The Future of Electricity
Reducing light pollution can save energy
Lighting the outdoors improves safety and can add drama to your yard and garden. Astronomers, however, don’t think it’s such a bright idea.
Those different points of view have generated a new movement and industry to use outdoor light more efficiently.
Landscape lighting designers believe that artificial lights to show off the features of homes, gardens, and other outdoor spaces are an appropriate and desirable use of electric energy. They think more light after sunset is better. (Kentucky Living, “Illuminating the Outdoors,” March 2004.)
Astronomers and “dark sky” citizen activists believe that outdoor artificial light should be kept to a minimum so that the stars, our Milky Way galaxy, and other features of the night sky remain visible for everyone to enjoy. They think less light after sunset is better.
The dark sky discussion even has its own terminology.
Light trespass occurs when one person’s outdoor lighting affects someone else in an unwanted way, “trespassing” on nearby property, such as a poorly placed streetlight shining into the bedrooms of nearby homes.
Light clutter occurs when conflicting lighting, often a combination of both streetlights and signs, sends confusing messages. Is the entrance under the brightest light, or over there by the sign?
Glare sometimes results from the direction a light is aimed; a light aimed too low hits you right in the eyes. Glare can also occur because the artificial light is bouncing off nearby reflective surfaces.
Light that does not serve its intended purpose, that spills outward and often upward from badly designed, inefficient, or poorly positioned fixtures, is called light pollution.
While urban sky glow (the upward gleam from thousands of light sources in larger cities) is probably the most easily recognized form of light pollution, the skies over suburban and rural areas are beginning to glow, too, obscuring the view of once-familiar celestial objects.
Photo galleries of landscape lighting companies offer breathtaking views of entire houses illuminated by bulbs placed at various angles, including some at ground level. The light washes over attractive patterns in bricks or stone—but a lot of that light misses the building entirely and goes skyward.
The same thing happens with lights sunk in the ground under trees. In winter, the bare limbs catch part of the light—but the rest goes right through the open spaces and into the night sky.
Becoming aware of wasted light is like noticing wasted water. You’ve probably seen a lawn sprinkling system that splashes water onto pavement, or operates when it’s raining. Once you start looking for wasted light, it’s just as easy to find. The next time you drive along a highway, take a closer look at the lighting on billboards and other signs. How much light is on the sign—and how much is spilling over onto trees or the ground below? How much is going straight up into the night sky?
Landscape lighting sales people typically pitch their products by mentioning that the electricity to power their designs only costs pennies per night. But pennies add up. How much of that cost is wasted because the light is too bright for the purpose, poorly aimed, or operating when there are no people around to need it?
Since the late 1980s, several dark sky citizen action groups have sprung up around the world. Astronomers first led these groups as their nighttime observations became more and more difficult with the intrusion of artificial light. Now the membership of these groups is a wide cross section of interested folks from all walks of life.
These concerned citizens are not against all night light. They advocate illuminating only what needs to be lit, when it needs to be lit, and with the right amount of light. Doing so will make it easier to once again see the natural beauty of the night skies—and save electricity, too.
To find out more about dark versus light, visit these Web sites: www.darksky.org and www.crlaction.org.
Next month: Saving energy in Kentucky’s aluminum industry