| The IDA estimate for the cost of light pollution in 1998
is 1 BILLION $
For comparison, the FY2000 NASA budget estimate is 13.7 billion $. 1 billion is NOT the cost of public illumination, as one may think. This is only the cost of the WASTED light. The one that went up to produce what you see in the picture on the right. So if you're still wondering what is light pollution, here's your answer on the right. This is light pollution, a hole in your pocket. |
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Elgin is a small
Chicago Il. suburb. According to the 1990 US census, 77,010 people lived
in Elgin in 1990, a 10% increase over 1980. Judging from the simpleness
of this year's (2000) census forms, I doubt that we'll have a more accurate figure
for the next ten years. However, The city itself estimates 85,086 people
in 1996.
Anyway, the city has a public works program very nicely named: Lighting
Up the town. After correctly explaining the benefits of
outdoor lighting, the department of public works in the local government
invites you to request a streetlight. Quoting from the program web page:
"The City is eager to take residents requests for additional street lighting."
According to the same page, in March 1999, there were approx. 2150 street
lamps in Elgin and the city was paying approx. . $13/month for each of
them, that's 156$ per year.
Assuming that the city uses regular cobra-head design lamps, the
loss would be "only" 30% = 100,620$ /year. Lost, in vane, for nothing,
to illuminate the birds and airplanes. To wash the stars out of the sky...
Paid by for the citizens of Elgin, Il. But nobody's telling them. The only information I
could find is that the city uses 250 Watt lights at mid block and 400 Watt
at intersections. And that it costs 4000$ to install a new pole.
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| Lack of actual information stops me to asses the
loss in some other city. I would be interested to find the actual number
of street lamps in Baltimore, because I know that 90% of them are regular
cobra-heads. But who knows. If there were 50,000 lamps, and that's not so hard
to believe, the waste would be 2,325,558 $ per year, assuming the same
cost per lamp as in Elgin, Il. Enough to hire 46 police personnel at 50.000/year
level...
In order to asses the possible loss and to see if anything at all can be done to save this money, we need to know something else. |
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Streetlight Spectra © IDA |
I want to install a light
You're a citizen and you want to install a new street light in front of your house. The city will pay the 4000$ to install it, probably including the cost of the pole, connection, fixture and everything. Let's ignore the fixture type by now. What are the choices of lamps?
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| CHOOSING A LIGHT SOURCE
LPS lamps are the great choice of
course. The only problem is that the light is pure yellow and the color
rendition is poor. However, for applications where color rendition is NOT
essential, like regular street lighting, LPS is the only smart choice.
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SOLUTIONS, SOLUTIONS to save your money!
Solution #1 to save money:
Converting the HPS lamps to lower wattage, longer life LPS lamps that give
the SAME level of illumination (same lumens), would cut the city electricity
bills almost in half (see the cost estimate above). Thus the utility companies
electricity profits from municipalities by the same amount. They might
never let this happen unless the cities become aware of the money they
lose. Some cities did become aware as we will see below. |
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Solition #2 and The essential Step. Full cutoff fixture for every outdoor light. |
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| Choosing the right light source in not everything. You
will get the same illumination level with less money because the lamp is
more efficient, but you will still waste light.
The solution? The solution is of course to SHIELD THE LAMPS. This can be done even before replacing the light source. Virtually every light can be properly shielded and a perfect guide for this is IDA's and NELPAG's Good Neighbor Outdoor Lighting online brochure, a guide to better lighting. But a image is worth a thousand words so let's see what I mean by proper shielding: |
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Examples of properly shielded lampsWhile walking around my school in Baltimore, I've noticed that some cobra-head fixture had a full cutoff shield installed. To no surprise to me, the shielded lamps were in front of large apartment buildings, attesting that the owners had good reasons to request shielding, this is the sleep comfort of their tenants. For those of you familiar with Johns Hopkins University Homewood Campus' neighborhoods, the shielded lamps are on road that runs between Broadview and Hopkins House Apartments.The shield is a conical "skirt" of aluminum around the refractive lens of the fixture. The shield redirects the upward and side going light to the ground, increasing the illumination level down there. |
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GOOD, Shielded Cobra-Head Street Lamps near apartment buildings
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BAD, UNSHIELDED Cobra-Head Street Lamp in front of my house
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More ExamplesYou may wonder how things work on larger scales. The following two photos are courtesy International Dark Sky Association and they show the exceptional good effect converting the outdoor lighting from HPhg unshielded lamps to LPS lamps had on the illumination level. |
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University of Arizona Campus before
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University of Arizona after
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| $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$ |
| Solutions do work. They will save your money and minimize the spill. They will increase your nighttime comfort and security level, because now you have BETTER illumination at a lower cost. You amy wonder how much can you save. NELPAG, New England Light Pollution Advisory Group has prepared a little graph showing how much one could save by converting from inefficient to efficient lighting. But keep in mind, you've done only half of the job if you're shielding the lamp too. Unfortunately, I don't have a calculation for actual street lights, as NELPAG has done the calculations for typical yard security lights. | 
The money one can save © NELPAG |
| I hope now one sees the financial benefits one gets by
converting to good lighting. The money saved can be substantial. For a
whole city, it can amount to millions/year.
For the regular person, the most striking effect Light Pollution has is on his/her pocket. However, not being able to see the stars can be disastrous for the most spectacular and visual branch of science, Astronomy. That is the reason why astronomers were the first to highlight the issue. We all lose money, and we all lose the sky. Only that the astronomers noticed it first. NEXT: WHY DO ASTRONOMERS CARE. OR SHOULD CARE.
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© Alin Tolea 2000