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> Indoor lighting / General requirements / Maintenance Factor / Maintenance Factor due to reference values of light sources, luminaires and the surrounding room
Generally, the maintenance factor can be determined using the following formula with the respective data of lamp and luminaire manufacturers or data from reference curves.
MF = LLMF · LSF · LMF · RMF
This procedure is described in detail in the publication CIE 97.2:2005 titled "Guide on the maintenance of indoor electric lighting systems". According to EN 12665, the terms used here are defined as follows:
The maintenance factor MF is the ratio of the average illuminance on the working plane produced by the lighting installation after a certain period to the average illuminance produced by a new installation under the same conditions.
The lamp lumen maintenance factor LLMF is the ratio of luminous flux of a lamp at a given time in the life to the initial luminous flux.
The lamp survival factor LSF is the portion out of the total of lamps which remains ready-to-operate at a given time under specified conditions with a defined switching frequency. In LED luminaires, it is mostly determined by total failure of the LED luminaire (see chapter ).
Luminaire maintenance factor LMF is the ratio of the light output ratio of a luminaire at a given time to the initial light output ratio (luminaire light output ratio). For LED luminaires, the initial luminaire light output ratio is LOR = 1.
The room surface maintenance factor RSMF is the ratio of the light reflected by the surfaces of a room after a certain period of use of the lighting installation to light reflected when the installation is considered conventionally as new. The room surface maintenance factor according to EN 12665 describes merely the change in reflectance value of the room surfaces. It causes no change (decrease) of illuminance on the working plane proportional to it, since the direct portion of the light as well as multiple reflections occur.
The room maintenance factor RMF captures the change in utilance U during the period of operation. Utilance therein describes the dependence of the illuminance on the working plane due to the deterioration in surface reflectance with consideration of the direct portion of light and the occurring multiple reflections.
Maintenance Factor Lamp Maintenance Factor of an LED luminaire
Maintenance Factor due to reference values of light sources, luminaires and the surrounding room Lamp Maintenance Factor of an LED luminaire Luminaire Maintenance Factor Room Maintenance Factor Example for the determination of the maintenance factor due to technical data of LED luminaires and the specification of the room Lamp Maintenance Factor of a fluorescent lamp Example for the determination of the maintenance factor due to reference values of fluorescent lamps, luminaires and the room Reference Maintenance Factors
Introduction Visual needs Need for orientation Non visual needs
Guidelines Overview Work places Visual task area Surrounding area Illuminance Luminance distribution Limitation of glare Lighting direction, modelling Aspects of colour Flicker and stroboscopic effects Daylight
Maintenance Factor Light and safety at work Light and non-visual effects Light and economy Light and environment Lighting design Lighting measurement Emergency lighting
Lighting of traffic zones and geneal areas in buildings Lighting of industrial activities and crafts Lighting of offices and VDU workstations Lighting of design and CAD offices Lighting of sports facilities Lighting of health care facilities Lighting of geriatric care facilities and nursing homes Lighting of public areas Lighting of salesrooms Lighting of educational facilities Lighting of traffic areas Lighting of car parks Ligthing of further indoor spaces
Luminaires The enhanced concept of quality Photometric classification Photometric properties Photo biology safety Mounting and electrical connection Luminaire labelling Luminaire operation LED luminaire operation Operation of FL luminaires Electrical safety Fire protection Electromagnetic safety Mechanical safety Chemical and miscellaneous impact Acoustic properties Ventilation properties
Firehazardous locations Room with bathtubs and showers Swimming baths Exterior installations Agricultural and gardening plant locations Food industry Clean rooms Requirements on mediacal rooms Emergency light installations
Luminaire selection chart
Light management application and function Presence detection Daylight-dependent regulation Interfaces Building management, KNX and other bus systems
Light sources types Characteristics of light sources
ABC, DF, G, ILM, NO, P, QRSUV, W
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