Visibility

Visibility is defined by:
   Lighting Levels (foot candles are the standard of measure)
   Uniformity
   Luminance (brightness)
   Glare

Foot Candles (fc) can be visualized as follows:

Full moon: 1/100th fc (.01 fc)

Street lighting: 1.0 fc

Big Box Retail (Parking Lot): 10.0 fc

Gas Station: 100.0 fc

A typical office situation is designed for 30.0 fc

Douglas County, Colorado has an ordinance that carries a maximum of 10.0 fc everywhere and there are no variances. 

Over-lighting is expensive. 2.0 fc consumes two times the energy of 1.0 fc. Quality lighting related to light levels can generate tremendous energy savings. 

Source: Nancy Clanton, P.E. Architectural Engineer, Boulder, Colorado