The three main considerations for exterior lighting are energy waste, glare, and light trespass. Light trespass, also known as spill light, is light that strays from its intended target and becomes an annoyance or nuisance. Maximizing the utilization of light output where and when it is needed will reduce light trespass. IES recommended light levels makes good economic sense and will minimize adverse environmental impacts associated with light trespass.

Strategies for Exterior Lighting

• Use lighting fixture with directional control.
• Direct and control light output to locations where it is needed.
• Use time controls/dimmers to turn lights on and off and reduce light levels.
• Design and install lighting to minimize glare.
• Use the right amount of light for the task
• Use energy efficient light sources and fixtures.

Environmental Effects

Exterior lighting can also have effects on the environment, excessive lighting near wildlife areas can adversely impact migrating bird life, nocturnal insects and other species. State and local ordinances have been established to protect natural wildlife from light pollution.

Ordinances and Community Standards

Outdoor lighting ordinances and codes encourage better quality lighting, which reduces glare, light trespass, and energy waste. Many codes are now including the concept of E-zones to distinguish between different types of lighting areas. For example, near national or state parks, wildlife refuges, or astronomical observatories lighting levels should be much lower than in city centers. The ordinances and community standards vary and local zoning departments should be contacted before implementing an outdoor lighting project.