Maintenance factor

The maintenance factor is a numerical value that defines the ratio of a maintenance value to the new value of a (physical) variable. It is required for planning and takes into account, for example, wear and tear , soiling and other factors resulting from the use of an object. By definition, a maintenance factor can never be greater than 1.00.

Maintenance factor with light

If lighting systems are planned, a maintenance factor must be agreed between the planner and operator. The factor can also be calculated individually or simply determined by the planner from other information. It describes the light degradation of lamps over the period of use of a lighting system. The minimum lighting requirements stipulated in the standards, the ASR or the AMEV represent the maintenance value of the illuminance . Standards are, for example, DIN EN 12464-1 for indoor workplaces, DIN EN 12464-2 for outdoor workplaces and DIN EN 12193 for sports facilities. For roads own normative requirements apply.

The maintenance factor for a lighting system can be calculated individually for each application using the following formula.

${\ displaystyle {\ begin {aligned} {\ text {WF}} & = {\ text {RWF}} \ cdot {\ text {LWF}} \ cdot {\ text {LaWF}} \\ {\ text {LaWF }} & = {\ text {LLF}} \ cdot {\ text {LLWF}} \ end {aligned}}}$

RWF : The room maintenance factor includes the decline in the reflective properties of the wall surfaces of a room. This is directly dependent on the purpose of the room. For example, an office environment will always be cleaner than a workshop.
LWF : The luminaire maintenance factor describes the influence of pollution on the optical system of a luminaire. The design of a lamp can improve this factor.
LaWF : The lamp maintenance factor can be specified explicitly or calculated from the properties.
LLF : The lamp survival factor (LSF) describes the probability of failure of a lamp. The factor depends on the lamp type and is determined by the manufacturer.
LLWF : The lamp lumen maintenance factor (LLMF) describes the decrease in the luminous flux of a lamp over the service life.

Some of this information is provided by lamp and luminaire manufacturers, others, such as the maintenance interval or an annual usage period, must be assumed in order to be able to calculate the maintenance factor.