How Flagstaff, Arizona, Switched To LEDs Without Giving Astronomers a Headache (arstechnica.com) 88
Scott K. Johnson from Ars Technica reports on how Flagstaff, Arizona, switched to energy-efficient LEDs without giving astronomers a headache from the harsh blue-rich light they produce. An anonymous reader shares several excerpts from the report: Flagstaff became the first city to earn a designation from the International Dark Sky Association in 2001. That came as a result of its long history of hosting astronomy research at local Lowell Observatory, as well as facilities operated by the U.S. Navy. The city has an official ordinance governing the use of outdoor lighting -- public and private. A few years ago, though, a problem arose. The type of dark-sky-friendly streetlight that the city had been using was going extinct, largely as a casualty of low demand. In fact, as of this summer, there are none left to buy. Meanwhile, the age of the LED streetlight has arrived with a catch: limited night-sky-friendly LED options. The problem with LEDs boils down to blue light. Older streetlights are high-pressure sodium bulbs, which produce a warm yellow glow around a color temperature of 2,000 K. The bulbs Flagstaff relied on for most of its streetlights were low-pressure sodium -- a variant that only emits light at a single wavelength (589 nanometers) near that yellow color, producing something resembling candlelight. Many of the LED streetlights on the market have much cooler color temperatures of 3,000 or even 4,000 K.
[...] Narrow-band amber (NBA) LEDs [...] actually use a type of LED that only emits warmer colors from the start. In this way, they actually compare pretty well to the low-pressure sodium streetlights that recently went extinct. The range of wavelengths emitted is a little broader, but the practical effect is about the same. Separately from all this wavelength wrangling, though, LEDs do have a strong natural advantage -- they're highly directional. That is, LED streetlights do a much better job of only lighting the street (rather than the adjacent homes). That means that fewer lumens coming out of the fixture can give the same result you had before. Flagstaff's plan is generally to swap in NBA LEDs for all the low-pressure sodium lights, and PCA LEDs [lights known as phosphor-converted amber (PCA) shift all the light out of the blue and into the yellow part of the spectrum at the cost of some efficiency] for the high-pressure sodium lights that are used along the busier streets (as they're a little brighter). The better directionality of LEDs -- combined with resident requests for slightly dimmer lighting on residential streets -- actually means that the total output of the city's streetlights is going to drop from about 29 million lumens to about 19 million lumens. That's not unusual. In closing, Johnson says Flagstaff's hope is to produce the first dark-sky ordinance updated to deal with LEDs that could give other cities an example to follow.
[...] Narrow-band amber (NBA) LEDs [...] actually use a type of LED that only emits warmer colors from the start. In this way, they actually compare pretty well to the low-pressure sodium streetlights that recently went extinct. The range of wavelengths emitted is a little broader, but the practical effect is about the same. Separately from all this wavelength wrangling, though, LEDs do have a strong natural advantage -- they're highly directional. That is, LED streetlights do a much better job of only lighting the street (rather than the adjacent homes). That means that fewer lumens coming out of the fixture can give the same result you had before. Flagstaff's plan is generally to swap in NBA LEDs for all the low-pressure sodium lights, and PCA LEDs [lights known as phosphor-converted amber (PCA) shift all the light out of the blue and into the yellow part of the spectrum at the cost of some efficiency] for the high-pressure sodium lights that are used along the busier streets (as they're a little brighter). The better directionality of LEDs -- combined with resident requests for slightly dimmer lighting on residential streets -- actually means that the total output of the city's streetlights is going to drop from about 29 million lumens to about 19 million lumens. That's not unusual. In closing, Johnson says Flagstaff's hope is to produce the first dark-sky ordinance updated to deal with LEDs that could give other cities an example to follow.
Who needs streetlights? (Score:5, Funny)
I wear an LED headlamp.
Re:Who needs streetlights? (Score:5, Informative)
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I know people feel safer with street lights, but is there any real evidence that people are actually safer with them?
For me, the only useful part of a street light, is when you are out of the city area. there is a single light to show that there is a road intersection, without a traffic light.
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My astronomy professors always made a correlation!=causation joke by highlighting the direct relationship between lights and crime. NYC? Lots of lights, lots of crimes. South Dakota? Not a lot of lights, not a lot of crime. Therefore, more streetlights means more crime.
