According to EN 12464-1 the designer must specify the maintenance factor which serves as the basis of planning and to document all assumptions made for its determination, including the maintenance plan. In practice, this is not always possible, which means that reference values for the maintenance factor must be used and documented including the parameters associated with it (see also chapter "Conservation of the lighting level (maintenance factor)").
By utilising advanced lamp, control gear and luminaire technologies as well as selecting functional reflectance when it comes to room boundary surfaces and furniture, the designer can optimise the lighting installation regarding maintenance factor, maintenance intervals and thus investment and operating costs. Where pertinent data is lacking or project estimates are desired, the following reference values for the maintenance factors can be used.
Given the conditions of
very clean non-smoking offices,
frequent and intensive cleaning of rooms as well as
a three-year maintenance cycle
or comparable applications, a maintenance factor of 0,8 can be assumed, provided that
tubular tri-phosphor fluorescent lamps with very limited decreases in luminous flux over the period of use,
electronic hot-start control gear for highly lamp-preserving starting,
state-of-the-art luminaires, e.g. specular louvre luminaires with compacted reflecting surfaces or luminaires open towards the top and the bottom with circulation of air and low levels of dust accumulation,
or LED luminaires with reduced luminous flux decrease, e.g. L85 (see also chapter "The lamp maintenance factor of an LED luminaire")
In other cases, the reference maintenance factor 0,67 for offices and comparable applications should be used as a rule.
Details on determining the maintenance factor see chapter "Maintenance factor".