Maintenance factor occurred by the aging or pollution of the lamp. It is the multiplier that expresses the decrease in light output. Maintenance factor refers to the loss of light that occurs over time and is also known as loss factor.
During the operating time of light sources, there can be a slight decrease of light output in other words lumen. In addition of this, pollution of light sources can also cause decreasing of light output. When calculating lighting levels, this decrease from aging and pollution should be taken into consideration.
For all indoor and outdoor lightings, it is not possible to say that the lighting levels remain constant throughout the operating period. Failure of light source and pollution of the light source can cause a decrease of lighting levels in time. If this is an indoor lighting, the reflection on the ceiling and wall of the room will be reduced over time. This will cause a decrease in lighting levels.
Maintenance factors are calculated according to lamp type, maintenance interval, operating time, reflection rates of the room and environmental factors. There is special software developed for this calculation.
It can also be calculated by the formula below;
MF = LLMF x LSF x LMF x RMF
Maintenance Factor: MF
Lamp Lumen Maintenance Factor: LLMF
Lamp Survival Factor: LSF
Lighting Fixture Maintenance Factor: LMF
Room (Surface) Maintenance Factor: RMF or RSMF
LLMF, Indicates a time-dependent decrease in the light flow of the lamp. This value is usually determined by light source manufacturer.
LSF, Indicates the failure status of the lamp. In case of a failure, if the lamp can be changed immediately, this value can be taken as 1. Therefore, the effect can be ignored.
LMF, Indicates the light loss caused by pollution from environmental reasons. For indoor applications, 0,93-0,98 values can be obtained for clear environments.
RMF or RSMF, indicates a time-dependent decrease in the reflection values of room surfaces. This value can be obtained between 0,95-0,97.
Protected light flux can be obtained by multiplying initial light flux and maintenance factor.
Maintenance factor should be taken into consideration when lighting applications done. Values above the minimum light levels specified in the relevant standard must be obtained at the beginning. Loss of light over time should not cause the lighting conditions to fall below the specified criteria.