1. Electrical Breakfast
Club
03/14/08
Light Trespass & Light Pollution

2. INTRODUCTION
 There
is an increasing concern for the problems
created by unwanted light at night.
 Lighting designers are faced with conflicting
challenges
Meeting Local ordinances controlling the light
 Meeting the needs of having the light


3. PROBLEMS
 Light
Trespass
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.
 Discomfort glare
 Disability glare – Reduction in the visibility of significant
visual tasks


4. PROBLEMS

Who does light trespass having the largest negative
impact on?
Neighborhood residents
 Unwanted light shining into homes at night
 Desire to have a low level of ambient light
 Drivers
 Disability glare can seriously affect a driver’s visibility
and ability to locate and recognize signal lights.


5. PROBLEMS

Biggest Offenders
Street lights with inadequate optical control
 Sports field lighting
 Commercial lighting


Biggest Reasons
Excessive and unnecessary use of lamps with light lumen
output
 Incandescent floodlights improperly aimed
 Luminaires left on all dusk to dawn for no real purpose


6. PROBLEMS
 Light
Pollution
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.
 General Public
 Astronomy

7. PROBLEMS

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.

8. ENVIRONMENTAL AFFECTS
 Environmental

Sea Turtles


Affects
Illuminated beaches
Birds
Nighttime illuminance confusion
 Death spiral


9. SOLUTIONS

Luminaires that allow for control of light above the
horizontal plane.
Semi-cut-off
 Cut-off
 Full cut-off

Luminaire shields
 Reduce amount of light on highly reflective
surfaces.
 Review lighting systems


10. LEED

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.

11. EXAMPLES

12. EXAMPLES

13. EXAMPLES