Do Your Part to Ward Off Light Pollution


(Thursday, May 15, 2008 3:00 PM EDT)

If a beautiful landscape surrounds your home, it makes sense that you'd want a lighting design to show it off. Just remember, the lights could be illuminating areas beyond your property.

Light pollution (excessive or obtrusive light created by humans) can be created by residential light sources and can make the night sky hard to enjoy, as well as negatively affect the behavior patterns of animals.

How do you keep your lighting design from causing light pollution?

Mark Oxley, a lighting professions with Outdoor Illumination, located in Bethesda, Md., has a few tips.

“For landscape lighting, the first rule of thumb is ‘less is more',” he said in a recent interview. “Less wattage can create dramatic effects in areas where light does not have to compete with existing ambient artificial light.”

One way to “do less” is to use a lower-watt bulb. Instead of using a 90-watt PAR 38 incandescent lamp, a 20-watt infrared MR-16 lamp cold be used to create the same effect, Oxley said.

Other bulbs to use for less-invasive outdoor illumination include 20- or 35-watt infrared halogen lamps, as well as other light sources, such as LEDs, which usually are under 10 watts.

Using timers and light-sensitive photo cells also are vital in an ecologically conscious lighting design.

“Timers are best. A photo cell combined with a timer is even better,” Oxley said. “The photo cell turns the lights on [when it gets dark] and the timer sets the lights to go off, generally at 10 p.m., 11 p.m. or midnight. A photo cell alone will have the lights on all night.”

Another way to avoid light pollution when creating a home landscape lighting design is to avoid up-lighting (lights placed on the ground and positioned upwards).

“Down-lighting from above is a more natural effect and causes virtually no light pollution,” Oxley said. “All light is absorbed below, rather than spilling up towards the sky.”

However, if up-lighting is essential to the lighting design, measures can be taken to avoid excessive light pollution.

Shrouds (extensions at the end of lights) and baffles (waffle-like lenses inside the lights) are used to prevent glare and light spill.

Making sure lights are placed on an angle and illuminate specific objects also is important. “If you try to light everything, you light nothing,” Oxley said. “In Middleburg, it looks to me that people want their landscapes to look natural. If their landscapes look that way, then their lighting landscapes should, as well.”

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