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I don't know about real evidence. I do know I engaged in all kinds of crap as pre-teen/teen and lights definitely had an impact on where I roamed. Kids are mostly screwing around and vandalizing but I don't see that the situation changes much if someone had a more serious agenda. Darkness provides cover and cover provides opportunity. It so strongly follows that I'd be skeptical of the bias and agenda behind any evidence trying to show otherwise.
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I know people feel safer with street lights, but is there any real evidence that people are actually safer with them?
I read a study decades ago about that subject. There was a remarkable decrease in crime where street lights did lead to a decrease in crime in the area. It would be interesting to see a more modern study done. My thinking is all a street light would do is give your mugger better light to rob your ass.
I never really understood our obsession to light up every fucking alley and hole 24/7. Are we that afraid of the dark? It just makes no sense, other than the example cited above.
To me it makes sense t
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"My thinking is all a street light would do is give your mugger better light to rob your ass."
I mean there are places so horribly bad you can get away with visibly robbing someone in the street and there are places you wouldn't get through a whole mugging without a patroller shining a light on you. But most places fall somewhere between where you aren't likely to get mugged, someone definitely couldn't rob you in the light without someone else seeing and calling a cop, but someone could take advantage of da
Loathe the LEDs I have in my neighborhood (Score:2, Informative)
Around mid-summer last year, FPL switched out all the street lights for those God-awful "daylight" LEDs. Now the neighborhood looks like a post-apocalyptic sci-fi movie set at night. The lights also glare on your windshield horribly while driving, since the beam is more confined than the old HPS bulbs.
I'm glad somewhere else is at least not making the same mistakes. Now, if only FPL would replace the garbage they installed here...
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I'm glad somewhere else is at least not making the same mistakes. Now, if only FPL would replace the garbage they installed here...
I'm curious and have several questions.
Are you willing to see your own taxes go up in order to pay to replace these bulbs?
Are you willing to see all your neighbors taxes go up also, regardless of their financial situation, in order to replace these bulbs?
You should have been making a stink BEFORE they were purchased and installed. Seems to me that making the stink now is a big "fuck you" to your poorest neighbors.
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You should have been making a stink BEFORE they were purchased and installed. Seems to me that making the stink now is a big "fuck you" to your poorest neighbors.
That would've been great if they had reached out to the community for feedback, but that didn't happen. As near as I can tell, there isn't a whole lot of stink being raised over it, either. I'd guess most people just figure since the new light bulbs are saving the environment, only people who hate the planet would dare criticize them (most people probably aren't aware street light LEDs are available a less obnoxious color temperature).
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Slashdot seriously needs to add an edit feature...
Also, there's no reason for FPL to charge anyone for the cost of replacing these abominations. They are still in the process of retrofitting street lights and could easily re-install the bulbs in a commercial zoned area, where they'd fit right in with the metal-halide lamps on buildings. Yeah, there's labor costs, but like the old joke goes, how many guys does it take to screw in a light bulb?
None. Guys don't fit inside a light bulb.
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Haven't been able to find a place for discussing Slashdot meta, do you know of any?
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The LEDs will last 10-15 years (on average), the MTBF is mean time "between" failure and is a function of all the products in use. So if you have a set of 1000 LED with 50,000 hours MTBF, you will have a mean of 50 hours between 2 failures.
The problem with LED lights is typically a combination of poor build quality and overdriving. In many cases replacing a coil or capacitor with a better, higher voltage one will fix an LED panel. I've seen 50V capacitors used on a line voltage LED bulb to save costs and sp
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What is so bad about Red LEDs? Especially for night. Just don't use the Blue LED. I know some people got the Noble Prize for the discovery of the Blue LED, we don't need to use it for all lighting needs. Night street lights, would probably be much better if it was Red, or Orange (By mixing some green LED in the mix). It would be easier on our eyes. Cause less glare and other problems.
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Night vision red sensitivity is very, very poor. Although red LEDs can have astonishing 70% power efficiency http://donklipstein.com/led.html [donklipstein.com], the closer you get to green, the higher lumens/watt is. Red: 42 lumens/watt, green 237 lumens/watt. If you find green unpleasant, amber is a good compromise at 161 lumens/watt.
