Updated 9/12/08
Saving the
Night
Theft is occurring nightly before our very eyes.
Increasingly, our dark nocturnal canopy is falling victim to the predatory
glare of excessive and misdirected lighting, known by the popular term "light
pollution." This rape of the sky's quiet majesty is not just a problem of
aesthetics, however; wasted light costs us money, contributes to air pollution,
compromises safety and security, intrudes onto our property, and invades our
privacy. And although the solution is really quite simple, it will take a
concerted and cooperative effort by all of us to address the situation
properly.
The culprit in this luminous larceny is misdirected
light, illumination gone astray. Light intentionally directed upward, often
seen lighting billboards and public buildings, is the worst offender since much
of it simply splashes beyond its intended target. Other instances of
misdirected lighting result from poorly shielded fixtures that still allow
light to escape upward and horizontally. Such illumination not only destroys
the beauty of the starry night but actually hinders the eye's ability to see by
creating both glare and deep, dark shadows. In fact, poorly designed lighting
installation along thoroughfares may affect a driver's vision in much the same
way as do oncoming highbeam headlights.
There are other important concerns as well. It has
been estimated that 30% of the electricity generated for outdoor illumination is
wasted. According to the International Dark-Sky Association (IDA) that comes to over $10 billion annually. In the case of taxpayer-funded public lighting, the issue also becomes one of fiscal
accountability. Important, too, are the environmental costs of producing the
energy to power wasted light. For example, for every kilowatt hour of
electricity used based on the normal mix of energy sources, inlcuding coal, almost two pounds of
carbon dioxide and almost two grams of sulphur dioxide (responsible for acid rain) are emitted
into the environment. Thus, by simply eliminating wasted light, those amounts can be substantially
reduced with no adverse effect on necessary lighting and with decidedly
positive environmental benefits.
For individuals and families another significant
issue is that of light trespass, the spilling of unwanted light onto private
property. This concern is already addressed in some local zoning codes where
maximum light levels at property lines are established; but as the problem
becomes more common, homeowners may also sense that the intrusion of unwanted
light keeps them from using their outside property at night as they wish or may
even interfere with indoor activities by shining into the house interior.
Indeed, legal proceedings could result from such unwanted intrusion as a
violation of property rights. Furthermore, poor quality lighting, whether
commercial, municipal, or residential, can lessen the appeal of a neighborhood,
lowering property values if the area begins to look too bright and gaudy.
Yet the problem of light pollution is easily
remedied. In general, good lighting uses only the amount of light necessary for
a specific purpose, and that light is directed properly. Lights allowing no
illumination above the horizontal plane of the fixture and mounted at the
proper height to do their job while avoiding glare and light trespass are the
ideal. Inexpensive shields to retrofit older lights accomplish the same thing.
In recent years, too, there has been a conscious effort by many municipalities,
businesses, and individuals to better address the ways lighting is used and to
promote the installation of sensible lighting whenever possible.
So the next time you are out at night, make a note
of the way things are lit and why. Which fixtures are examples of good
lighting? Which could be improved by shielding? Which are unnecessary? Remember,
regardless of how we achieve the goal of reducing light pollution, the simple
fact remains that we all win when sensible lighting is used. Good lighting
saves energy and money, it reduces pollution, it improves the appearance of
neighborhoods and maintains property values, it enhances the scientific and
aesthetic appreciation of the glories of the night sky, and it preserves that
beauty and inspiration for us and for our children. So when you find yourself
lucky enough to be in a place where it is still dark enough to see the sky
shimmering with stars, think how much less beauty there would be in the world
without it. And become an advocate for sensible and efficient lighting.
Some useful sites for information on light pollution and
its solution: