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A petition concerning light pollution

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#1 OwlWatcher

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Posted 13 March 2018 - 05:13 PM

Idea I'm confused about :  There are a number of petition sites online. Couldn't we use one of those to send out a nationwide petition about light pollution and its negative impacts which would include energy waste. The IDA says that we throw away billions of dollars every year lighting up the bottoms of clouds. Doesn't seem to be a smart way to use our energy.

These petitions don't go on and on so a one page explanation with a photo of a bad light (arrows showing where the wasted light goes) might do the trick. Would someone help me make something up ? Not sure who would be the final recipient of the petition. The governor of each state ? The Department of Energy ? Am I just chasing the wind ?

 

Some petition sites are listed here .......... Credo, Rootstrikers, Moveon.org. Might be a few others. Thanks for your time ...... Pat

 

To: moderator ..... If the names of the sites are inappropriate in the post, please remove them. Thanks

 

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Edited by OwlWatcher, 13 March 2018 - 05:16 PM.


#2 MikeTahtib

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Posted 13 March 2018 - 05:30 PM

The problem is no longer light going up from the fixtures, but light so bright it reflects off the ground, lighting up the sky.  LED fixtures are mostly pretty good at directing their light downward, and this has been one of the selling points for these lights, but for some reason, they always use much much brighter LEDs than the bulbs they replace, promising the stargazers that they are better for light pollution because they direct their light down.  I think even the sodium vapor fixtures were pretty good about not shining directly up.  The ones that shine up are the "historical" designs, made to look like Victorian era gas lamps, but these aren't widely used.  I would recommend a poster suggesting no fixtures of more than 8 watts, and color temperature no more than 2700K.


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#3 happylimpet

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Posted 13 March 2018 - 05:36 PM

and push the health benefits, cancer risk, sleep deprivation etc



#4 caveman_astronomer

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Posted 14 March 2018 - 05:11 AM

Idea I'm confused about :  There are a number of petition sites online. Couldn't we use one of those to send out a nationwide petition about light pollution and its negative impacts which would include energy waste. The IDA says that we throw away billions of dollars every year lighting up the bottoms of clouds. Doesn't seem to be a smart way to use our energy.

These petitions don't go on and on so a one page explanation with a photo of a bad light (arrows showing where the wasted light goes) might do the trick. Would someone help me make something up ? Not sure who would be the final recipient of the petition. The governor of each state ? The Department of Energy ? Am I just chasing the wind ?

 

Some petition sites are listed here .......... Credo, Rootstrikers, Moveon.org. Might be a few others. Thanks for your time ...... Pat

 

To: moderator ..... If the names of the sites are inappropriate in the post, please remove them. Thanks

 

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The three yellow arrows at the 4 to 5 o'clock positions will be contributing to light trespass and the light will scatter too much, causing sky-glow.


Edited by caveman_astronomer, 14 March 2018 - 05:12 AM.


#5 RickHull

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Posted 14 April 2018 - 08:17 PM

Hopefully someone from the IDA managing committee is reading this.

Not to be taken wrong, but shouldn't IDA be leading these petitions?

Instead of several disjointed efforts, I would think IDA is in the best position to maximize both the information and the number of signatories.

 

Also, I would think they might be in the best position to lead and influence standards for any public fixture.



#6 earlyriser

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Posted 23 April 2018 - 02:21 PM

The problem is no longer light going up from the fixtures, but light so bright it reflects off the ground, lighting up the sky.  LED fixtures are mostly pretty good at directing their light downward, and this has been one of the selling points for these lights, but for some reason, they always use much much brighter LEDs than the bulbs they replace, promising the stargazers that they are better for light pollution because they direct their light down.  I think even the sodium vapor fixtures were pretty good about not shining directly up.  The ones that shine up are the "historical" designs, made to look like Victorian era gas lamps, but these aren't widely used.  I would recommend a poster suggesting no fixtures of more than 8 watts, and color temperature no more than 2700K.

The good news is that light reflecting up from the ground - all else being equal - contributes significantly less to sky glow than light emitted directly from the fixture.

 

This is a graph of the average emission intensity verses angle for a typical city. This model is used extensively in predicting sky-glow.

