Why LED Street Lamps Are Better

Besides being fairly efficient and highly directional, LEDs are also extremely mono chromatic, which means it's very easy to filter their light out. A massive shift to LED street lights would not only save a great deal of energy, maintenance and disposal costs, it would also be a huge boon to amateur astronomers and observatories situated close to towns and cities.

The town of Tekapo in New Zealand has special local planning constraints on its street lighting out of consideration to the astronomers working at the local observatory at Mount John nearby (this observatory, incidentally, has contributed greatly to the assessment of planetary systems around local stars).

Alberto:

Thank you VERY much. That is a very useful analysis. You got a GA from me!

so far anything you need to know about LED's

just looking at the efficiencies for heat out put on these, as compared to regular streetlights

p911

Except for Stop lights. Citys such as Milwaukee, Wisconsin In the USA installed LED Stop lights. Which is Red (Stop), Yellow (caution Green to Red change), and Green (Go).

The problem is that where the traditional inefficent stop light emmitted heat, the LED emmitted less heat, summer its great, but the winter time this lack of heat does not melt away the snow like the old traditional ones, ssoooo.... the city has to sent out crews to brush the snow off and away from the lenses so you can actually see what color is showing.

guess ineffiencies has it's attributes.

p911

Yes, it is compromising safety for energy efficiency. They're going to have to supply an alternate heating source to keep the lights clear of snow and ice in the winter months, which will most likely negate the energy efficiency provided by the LED's themselves.

With anything there is always trade offs and you have to weigh the values, which is more important, safety or energy efficiency. My vote is to stick with safety.

http://www.ledsmagazine.com/news/7/1/4

seen this?

thanks for the link.

That helps and no one is challenging the cost savings issue. The wind screens will help. Drive into a driving blizzards.......yes some of us have to drive in blizzards. The Shields was an added feature due to unforeseen problem developments

Just have to see about the developments, I myself like LED's, and with the expense of installation of these LED's, you can bet that they will not be pulled and problems solved.

You beat me to it.

GA

The power supply is another important factor,should be not energy-saving,constant current to stable the light,and low temperature to prolong the life-span.

We all are aware that everyone does not live in a year round mild climate.

And, cold weather and snow makes LEDs very expensive and usage, but it all leads me to wonder what extreme heat may do to the LEDs life.

And they misinformed us.

http://www.ecogeekliving.com/compact-fluorescent-led-lights.html

and we have these precautions:

http://www.ledjournal.com/eprints/nextreme_sept09.html

So now we need this now:

http://www.freshpatents.com/Led-device-with-an-active-heat-dissipation-device-dt20070426ptan20070091622.php

Presumably LEDs are a prime contender for powering by photovoltaics ? In countries where the sunlight hours are high enough, for long enough

All I know is to never do business with www.ledroadwaylighting.com, they are the most unethical company in North America and you are giving your hard work to them for free to use for their own benefit. Watch out for this company!

As a guest, how do we know your not an competitor?........we don't

Another advantage not mentioned is that the spectrum of a white LED is pretty close to a black body - i.e. almost continuous. I've seen this using a diffraction grating. Compare that with the spectrum from a gas discharge tube or standard fluorescent light which basically looks like a few sparse lines punctuated by yawning gaps. That makes LEDs far better for colour discrimination.