Back in the days of black-and-white photographic print making, safelights were amber. Red would have been inconveniently dim compared to amber.
No Dark Skies (Score:5, Insightful)
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North Korea is great for keen astronomers!
https://pbs.twimg.com/media/Dd... [twimg.com]
(I feel your pain)
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Actually a significant portion of the non-western world is ... and so is Australia https://www.lightpollutionmap.... [lightpollutionmap.info] :-)
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As a landlord there are state and federal rules on who can and cannot choose to be a tenant. Which usually isn't a big deal if you are not some sort monster. However because you are the landlord. You are responsible to your neighbors needs, so while you can choose your neighbors, they neighbors will complain and have issues that you need to address. Which may not necessarily be the ideal neighbor.
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Re:No Dark Skies (Score:4, Informative)
Check if your neighborhood has "light trespass" laws. If not, then start advocating for them!
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My neighbour had the same thing. Over a beer I discussed if it were possible to position the sensor so it isn't triggered by anything in my garden. I then showed him the photos I take with my telescope and the day after the light was not only not being triggered but he put up a small board that prevents the light from shining in my yard at all.
Some people out there are still reasonable.
As to your dark skies, I feel you. https://www.lightpollutionmap.... [lightpollutionmap.info] Don't be fooled by the non standard TLD that's a legit
Hotter, not cooler (Score:2)
Older streetlights are high-pressure sodium bulbs, which produce a warm yellow glow around a colour temperature of 2,000 K. .... Many of the LED streetlights on the market have much cooler colour temperatures of 3,000 or even 4,000 K.
If you are going to name your colours using the temperature of the blackbody that produces them you need to realize that 4,000K is a lot hotter than 2,000K. If something is white-hot it's at a lot higher temperature than something red-hot.
Re:Hotter, not cooler (Score:4)
Most every light bulb package on the store shelves has both the color temperature specified in Kelvins, and a color description on the "warm", "cool", "daylight" scale. If you had ever looked at any, you'd know that "cool" bulb colors do indeed refer to hotter color temperatures. That's just the way it is, no matter how stupid it sounds.
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I think the 'color temperature' was invented by arts majors, not physicists.
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Exactly. On lightbulb packaging, the "warm, cool, daylight" text will be the opposite of the temperature in Kelvins.
But since art people say "blue = cold" and "red = hot", we have the dumb system we currently exist in.
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Yeah, but do you actually realize you felt for a trick question?
Hint: Flame is not the same as molten steel.
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Most people _are_ aware of it.
They simply are bad at reading/comprehension.
Oh: he meant flame!!! Not simply the colour of a hot thing.
It is a trick question.
TP is full with them.
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And based on the number of students I used to teach who would get it wrong before my class, I'm pretty sure it's a more general problem.
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The trick is that "white" is in the set of answers and everyone knows that the hottest things are white.
So they tricked into answering white instead of thinking about the flame (which btw. has no white part).
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Most people _are_ aware of it.
They simply are bad at reading/comprehension.
Oh: he meant flame!!! Not simply the colour of a hot thing. A flame usually has no white part, so indicating it as a possible answer you trick the brain thinking about hot things that can be white.
It is a trick question.
TP is full with them.
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I think the 'color temperature' was invented by arts majors, not physicists.
It's an important measure in photography. Editing software has specific controls for changing the average color temperature of an image.
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I think the 'color temperature' was invented by arts majors, not physicists.
Even the slightest bit of research would reveal the Kelvin temperature of stars roughly aligns with the color temperature scale. Noonday color temperature of our sun is roughly 5500 Kelvin.
In short, Google is your friend in case you hadn't known this already from astronomy class.
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And if you had looked at lightbulb advertising, you would see that "warm white" is ~ 3000K and "cool white" is ~ 4000k.
The "daylight" bulbs don't specify warm/cool, but are around 5500K. Though I bet if you looked at their spectrum it would not be even close to actual daylight. This is probably why "cool white" is lower than "daylight" for some reason, you would think it would be more bluish.
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You're right, most daylight bulbs are nothing close to daylight. I grow aquatic plants in my fish tank (well, mostly algae, but I TRY to grow aquatic plants). This is something that has plagued aquatic gardeners for decades.
