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Individual Workplace Lighting How to combine energy-efficiency with optimal visual comfort and work performance
Rob Embrechts
Ing., ETAP NV, Malle, Belgium Wim Slipenbeek Ing., ETAP BV, Breda, The Netherlands Summary The purpose of this paper is to increase awareness of the possibilities of an individual lighting system, especially concerning the energy savings to be obtained while maintaining optimal visual comfort and work performance. Conventional general lighting systems can be energy-efficient if highly optimized reflector designs and control gear are used. Local lighting systems can intrinsically offer energy savings by providing more light only where it is necessary (e.g. the desk) and less light where this is possible (e.g. rest of the room). However, numerous experiments have criticized the currently available local lighting systems, mainly because of their poor ergonomic lighting quality. Neglecting the importance of ergonomics in lighting design would surely lead to false (energy) savings which would have, in the long run, quite the opposite effects. This presentation will show that local lighting can yield substantial energy savings without compromises towards a high ergonomic lighting quality and user-friendliness. For this purpose, a new concept for office lighting has been developed. The concept consists of three components which can be controlled individually by the user. Two components take care of the direct illumination of the task and are related to the desk or task area. The third component is used to light the surroundings, thus creating an ergonomically balanced and pleasant atmosphere in the working room. By dividing the lighting task over three different components, each of their optical systems can be optimized to satisfy its individual needs. In this way, a lot of attention can be given to the ergonomic aspects of a good lighting system. Furthermore the new concept allows the user to adapt his lighting system to his own wishes or demands. This increases the user's decision latitude, which has a favourable psychological impact. This new lighting concept is very energy-efficient, first of all due to a reduction of the installed load in comparison with conventional lighting. Further energy savings can be achieved by the selective use of the three components, e.g. depending on the visual task to be performed. Sine the task component is independent of the surroundings component, a daylight-dependent regulation or an occupancy detection can be used sensibly without the disadvantages that these measures often show in conventional lighting installations. In this way, we can obtain an equally good or even better ergonomic solution than with conventional lighting, combined with total energy savings of up to about 50%! Mainly due to these possible energy savings, this new concept has already attracted a lot of attention from Dutch energy distribution and related companies, such as EnergieNed and the KEMA.
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