Glare is the biggest lighting problem. The lower the lighting level, the better white light performs.
White light increases peripheral visibility.
Motion detector lights save energy by lighting areas only when someone is present.
Light Emitting Diode (LED) lights are being used in guard rails to light pavement.
The lowest level of light, applied most uniformly is the best lighting. Must rethink the way we do lighting: how we light, what we light and what people need to see.
Candelas per meter squared (cd/m²) measures brightness.
Full moon: 2,500 cd/m²
T-21 Flourescent tube: 8,000 cd/m²
T-8 Flourescent tube: 12,000 cd/m²
Metal Halide: 20,000 cd/m²
Uniformity in lighting has been researched with the following ratios related to detectability:
1:2 Barely detectable
1:3 Still uniform to the eye
1:10 Strong accent
1:100 Adaptation problem
Adjacent properties should never have a contrast ratio higher than 10-times. Can use lowest level area lighting, but destination points (doorways, entrances) need a higher intensity.
Source: Nancy Clanton, PE, Architectural Engineer, Boulder, Colorado