2. INTRODUCTION
ď¨ There
is an increasing concern for the problems
created by unwanted light at night.
ď¨ Lighting designers are faced with conflicting
challenges
Meeting Local ordinances controlling the light
ďŽ Meeting the needs of having the light
ďŽ
3. PROBLEMS
ď¨ Light
Trespass
Also known as âobstructive lightâ, defined as
unwanted light that falls beyond the property line or
area intended to be illuminated.
ďŽ Results of light trespass
ďŽ
Spill Light. Lighting areas beyond the area intended to be lit.
Producing illuminance outside of the property lines.
ď¨ Brightness. Bright sources within the observerâs field of view,
such as direct viewing of luminaires.
ď§ Discomfort glare
ď§ Disability glare â Reduction in the visibility of significant
visual tasks
ď¨
4. PROBLEMS
ďŽ
Who does light trespass having the largest negative
impact on?
Neighborhood residents
ď§ Unwanted light shining into homes at night
ď§ Desire to have a low level of ambient light
ď¨ Drivers
ď§ Disability glare can seriously affect a driverâs visibility
and ability to locate and recognize signal lights.
ď¨
5. PROBLEMS
ďŽ
Biggest Offenders
Street lights with inadequate optical control
ď¨ Sports field lighting
ď¨ Commercial lighting
ď¨
ďŽ
Biggest Reasons
Excessive and unnecessary use of lamps with light lumen
output
ď¨ Incandescent floodlights improperly aimed
ď¨ Luminaires left on all dusk to dawn for no real purpose
ď¨
6. PROBLEMS
ď¨ Light
Pollution
Also known as âsky glowâ, defined as light that is
directed upward to the sky or reflected from surfaces
that is interference.
ďŽ Results of light pollution
ďŽ
ď¨
Natural and manmade particles in the air scatter light rays
from outdoor lighting and create an artificial fog in the sky.
ď§ General Public
ď§ Astronomy
7. PROBLEMS
ďŽ
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.
9. SOLUTIONS
ďŽ
Luminaires that allow for control of light above the
horizontal plane.
Semi-cut-off
ď¨ Cut-off
ď¨ Full cut-off
ď¨
Luminaire shields
ďŽ Reduce amount of light on highly reflective
surfaces.
ďŽ Review lighting systems
ďŽ
10. LEED
ďŽ
Light Pollution Reduction Credit
ď¨
ďŽ
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.