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Luminaire efficiency factor system for general lighting

Axel Stockmar, LCI Light Consult International, Germany


general lighting, luminaire efficiency, utilisation factor, European utilisation factor method, European luminaire efficiency labelling system


Lighting requirements concern the criteria illuminance level, luminance distribution, glare limitation, modelling, colour appearance, and colour rendition. Besides these photometric quality criteria special attention is paid to the costs for acquisition, installation, maintenance, and operation of the illumination. Here it is of particular interest to what extent the total costs could be reduced by utilising lamps with higher efficacy, ballast with lower losses, and luminaires with higher light output ratios and more appropriate luminous intensity distributions.

For lamps and ballasts appropriate classification and labelling systems have been developed and are in use throughout Europe. For luminaires there are a number of proposals for energy-dependent classification and/or labelling procedures, but for various reasons non of the methods has been developed towards a usable system.

As luminaires are being designed to fulfil particular needs, it seems to be impossible to create a system which would cover all luminaires.

However for luminaires to be used for general lighting of e.g. offices, stores, workshops, sports facilities etc. a luminaire efficiency factor system could be developed based on an utilisation factors.

As the utilisation factor is in proportion to the light output ratio and is dependent on the luminaire flux distribution, the luminaire layout, and the reflection properties of a space, it is necessary to define appropriate standard conditions.

Concerning the luminous flux distribution there is a need for more than one category, i.e. direct/semi-direct, direct/indirect, and semi-indirect/indirect. To keep the system simple there should be only a few standard rooms, but with two luminaire arrangements for ceiling mounted and suspended installations. The reflectances of ceiling and walls should be suitable also for luminaires with considerable upward flux components. Based on a comprehensive European utilisation factor method a luminaire efficiency factor labelling system for general lighting will be discussed.


Download this paper as pdf: RL5_Stockmar.pdf