3 Lighting Design Practices to Reduce Light Pollution

Southern Landscape Lighting Systems of Alpharetta explains the dangers of light pollution and outlines how landscape lighting designs can minimize its effects.

A key issue facing the outdoor lighting industry, both commercial and residential, has to do with light pollution. A term first used in 1968, light pollution is a 20th-century phenomenon resulting from the oversaturation of light in densely populated cities. Lighting accounts for 25% of all energy consumption worldwide. There are over 16 million external public lights in the United States and exterior residential lighting numbers over 1 billion units. The large-scale adoption of LED has dramatically reduced energy consumption from lighting.

There are effective efforts to adequately manage and minimize light pollution. Industry professionals, especially residential landscape lighting specialists, are paying attention to concerns about light pollution and light trespass, a particular concern to residential lighting designers because of the close proximity of so many homes.

What is light pollution?

One definition of light pollution is the “brightening of the night sky caused by streetlights and other man-made sources, which has a disruptive effect on natural cycles and inhibits the observation of stars and planets.” Light pollution is described as excessive, misdirected, or obtrusive artificial – usually outdoor – light. Light pollution occurs when there is an over-saturation of light, such as in large cities.

Three Main Types of Light Pollution

There are three main types of light pollution – glare, light trespass, and skyglow.

• Glare: The source of glare is unshielded lighting.  When unshielded light enters the eye, it can cause a loss of contrast, which temporarily distorts vision and can lead to unsafe driving conditions that may result in a car accident. 
• Light trespass: Light trespass is when unwanted light invades another person’s property. An example of this would be when a streetlight or spotlight shines through the window of a person trying to sleep. 
• Skyglow: Skyglow refers to the glow effect that can be seen in overpopulated areas. It is the combination of reflective and upward-directed unshielded light escaping up into the sky.

Effects of Light Pollution

The natural diurnal patterns of light and dark orchestrate the rhythm of life. Disrupting these patterns impacts the ecological dynamics of nature in the following ways:

• Confuses nocturnal wildlife
• Negatively impacts plant and animal physiology
• Confuses the migratory patterns of animals
• Alters competitive interactions of animals
• Changes predator-prey relations
• Disrupts circadian rhythms and the production of melatonin in humans
• Causes sleep disorders and resulting fatigue
• Contributes to increased frequency and intensity of headaches
• Increases stress and anxiety

When planning any outdoor lighting project, consider the three following basic guidelines:

1. Select dark sky friendly light fixtures that cast the light only where it is needed.

To minimize light pollution from pole-mounted area lighting and wall-mounted security or decorative lighting, choose fixtures the manufacturer specifies as “full cutoff.” These fixtures will direct the light toward the ground where it is needed and not allow light to escape into the night sky.

2. Select light bulbs for the fixture that produce an appropriate level of brightness.

Residential outdoor lights are known for brightness levels that cause glare and detract from the appeal of the lighting. Warmer color temperature lights (2700K to 3000K) produce gentler, more pleasing effects. Even where whiter light is desired, the lumen output should be chosen at the lowest level that accomplishes the purpose of the light fixtures. This may require experimenting with different wattage bulbs.

3. Minimize blue light emissions by using 3000K color temperature or lower.

With the increasing use of LED and metal halide light sources for outdoor fixtures, blue wavelength light has raised concerns. Metal halide bulbs, which are often found in streetlights and area lights, tend to produce light with a strong blue wavelength. LEDs are available in a broad range of color temperatures from warm white to very bluish-white light.

Light pollution is a concern, especially in congested population centers. Following some thoughtful design, guidelines go a long way toward reducing glare, light trespassing, and sky glow. The team at Southern Landscape Lighting Systems of Alpharetta takes light pollution seriously. Their designs and installations take into consideration the impact of outdoor landscape lighting on the environment.

For more information about landscape lighting design, contact the Southern Landscape Lighting Systems of Alpharetta at (770) 691-1221. Visit them on the web at https://southernlls.coma/locations/alpharetta-georgia.

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