Energy saving street lamps?

[james_s]

I think if they ramped up to full brightness over a period of say half a second it would be fast enough yet still not so fast that it felt jarring. I know from experimenting with dimmable consumer LED bulbs that running at 10% of full rated power consumption results in considerably more than 10% apparent light output. Partly due to non-linearity of the eye, but LED efficiency also rises pretty dramatically as current drops.

[f4eru]

What about fade the lights over a period of several seconds when brightening and a minute or two when dimming?

Brightening a light gradually is what signals animals, including human mammiferes that the sun is rising.
It will mess up the sleep.

[james_s]

Brightening a light gradually is what signals animals, including human mammiferes that the sun is rising.
It will mess up the sleep.

But brightening up over a period of a second or two? I hardly think that will trigger it. Certainly for me I find it much less jarring to ramp up the bedside lamp slowly if I need to turn it on for some reason than to just flip on a light without a dimmer. We're not talking ramping up the light over a half hour period or something.

[SiliconWizard]

Saves energy but ends up costing more due to costs upgrading the light fixture 
Then the next generation will have solar panels on top. Toss them, and repeat.
Then the next generation will have superior LEDS. Toss them, and repeat...

Absolutely! Where I live they even have changed fixtures twice since they switched to LED-based lights! Besides, those lights sold for public markets are extremely expensive. Total rip-off.

Additionally, whereas they draw much less power, they have much more brightness, partly due to their specific spectrum but probably partly for marketing reasons. Some streets at night are so bright that it's almost like dim sunlight... crazy. This night light pollution is a real problem and has increased significantly with LED-based lighting.

https://news.nationalgeographic.com/2017/11/light-pollution-energy-LED-bulbs-spd/

[stj]

Additionally, whereas they draw much less power, they have much more brightness, partly due to their specific spectrum but probably partly for marketing reasons. Some streets at night are so bright that it's almost like dim sunlight..

that's the idea,
the government officials are all suffering from SODS (survailance obsession disorder) and need the light for all the camera's.
it's even in the marketing crap from the manufacturers.

[james_s]

Additionally, whereas they draw much less power, they have much more brightness, partly due to their specific spectrum but probably partly for marketing reasons. Some streets at night are so bright that it's almost like dim sunlight..

that's the idea,
the government officials are all suffering from SODS (survailance obsession disorder) and need the light for all the camera's.
it's even in the marketing crap from the manufacturers.

That seems to be a primarily British thing. There are some CCTV cameras here in the US but the vast majority are privately owned and not centrally monitored by big brother.

[SiliconWizard]

Not just british. It's becoming pervasive in most of Europe.

I believe there are also many in California.

[stj]

and people are sick of it.
https://camover.noblogs.org/
just one example.

[Eka]

• can not be retrofitted to discharge type lamps (they need a couple of minutes warm up before full brightness), therefore includes installation cost for new lamp type

Non issue. The economics of retrofitting a fixture fail big time. Much cheaper to just replace fixture and all. The LED street lights have so much less service calls for bulb replacements during their life they easily pay for them selves multiple times. In the US and Europe it costs a few hundred dollars to replace a HID street light bulb when you factor in the costs of the equipment and operator to do it. Don't need to do that service call once or twice and you pay for the new LED fixture. The savings will be more like 5 to 10 less service calls over the life of the LED bulb. I would be surprised if it was less than $1000 saved in service calls per year per mile of lit road for LEDs versus sodium vapor bulbs. That pays for lots of additional retrofits. Energy savings are not the reason to swap. HID bulbs are very efficient.

Bulb replacement costs in office buildings is driving retrofits and initial installs to LEDs. A T5 fluorescent has similar efficiencies, but needs replacement 5 to 10 times as often. You have to pay somebody to replace that bulb. It adds up.

[stj]

so what is the service life of an led lamp-head?
because a low-pressure sodium lamp lasts atleast 10 years.

[coppice]

so what is the service life of an led lamp-head?
because a low-pressure sodium lamp lasts atleast 10 years.

The quoted lifetime of LED lamp heads is usually very long - up to 50 years for some. However, design quality is highly variable, so what happens in the real world will only be found over the next 20 or 30 years.

[stj]

50years my ass, that's a fraud claim right there.
so unless the invertor/buck convertor has no electrolytics and the leds arent phosphor coated there is no way it will hit a decade IMO.
i know some types have already been replaced after only a couple of years.

[theoldwizard1]

The City of Detroit converted all of their street lamps to LED a few years ago.  Or I should say after almost 100 years, the City of Detroit gave up on trying to generate and distribute their own electrical power and handed it over to the local utility, Detroit Edison.  Most of the street lamps had not been operating for as long as 20+ years !  Some areas of the city actually had their street lamps wired in series !  Detroit Edison completed the conversion a few years back

One thing about the new LED street lamps is that the reflector creates a much smaller "pool" of light.  People in the neighborhoods noticed this, but nothing is likely to be done about it in the near future.

