Determining Desired Light Level

Light and contrast work together to provide a perceived brightness.  Overlighting dilates the eye and, essentially, light energy is wasted.  A high contrast style of lighting will make the "hot spot" appear brighter than that same level spread uniformly over an area.  Conversely, less light can seem brighter if it is distributed uniformly with no adjacent hot spots. 

For ambient lighting, uniformity (the minimization of contrast) provides a comfortable environment, minimizes eye strain, and increases perceived brightness.  If this is your objective, the following guidelines can be used to determine how much light you need.

There are numerous sources of recommended lighting levels for specific locations.  The American Institute of Architects (AIA) is a recognized source, as is the Illuminating Engineering Society of North America (IESNA).  We use their guidelines to recommend minimum lighting levels to our customers and to develop our luminaire designs: 

Activity
Illumination (lux)
Illumination (fc)
Parking Garages, Street Lighting
10
1
Warehouses, Homes, Theaters, Archives

150

15

Easy Office Work, Classrooms

250

25

Normal Office Work, Library, Supermarket, Showroom, Laboratory

500

45

General Mechanical Workshop, Precision Manufacturing

750

70

Detailed Mechanical Workshop, Athletic Performance Facility

1000

95

Detailed Drawing Work, Very Detailed Mechanical Work, Operating Room

1500+

150+

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