Summer, under a cloudless sky, in the open 100,000 Lux
Summer, under a cloudless sky, under a tree 10,000 Lux
In the open, under a heavily overcast sky 5,000 Lux
Indoors by the window, shaded, clear day 2,000 Lux
Indoors away from the window 300 Lux
Full moon, in the open, on a clear night 0.25 Lux
The target illuminance for an interior space depends on the specific visual tasks carried out in the space and can be anything from hundreds to thousands of Lux.
100 Lux interiors used occasionally with visual tasks confined to movement and for only limited perception of detail.
200 Lux interiors occupied for long periods, or for visual tasks requiring some perception of detail.