A bulb might be labeled daylight because the overall color temperature does indeed seem balanced like sunlight, but if you look at the spectrum you might see that it only has two or three spikes in certain spectrums, which average out to a daylight color. Because different plants pref
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like starbucks calls their smallest cup "tall"
Actually, it's not their smallest size. There is also a "short" size, which is even smaller than "tall" [starbucks.com]. Not sure it's available in all Starbucks though...
Re:Hotter, not cooler (Score:4, Insightful)
Describing colours as "warm" and "cool" isn't marketing speak. They're historical terms, related to our own psychology, and used since before we knew what light was or how it was produced.
Hot things, like the sun, candles, fire and stoves, are red and orange. Cold things, like water and ice, are white or blue.
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Color warmth is built more around natural occurrences of the color.
Cool colors:
Blue: Ice, Sky, Water
Green: Grass and Plants
Warm Colors:
Yellow: The sun, Summer flowers
Red: Fire, Lava
The cool colors are often from reflected items, while the Warm Colors are from emitted items. Scientifically it is bad classification. But if you are going to paint something in real life, it makes more sense.
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Missed the point while counting beans. (Score:3)
The temperature referred to, is the amount of infrared, aha heat radiation that you feel from objects glowing with that color.
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Bringing up tristimulus is irrelevant. Cyberax was basicly refuting Waffle Iron claim that the "cooler" light is actually hotter.
The temp in k is the temperature of an ideal black-body radiator that radiates light of a color comparable to that of the light source. You can create the 4000k light without heating iron to 4000k
Going with the assumption that ess efficiency = more heat. And if we talk about lighting efficiency that has more to do with technology and what our eyes perceive than wavelength. IIRC
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Yes that's why the blue tap in my house has hot water, because blue is hot and red is cold, and everyone in the world is a physicist who thinks in kelvin.
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Try this when flying at night (Score:5, Interesting)
I was worried about the earlier LED streetlamps, but newer ones are really great.
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Yeah, having hoods to direct the light down is even more important than the color/temperature. What is the point of aiming the light upwards where it will only cause glare and light pollution?
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We are still going to be using RADAR for a very long time.
Are you sure? ADS-B
NEXRAD.
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Aliens see with IR, haven't you seen Predator?
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You can actually see old sodium streetlamps and bad LED lamps. You can't see newer streetlamps, you just see the cone of light that they cast. There's almost no light leaking uselessly into the sky.
By definition, if you can see the cone of light that they cast, there's light leaking uselessly into the sky. It's reflecting off the ground. That's how you're seeing it.
Of course, you can't really solve that problem, at least not reasonably. Presumably it's physically but not economically possible to build surfaces and lighting systems which would only reflect at lower angles.
Please set an example for my neighborhood (Score:2)
I wish we had amber LEDs instead of high temperature lowest bidder bullshit they replaced all the HPS here /w.
So annoying driving at night I hate it. They don't even have diffusers... Looking up is like gazing into a little sun.
3k a cooler temperature than 2k? (Score:1)
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Not seeing it (Score:1)
"hat is, LED streetlights do a much better job of only lighting the street (rather than the adjacent homes)."
How is that an advantage? I'm sure there was an annoying spot here and there but for the most part some level of lighting for streetside yards and sidewalks is a desirable effect and reduces crime. This just shifts more cost to homeowners and the poor or absentee homeowners won't do it leaving neighborhoods much darker and more dangerous at night.
Believe me, I was a teenager once. The darker street i
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How is that an advantage?
Streetlights not shining in my window is an advantage. I have a very hard time sleeping when it's light.
I'm sure there was an annoying spot here and there but for the most part some level of lighting for streetside yards and sidewalks is a desirable effect and reduces crime. This just shifts more cost to homeowners
The homeowners pay the taxes that keep the streetlights on. It only shifts the category the cost is in.
and the poor or absentee homeowners won't do it leaving neighborhoods much darker and more dangerous at night.
Absentee homeowners are solved with a tax on unoccupied dwellings. If that doesn't induce them to rent or sell, at least you can spend the money on police patrols. Unoccupied dwellings have a real cost related to crime, because people target them for theft of fixtures and such.
