Light Intensity

One of the Dark Sky principles is to have only the amount of light necessary for the purpose, with the idea of limiting the intensity of light.  In contrast, it is natural to assume that more light will give more visibility.  However, observation and research have shown that moderate decreases in light have little effect on visibility.

The US Department of Energy report Pedestrian Friendly Outdoor Lighting from 2013 found that: 

  • Illumination intensity at the low end of the recommended scale was acceptable. 
  • People preferred a soft-edged distribution of light to eliminate sharp bright spots and sharp shadows.  This is referred to as an even light distribution. 
  • People preferred lighting with no glare. 
  • People preferred lighting with a warm color, between 2,700 and 3,000 degrees Kelvin.   

1.07 foot candles:

1.07 foot candles

1.5 foot candles:

1.5 foot candles

2.0 foot candles: 

2.0 foot candles

2.6 foot candles:

2.6 foot candles