 

City Emission Function.jpg

 

From Garstang, R.H. 1986, Publ. Astron. Soc. Pacic, 98, 364-375.

 

If you look closely at the graph, you'll see that the overall emissions are a composite of ground reflections (circular emission curve sitting on the orgin) and direct low-angle emissions (the airfoil shaped curves on either side of the orgin near the ground).

 

Now, the bulk of the ground emissions are directed at the zenith, which means two things: (1) a decent percentage of these emissions will pass harmlessly through the lower atmosphere into outer space, and (2) the sky-glow near the zenith caused by scattering of this light, which typically occurs in the lower 8 km of the atmosphere, will be largely confined to areas in and close to the city.

 

Turning to the direct emissions, not only are these significantly more intense, but they must pass through a large cross-section of the lower atmosphere, which means a large portion (50% or more) of this light ends up being scattered downward and contributing to sky-glow. Not only this, but they will be traveling through and being scattered by the bottom 8 km of the atmosphere for many miles beyond the city limits.

 

Thus, it really is worth it to try and have lighting regulations that require full-cutoff lighting. It makes a difference, especially in suburban, exurban, and rural areas.


Edited by earlyriser, 23 April 2018 - 04:44 PM.

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#7 MikeTahtib

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Posted 23 April 2018 - 09:34 PM

Full cut-off is certainly important, but I wonder if most of the sodium vapor lamps did a good job of this already.  I say this because the difference in my sky from sodium vapor street lights to LED street lights has been significant.  I would love to have the sodium vapors back.



#8 earlyriser

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Posted 24 April 2018 - 03:56 AM

Full cut-off is certainly important, but I wonder if most of the sodium vapor lamps did a good job of this already.  I say this because the difference in my sky from sodium vapor street lights to LED street lights has been significant.  I would love to have the sodium vapors back.

The Department of Energy uses a typical baseline value of 2% uplight for HPS, but that may be optimistic. The problem with LED is that blue light scatters so much more efficiently than yellow light. 

 

https://www.energy.g...ct-sky-glow.pdf

 

According to the above study, if you assume that LED streetlights have 50% of the output of HPS and 0% uplight, their contribution to sky-glow in town is about a wash with HPS. My guess is that a lot of LED installations are not reducing their output as compared to the HPS lights they are replacing, which means they will increase sky glow, at least in the city. 

 

The improvements from cut-off lighting are most significant in places like parking lots, which often aim their 400 watt metal halide lights at 45 degree angles or buildings with floodlights pointing horizontally out toward the edge of their properties. Because of the scattering issue, it's critical to require full cut-off lights everywhere to minimize their impact. If we could eliminate the low angle component of the above graph, it might make up for the increases in the ground light. Especially at dark sky sites outside of town.



#9 MikeTahtib

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Posted 25 April 2018 - 09:16 AM

The Department of Energy uses a typical baseline value of 2% uplight for HPS, but that may be optimistic. The problem with LED is that blue light scatters so much more efficiently than yellow light. 

 

https://www.energy.g...ct-sky-glow.pdf

 

According to the above study, if you assume that LED streetlights have 50% of the output of HPS and 0% uplight, their contribution to sky-glow in town is about a wash with HPS. My guess is that a lot of LED installations are not reducing their output as compared to the HPS lights they are replacing, which means they will increase sky glow, at least in the city. 

 

The improvements from cut-off lighting are most significant in places like parking lots, which often aim their 400 watt metal halide lights at 45 degree angles or buildings with floodlights pointing horizontally out toward the edge of their properties. Because of the scattering issue, it's critical to require full cut-off lights everywhere to minimize their impact. If we could eliminate the low angle component of the above graph, it might make up for the increases in the ground light. Especially at dark sky sites outside of town.

Most LED installations are definitely not reducing their output, but are dramatically increasing their output, at least in my area, and many areas I've read about.  My town wen tfrom 60 watt HPS to 29 watt LED.  When you change your light bulbs to LED, it's about 1/8 toget equivalent light output.  I bought a light meter to measure our streetlights (wth scotopic filter), and the LEDs were far far brighter. 



