Working spaces where visual tasks are only
occasionally performed
10-15-20
Performance of visual tasks of high contrast
or large size
20-30-50
Performance of visual tasks of medium contrast
or small size
50-75-100
Illuminance
on task
Performance of visual tasks of low contrast
or very small size
100-150-200
Performance of visual tasks of low contrast
and very small size over a prolonged period
200-300-500
Illuminance on task, obtained by a combination of general
and local supplementary lighting
Performance of very prolonged and exacting
visual tasks
500-750-
1,000
Performance of very specific visual tasks
of extremely low contrast and small size
1,000-1,500-
2,000
Source: Illuminating
Engineering Society of North America (IESNA) Lighting Handbook Reference
& Application, 8th Edition
Note: Measurements
may be obtained by a light meter (available at lighting supply stores or
camera shops). Selection of the appropriate illumination level from among
the range depends on considerations including occupants' age, speed and/or
accuracy of the task, and reflectance of room or task objects.
