Loss of illuminance caused by ageing and contamination in a lighting system can be anticipated in the planning phase with the help of design factor p. This means that more "light" is installed at the beginning of the service life of a new system, so that required service illuminance can be guaranteed over a longer period of time.
For interiors subject to normal levels of contamination, a design factor of 1.25 is usually applied. If above average contamination is to be expected or maintenance costs will be high, the design factor can be increased as required. The following design factors are listed in EN 12464 Part 1:
The reciprocal value of the design factor is the maintenance factor v.
For interiors subject to normal levels of contamination, a design factor of 1.25 is usually applied. If above average contamination is to be expected or maintenance costs will be high, the design factor can be increased as required. The following design factors are listed in EN 12464 Part 1:
|
|
Maintenance factor |
Design factor |
|
Reduction in illuminance due to contamination and ageing in lamps, luminaires and interiors |
v |
p |
|
normal |
0,8 |
1,25 |
|
high |
0,7 |
1,43 |
|
very high |
0,6 |
1,67 |
The reciprocal value of the design factor is the maintenance factor v.