High-quality exterior lighting benefits modern society.
However, the byproduct of poor lighting installations, light pollution,
is commonly seen as glare, spillover, and sky glow. The objective is not
necessarily to have less light on the targeted object, but to have better
light. Manufacturers of sky-friendly fixtures, below,
offer viable alternatives to typical, offensive outdoor lights. You have
What's the problem?
Why should I care?
What can I do?
is light striking your eye directly from the source. A veil of light
across your field of view reduces the contrast between objects--you can't
see as well in the stark brightness.
motorist and pedestrian safety, drivers need to discern objects at
night. The two
critical road signs at this intersection (left)
are difficult to see because the eyes are overwhelmed by direct light,
creating a hazard. Glare hinders
true security by creating extreme shadows, offering refuge to criminals in
spite of the bright lights. Glare can be discomforting, disabling, or
blinding. As we age, the effect--and its impact on our lives at
adjustable lights downward so they are level with the horizon. Purchase
dark-sky friendly fixtures that have the light bulb tucked into the
luminaire housing, not exposed to the eye. Install only light
fixtures that are fully shielded. Install
security lights with motion detectors for greater security. With
lighted signs, request lighter text and logos/graphics against a dark,
is light that extends beyond the targeted object. This includes
light trespass, which extends beyond property lines.
that is broadcast well beyond the intended area is wasted--an unnecessary
loss of money. Light that encroaches upon the property of others,
such as into bedroom windows, is
a personal infringement. Neighbors are entitled not to have your bright
lights shining into their personal space. Roadway light that spills
into adjacent properties represents a waste of tax dollars.
floodlights with clip-on visors and aim the fixtures downward. Install fully
shielded lights, and do not place
light mounts where the light crosses
property lines. Save money by lessening the light
output (in lumens) of existing fixtures.
glow is the garish hue seen overhead from artificial light
scattering in the atmosphere. The reflected light masks the
background stars and creates a pallid-looking sky.
could readily save the tax dollars spent on
lighting the clouds. Light sent skyward is a waste of that light
(<2% of the cost) plus the additional energy loss (~98% of the cost)
that went into producing the light pollution. (See Energy
Chain.) Our children are
losing the heritage of the night sky. Most
of them are unable to see the Milky Way galaxy or other dark sky
wonders. Nocturnal animals are disrupted by the abnormal night
lighting. Some studies suggest human health is negatively affected
because of disrupted circadian rhythms due to light pollution.
||Install simple visors over existing lights
and purchase fully shielded fixtures. Find a less offensive way
to express yourself than through outdoor vanity lights (right) and
landscape lighting. Ask your elected officials to
select public lighting fixtures that don't waste your tax dollars
skyward. Help reclaim the vast public space overhead. Aim
billboard lights down instead of up.
Crelin offers clear diagrams that convey the qualities of dark sky-friendly
||In broad terms...
"For a typical unshielded light fixture, 50% of the light shines
upward. This is a direct waste and is the main cause of light pollution.
About 40% of the light shines downward...Light emitted horizontally tends to create glare, working
against the productive light. A shielded fixture eliminates the upward
light and minimizes glare, allowing a much smaller wattage bulb to be
used." Courtesy of the U.S. National Park Service.
Caveat: The total energy loss is much worse than it
appears. See Energy Chain.
of Sky-Friendly Lights
Do it right.
A thorough list of good lighting fixtures and manufacturers are suggested
by the International
Dark-Sky Association. Good alternatives are readily available in all
categories, styles, and price ranges.
Shield your floodlights and spotlights with a simple clip-on visor.
Starry Night Lights is a night-friendly outdoor lights store.
Outdoor Lighting Associates specializes in retrofits.
Soft Lighting Systems claims its sports facility lights permit no direct light
above the horizon.
Dark sky friendly light for illuminating flags on flagpoles.
See also http://www.youtube.com/watch?v=ln25agg6RsQ
for YouTube clip.
Lunar-Resonant Streetlights adjust brightness output to respond to ambient
What Else Can I Do (that saves me money)?
||Right now you can save money and improve the night sky--without it costing you a
thing. For example, if your outdoor lighting fixture has
unscrew one or more bulbs (as shown) to lessen the output. You
probably won't miss the extra light. Many neighborhood lights often do more to inhibit visibility (via
glare) than they contribute to real safety. The glare of direct light
creates strong shadows and poor contrast, rather than illuminating the
- Install a motion detector on exterior security lights. You save
money while having a more effective deterrent.
- Replace wide floodlights with narrower spotlights of equal or less
- Aim all floodlights or spotlights downward so they are at least 45 degrees below the
- When replacing incandescent light bulbs with energy-efficient bulbs, use a
lower wattage, for the light output (in lumens) of the energy-efficient bulbs
is likely greater than that of the old bulb it is replacing. Otherwise you
are only swapping one high-wattage light bulb with an equally high-wattage
- Install dimmer switches and timers.
For the do-it-yourselfer, don't be swayed by the misleading
illustrations in the Home Depot Buyer's Guide. Every lighting
application around the home is available in a night-friendly version. The Buyer's
Guide ignores the impact of exterior lights and erroneously suggest their
outdoor light is confined to well-defined limits.
Other NightWise resources