#10 earlyriser

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Posted 25 April 2018 - 09:49 AM

Most LED installations are definitely not reducing their output, but are dramatically increasing their output, at least in my area, and many areas I've read about.  My town wen tfrom 60 watt HPS to 29 watt LED.  When you change your light bulbs to LED, it's about 1/8 toget equivalent light output.  I bought a light meter to measure our streetlights (wth scotopic filter), and the LEDs were far far brighter. 

I don't know how big your town is, but my guess is installations managed by governing organizations that lack engineering resources (e.g., local governments) will install LEDs with equal or greater light output than the HPS they are replacing, which is both a waste of power and damaging to the environment. Those managed by state and Federal Department of Transportation organizations are more likely to set and follow recommended engineering guidelines.

 

If your state DOT has engineering guidelines for streetlights (Ohio does), I'd be sure to request the town follow that if for no other reason than to avoid liability for creating an unsafe condition from excessive glare by not following them.



#11 MikeTahtib

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Posted 27 April 2018 - 09:58 AM

The brightness in my town was driven by the police chief, who believes the brighter the safer (like a prison yard).  If you have a link to some sort of standards, I'd like to see it.  Everyone I talk to says the saem thing = what are the safety standards, but I haven't seen any.  And if they actually impose maximum brightnesses, that's great.  I thnk a lot fo people assume brighter is safer, without limit.



#12 csrlice12

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Posted 27 April 2018 - 10:52 AM

All that generated power has to go somewhere and street lighting is the easiest way....better to ask why our power plants always operate pedal to the metal instead of being able to ratchet down the output when the power is not needed.



#13 earlyriser

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Posted 27 April 2018 - 11:36 AM

The brightness in my town was driven by the police chief, who believes the brighter the safer (like a prison yard).  If you have a link to some sort of standards, I'd like to see it.  Everyone I talk to says the saem thing = what are the safety standards, but I haven't seen any.  And if they actually impose maximum brightnesses, that's great.  I thnk a lot fo people assume brighter is safer, without limit.

Standards exist. Below is a link to one source. I'll see if I can find a link to some exemplary numbers from this one.  The police chief shouldn't be making decisions about street lighting any more than the Traffic Engineers should be making decisions about what kind of gun the police should carry.

 

https://www.ies.org/...ing-facilities/

 

This is a link to a table that shows some recommended light levels from the above standard:

 

https://www.lighting..._Rev.072013.pdf

 

Here is a Traffic Engineering Manual from the Ohio Dept. of Transportation:

 

http://www.dot.state..._bookmarked.pdf

 

From the ODOT Manual:

 

1106-2.2 Intensity

 

The initial average intensity for lighting ODOT-maintained freeways shall be 1.0 to 1.2 footcandles, and all lighting design should attempt to approximate the 1.2 value without exceeding it, except where this limitation results in an unacceptable uniformity ratio as specified in Section 1106-2.3. For non-freeway lighting, reference should be made to Table 1197-4 for recommended average maintained horizontal illumination levels.


Edited by earlyriser, 27 April 2018 - 11:50 AM.


#14 George N

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Posted 30 April 2018 - 01:49 PM

The brightness in my town was driven by the police chief, who believes the brighter the safer (like a prison yard).  If you have a link to some sort of standards, I'd like to see it.  Everyone I talk to says the saem thing = what are the safety standards, but I haven't seen any.  And if they actually impose maximum brightnesses, that's great.  I thnk a lot fo people assume brighter is safer, without limit.

I think the best you can hope for is to convince the "powers that be" in your town of the errors they have.

 

Here is the IDA's newly released recommendations for "Criteria for Community-Friendly Outdoor Sports Lighting": http://www.darksky.o...ports-lighting/

 

They have other recommendations that are agreed to by the lighting engineering society.

 

One point of hope: LED street and parking lot lights can very easily be changed in brightness - no new bulb required. (I believe that color change does require new bulbs.) Two friends have in fact convinced their town to reduce the brightness of new LED streetlights in front of their homes. Alas, they went down from "nuclear explosion" to merely "way too bright" - but at least there's hope. My friends hope to try again, and their neighbors have no problem with less-bright streetlights. Interestingly, their Town has a very good anti-LP law - that exempts the Town Gov't from following.




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