[james_s]

As I mentioned earlier, the small pool of light is due to dark sky regulations that mandate no light emitted above 90 degrees. In practice this means the luminaires mounted at typical heights produce a small pool of light. The older sag lens types spread the light much more evenly but also spray some small amount upward. This issue is not limited to LED sources.

[stj]

it's not just that, the reflectors are designed to be used at a specific height and spacing between lamps to avoid uneven spots or black spaces.
this probably gets ignored by the people buying and using them.

[james_s]

In many installations they reuse the existing poles for obvious reasons, poles that were designed for sag lens semi-cutoff luminaires. New installations often look cluttered with so many poles that it looks a bit silly.

[coppice]

50years my ass, that's a fraud claim right there.
so unless the invertor/buck convertor has no electrolytics and the leds arent phosphor coated there is no way it will hit a decade IMO.
i know some types have already been replaced after only a couple of years.

You know, we do build some electronics for a 50 year life, and actually achieve it with only a modest number of early failures. Life time is largely a cost/performance tradeoff choice. The issue will be whether people are prepared to pay what it costs to achieve a 50 year life.

I would have thought 10 years would be a more reasonable target life for most street lighting, to keep the initial cost down. Use solid caps and the right plastics, and that shouldn't be hard to achieve.

[james_s]

I have numerous electronic devices that are 50+ years old and still work, although most are not in continuous service and some have had capacitors replaced at one point or another. I do agree that 10-20 years is more reasonable for a streetlight though. By 10 years the optics will be filthy.

I have seen old mercury streetlights that had been running the same lamp for 30+ years though. Around the early 70s the lamp technology had been refined to the point that some of them actually lasted too long to be economical for the manufacture. There was an electrode composition for a while that made white inst as of black deposits in the arc tube and they stopped using it because the lamps were lasting too long. GE called them "Bonus Line" and Westinghouse used a similar design in their Lifeguard lamps for a few years.

[stj]

electronics can be made to last, but phosphor coatings still have a limited life.
if you want to use the old RGB method of white led light generation then maybe you can get a long life,
but using blue or UV with phosphor coatings - not happening - not yet atleast.

[SiliconWizard]

50years my ass, that's a fraud claim right there.
so unless the invertor/buck convertor has no electrolytics and the leds arent phosphor coated there is no way it will hit a decade IMO.
i know some types have already been replaced after only a couple of years.

Yeah, I don't buy it one second. I believe the power LEDs themselves are only rated up to a few thousand hours of operating time. Let's assume an average of 10 hours per day of lighting. You're going to reach EOL within a few years. Not to mention that they are subject to relatively high temperatures during daytime in sunny areas, which will likely shorten their lifetime further even if they are not powered at those temps. 10 years *max* is probably what you're gonna get with top-notch LEDs and designs.

As we said above, it doesn't even matter unfortunately (which is why those claims can be made without harming the companies that make them). It's close to 100% certain that those fixtures will be replaced every few years anyway for a number of other reasons (mass surveillance being one of them - and technology is bound to progress fast in this area in the coming years/decades).

[coppice]

electronics can be made to last, but phosphor coatings still have a limited life.

Do you have any information about that? I looked recently, and couldn't find anything. Flourescent tube bombard the phosphor quit e hard with heavy ions, and the best lifetimes are something like 10k hours. Electron devices bombarding with electrons get a lot more life, but eventually fade. What sort of life do you get just bombarding with not too extreme photons?

[james_s]

Well we already know that 10 years is achievable, the first LED streetlights I saw started going in around then and at least some of those are still in service. I think a 10 year lifespan is a pretty reasonable goal. When you figure most HID sources are relamped about once per 3 years and labor is the largest part of that cost, a 10 year LED luminaire is looking pretty reasonable. Claims much longer than that, well it may be doable but I wouldn't bank on it. There's s good chance whatever company sold them won't be around by then anyway.

[james_s]

electronics can be made to last, but phosphor coatings still have a limited life.

Do you have any information about that? I looked recently, and couldn't find anything. Flourescent tube bombard the phosphor quit e hard with heavy ions, and the best lifetimes are something like 10k hours. Electron devices bombarding with electrons get a lot more life, but eventually fade. What sort of life do you get just bombarding with not too extreme photons?

That's not an easy question to answer. "Lifespan" is normally defined as time before L70, i.e. lumen output 70% of initial. The decay is roughly a halflife and depends heavily on how hard the phosphor is driven, chemical composition, quality, etc. If you use a good phosphor and don't pump it too hard, it can last a very long time. Use a cheap phosphor like low cost 5mm white LEDs and it will fade in just a few months.

[stj]

the phosphor gets damaged by heat from the dye more than anything.

[SiliconWizard]

Speaking of surveillance cameras coupled to bright streetlights:

https://qz.com/1458475/the-dea-and-ice-are-hiding-surveillance-cameras-in-streetlights/