This document discusses the problems of light trespass and light pollution from outdoor lighting. It defines light trespass as unwanted light falling beyond the intended area, which can cause spill light and brightness issues that negatively impact neighbors and drivers. Common offenders are street lights, sports fields, and commercial lighting using excessive lamps. Solutions include using luminaires that control light above the horizontal plane like cut-off designs, shields to reduce reflections, and reviewing lighting systems. The document also discusses how light pollution affects the environment and sea turtles and birds, and how the LEED program addresses light pollution reduction.

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