Light Trespass & Light Pollution
is an increasing concern for the problems
created by unwanted light at night.
Lighting designers are faced with conflicting
Meeting Local ordinances controlling the light
Meeting the needs of having the light
Also known as “obstructive light”, defined as
unwanted light that falls beyond the property line or
area intended to be illuminated.
Results of light trespass
Spill Light. Lighting areas beyond the area intended to be lit.
Producing illuminance outside of the property lines.
Brightness. Bright sources within the observer’s field of view,
such as direct viewing of luminaires.
Disability glare – Reduction in the visibility of significant
Who does light trespass having the largest negative
Unwanted light shining into homes at night
Desire to have a low level of ambient light
Disability glare can seriously affect a driver’s visibility
and ability to locate and recognize signal lights.
Street lights with inadequate optical control
Sports field lighting
Excessive and unnecessary use of lamps with light lumen
Incandescent floodlights improperly aimed
Luminaires left on all dusk to dawn for no real purpose
Also known as “sky glow”, defined as light that is
directed upward to the sky or reflected from surfaces
that is interference.
Results of light pollution
Natural and manmade particles in the air scatter light rays
from outdoor lighting and create an artificial fog in the sky.
Even light from well-designed lighting systems will
reflect from objects being illuminated and light will
enter the atmosphere. Almost impossible to
eliminate all light from entering the atmosphere.
Luminaires that allow for control of light above the
Reduce amount of light on highly reflective
Review lighting systems
Light Pollution Reduction Credit
Must provide cut sheets of all luminaires along with a
plan showing horizontal and vertical footcandles.
Projects attaining this credit saw an average of
30% electricity savings due to elimination of
luminaires and reduction in lumens.