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We still have unoccupied dwellings? I thought AirB&B had pretty much solved that. (Not sure if I'm joking or not based on the news stories from Colorado and other places with high tourist influx.)
I can't speak to every place, but my hometown of Santa Cruz definitely has both. There's multi-million dollar vacation homes which are occupied maybe two or three weeks a year, where the owners don't need the airbnb money and would rather not risk someone trashing their places. The places they're located get patrolled more heavily than other neighborhoods, of course, with the result that people who only pay property taxes and little other money into the local economy consume more than their fair share of po
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Renters are still absentee owners because the tenents wouldn't buy lights.
"The homeowners pay the taxes that keep the streetlights on. It only shifts the category the cost is in."
To one that makes the cost divided by number of owners (each paying full cost) rather than the cost/benefit they get from the service (property value). Instead of a fair pooled cost for efficient centralized lighting with group purchase you have individual home owners shelling out full retail on a one off basis and absorbing costs
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Renters are still absentee owners because the tenents wouldn't buy lights.
California requires all kinds of stuff from landlords, this could reasonably be added to the list.
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Yeah because the lady who inherited a rental property from her parents and gets a check periodically as passive income from a management company is going to know it is needed, that law even changed, or going to default on the side of better lighting rather than minimal compliance. Of course not, that owner is going to minimize expense to maximize their return on investment.
There is a reason home owners don't generally want renters coming in or city councils to expand rental in their area. Neither the renter
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There is a reason home owners don't generally want renters coming in or city councils to expand rental in their area. Neither the renter nor the homeowner have the same kind of interest in the property and property values.
Unfortunately, people who live in that particular area generally can't afford to buy homes. Most of the high-paying jobs are at best over the hill in the silly valley, and the commute over there is murder now. There used to be a rail line over that route, but some of it has become highway now and most of the tunnels have collapsed at least partially.
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That shouldn't be the case since renting is more expensive then owning but somehow *cough banks cough* it always works out that way.
If renting is the norm in flagstaff, especially with a higher propensity toward renters who care less about the properties, poorer lighting is probably a bad idea. That is only going to lead to a decline. It might just mean lower property taxes with the wealthier areas coming out ahead because their co-ops have already bought the lighting for their gated communities and more lo
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That is, LED streetlights do a much better job of only lighting the street (rather than the adjacent homes).
How is that an advantage? I'm sure there was an annoying spot here and there but for the most part some level of lighting for streetside yards and sidewalks is a desirable effect and reduces crime. This just shifts more cost to homeowners and the poor or absentee homeowners won't do it leaving neighborhoods much darker and more dangerous at night.
Believe me, I was a teenager once. The darker street is in far more peril from mischief I doubt that changes when the mayhem takes a more serious tone.
If lighting reduces crime, then I suppose that means we should keep lights on most of our lawyers and politicians 24/7. Perhaps if they can't sleep they won't be able to find so many creative opportunities to screw the public.
Social commentary aside, this seems like a problem simply solved by motion sensitive lights. Governments can require landlords to install them in areas with crime problems.
There is no need for have lights on all the time - and good reasons not to. Many people sleep better without st
Color Temps, Sleep, Safety (Score:3)
I'm part of a discussion right now where we're looking more toward replacing lights in the area with LED fixtures. We're looking at 2200K, 2700K, 3000K, and 4000K. The police want 3000K or 4000K because those provide great light for identifying suspects and moving evidence (vehicles). But those are really, really white lights.
Those more concerned about circadian rhythms want 2200K-- so your eyes aren't burned into keeping you awake. But that's some really yellow light and definitely messes with peoples' perception of color.
I'm guessing we're going to go with 2700K as the compromise.
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Oddly enough, I brought up the less-humorous idea of installing some sort of temp changer like my Ryobi spotlight has (https://www.ryobitools.com/power-tools/products/details/18v-one-plus-hybrid-led-color-range-work-light). I even brought that in to help people understand the difference in the 2700K-5000K part of the spectrum. Unfortunately, it looks like the easily changed streetlamp lights aren't yet ready to offer this kind of feature (at least at a reasonable price).
Any bulb can become night-friendly (Score:2)