed. Maintenance of the installation is also important in order to avoid unnecessary energy losses.
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