Promoting Efficient Outdoor Lighting
(and saving the night sky!)
This is a recent (1992) NOAA composite satellite
photo of the US at night:
Can you find your city or town? What's wrong with this picture? Why do
spend money and expend energy to generate light so that we may see at
only to beam a large fraction of it into space? From satellite
images such as this one, it is estimated that 30% of all outdoor
generated in the US is
toward the sky - completely wasted. The Globe at Night
webpage makes the entire case (problems, solutions); I provide similar
Back down on the Earth....
- On a typical city
street or free-way, one can see the direct light from street lamps
to 1 or more miles away. NONE of that distant light
to our ability to see at night, whether we're walking or driving.
this light appears as glare1.
Glare constricts the pupils of our eyes and inhibits the
in the retina that allows us to see in darkness. If this light were
shielded and thus directed downward to the ground, instead of
and upward as glare and waste, the ground would be
our eyes better dark adapted, and we would actually see better at
The same could also be said of most parking lot and campus lighting.
- In a typical American urban or suburban home, street lights,
lights, and sometimes commercial lights stream into our
windows at night. There are not many who find this desirable. It is
completely unnecessary. Properly shielded home security lamps can
sufficient illumination of doorways and ground spaces near the home,
not shining in your neighbor's (or your own!) window. This is also true
residential street lighting - when properly beamed to the
the street will be lit sufficiently, with little light wasted on
up our bedrooms and homes.
Glare defeats both safety
- Vying for our attention, many businesses are
over lit, some using 3-10 times the recognized lighting industry
for site lighting (IESNA2). This excess lighting appears
as glare, causing eye fatigue and diminishing the human eyes' ability
see in darkness. Safety is compromised. Unshielded, glaring
often shines into homes. It is also difficult to see someone standing
a bright, outwardly directed, light. That same light directed downward
the door and its immediate
surroundings would provide
far better security.
light is costly: in most of the above instances, a properly shielded
bulb emitting fewer lumens would do the same job as a brighter but
shielded bulb. The long-term savings in money and
demands are obvious.
wonders of nature's night sky to wasteful, inefficient outdoor
Fewer and fewer people experience a starlit night sky
it is flooded with wasted
This sad story has been quantified and documented in this paper.
often have humans been inspired by the multitudes of stars in our Milky
What's up there? Where did it all come from? Where did we come from?
we alone?... Should we take from our children this gift of nature?
Efficient outdoor lighting is a win/win proposition for everyone.
is also available,
and becoming more so with increasing numbers
(e.g., Hubbell Lighting, Green Earth
Lighting, and Rabb Lighting).
Many communities are adopting
lighting - the cities of Los Angeles and Melbourne, Australia
replaced all of their street lights with full cut-off lighting. Here are
to state (e.g., Connecticut)
& local outdoor lighting laws/ordinances. Here's an
Lighting Code Handbook. With the increasing costs associated with
power (e.g., building new power plants, generation of green house
power companies are beginning to see the advantanges of efficient
lighting. Everyone wins.
Here are some (1,
2, 3) short
to the problem of light pollution and its solutions.
Additional information may be found at the web pages
of the International
Association , its Michigan Chapter, and
Light Pollution Advisory Group.
1If this term is unfamiliar to you,
about where you point a flashlight when walking in the dark - at
away from your eyes. A flashlight pointed in the direction of your
produces glare, disabling you from seeing your surroundings.
Engineering Society of North America
Professor of Astronomy
Department of Physics
Western Michigan University
Last edited: 17 March, 2009