The following the table shows correction factors for cases where the normal recommeneded illuminance levels can not be applied:
| Case | Correction factor | ||
|---|---|---|---|
|
|
|
| |
| Age of
work force in years |
|
|
|
| Reflectance
of near surrounding |
|
|
|
| Speed
and accuracy of perception |
|
|
|
Adjusting the recommended illuminance levels
For each of these cases, the correction factors are summed up. If their total is -3 or -2, the lower illuminance is used. For a weighting factor of -1, 0, or +1, no correction needs to be applied. A total of +2 and +3 means the conditions are rather poor, so more light is needed. Most countries have their specific interpretations of these CIE recommendation. They can be found in the national codes of practice.
In rooms that have multiple use such as a general office in which technical drawings are made as well, it is not necessary to have the higher recommended illumiance in the entire room. Instead, the room can be split up into different areas. Also, it is often wasteful to produces the required lux level with a general lighting system. Localised task lighting can be far more efficient and people often prefer it because they can adjust it individually.