How much light is required, account must be taken of the type of visual task, When you are going to make a lighting planing for your room.
To be able to safely find the emergency exit in a building, 1 lx is sufficient
To be able to distinguish facial expressions, approx. 20 lx is required
For accent lighting in shop windows, 1500 – 2000 lx is usual
Operation tables must be illuminated with a minimum of 5000 lx
In rooms where people work, legal minima apply for the illuminance, depending on the room and on the visual task.
Examples from European standard EN12464, Lighting of Indoor Work Places:
50 lx stable
75 lx parking area
100 lx storage space
200 lx canteen
300 lx classroom
500 lx professional kitchen
750 lx fine assembly work
2000 lxengraving installation
5000 lxoperation table
These minima relate to the average illuminance in the working area. The uniformity in the working area may not be less than 0.7, and not less than 0.5 In the immediate surroundings.
The initial illuminance values must be higher than the legal minima, because account must be taken of light degradation caused by contamination and ageing of lamps and fixtures.