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FACILITIES GUIDE | JUNE 2020
Fig. 3. Reference grid for calculation and measurements.
Maintained values
The lighting level provided by an installation will decrease throughout its life, mainly as a result of
depreciation of lamps and luminaires (see also section 7 below).
Average illuminances given in table.5.2 and table 5.3 are maintained values under which the
lighting level should never fall below, during the whole operation of an installation.
Usually a maintenance factor is specified to compensate for ageing and soiling of the light sources,
reflectors and front glasses. In the absence of relevant information, it is recommended to use a
maintenance factor of 0.8.