Choosing between LED and HPS street lights NLPIP recently performed a formal evaluation of existing street-lighting technologies to determine the best choice between LEDs and HPS. Many municipalities are weighing the benefits of both LEDs and high-pressure sodium (HPS) as they consider their street-light options. The Lighting Research Center's National Lighting Product Information Program (NLPIP) formally performed an "apples-to-apples" evaluation of existing street-lighting technologies as detailed in its September 2010 publication Specifier Reports: Streetlights for Collector Roads. Established by the Lighting Research Center (LRC) in 1990, NLPIP has helped lighting professionals, demand-side management providers, contractors, designers, building managers, homeowners, and other consumers find and effectively use quality products that meet their lighting needs. The program has a demonstrated history of transforming the market and upgrading the quality, reliability, and energy-efficiency of lighting products by providing objective, third-party information to verify product performance compared to manufacturer claims. As is the case with all NLPIP publications, Specifier Reports: Streetlights for Collector Roads was designed to tell a story in an objective way. The report was widely publicized [see links to LEDs Magazine articles under Related Stories at right], but many third-party summaries and interpretations were misleading, so hopefully this article will clarify a few key points. Process To emulate the streetlight selection process used by typical specifiers, NLPIP purchased and analyzed eight LED streetlights that were recommended by manufacturer representatives as equivalent to an incumbent technology, namely a 150W HPS streetlight with a Type III distribution. Much to NLPIP's surprise, all six of the LED manufacturer representatives recommended streetlights with lower light output than the incumbent HPS technology. However, in order to most closely follow the typical specifier selection process, those were the street lights NLPIP purchased and evaluated. NLPIP analyzed the pole spacing needed for the streetlights to meet a national roadway lighting standard for collector roads, ANSI/IESNA RP-8. NLPIP then compared the streetlights' power demand and economic costs over a one-mile stretch of roadway. Results The report concluded that, on average, the recommended LED streetlights could use up to 10% less power, however, their life-cycle costs were higher. The LED street lights recommended by the manufacturer representatives would cost more than twice as much to own and operate as the incumbent technology over the life of the streetlights, primarily because the LED street lights required narrower pole spacings to meet the recommended practice for illuminating collector roads, and the cost of the poles per mile dominated the life cycle costs. A recent addendum to the original report examined LED street lights that could match the pole spacing provided by incumbent 150W HPS street lights. The results of the life cycle cost analyses are summarized in the chart below. Estimated life Average life cycle cost per mile of recommended LED streetlights Average life cycle cost per mile (excluding poles) of the "higher power" LED street lights 25,000 hours (6 years) 2.6X incumbent 150W HPS 2.3X incumbent 150W HPS 50,000 hours (12 years) 2.1X incumbent 150W HPS 1.7X incumbent 150W HPS The results of these analyses reinforce the fact that specifiers need to evaluate all available products, regardless of the technology, to provide their customers, as well as society, with the greatest lighting value. In many ways the LRC is grateful for the attention given to this report, because the overarching goal of NLPIP is to provide objective information to those specifiers. Without that attention, many specifiers would have remained unaware of these findings. Results Summary To meet the collector-road lighting criteria, NLPIP found that when compared to HPS, current LED street lights: • can save a modest amount of energy, and • usually have a greater life cycle cost, with or without the need for new poles Also, be aware that manufacturer representatives may recommend street lights that are not equal in performance.

seemly some very good information.....too bad its so hard to read.

I agree. The takeaways I get from it are 1)LEDS cost more to buy (otherwise putting the same number of poles up would probably equalize the cost overall, since the cost of streetlight installation is always in the hardware, with lifecycle cost driven by both that, and replacement/maintenance of lamp costs. But the replacement/maintenance costs are surely lower with LEDS, given their longevity when the thermal controls are properly engineered), and 2)the don't provide a wide-enough light dispersion pattern to provide the same coverage for the same positioning. I don't see any mention of light density, nor any mention of color-temperature comparison with HPS lamps, so I don't know if those factors figure in it, or not.

But I suspect it might still be early days in the development cycle, as the inherent directionality of LED emitters is being engineered from a number of angles, in the attempt to create, for residential use, a quasi-spherical distribution pattern, such as "conventional" (i.e., incandescent) lamps provide. Surely developments in that direction will apply equally to the needed hemispherical patterns for streetlamps, and the PAR floodlamp market. And I think the initial acquisition cost will have to come down as they achieve more market penetration, with the fix of the dispersion issues.

Time will tell. But I'm patient. I LIKE LED light, and will be happy to replace every light in my life with them. I DON'T like standing on ladders replacing lamps as often as I currently must do.

Hello everybody,

I wrote an article starting from the NLPIP study speaking of some innovative optics being developed who will help enhancing the Downward Street Light Lumens per Watt factor.

At the moment is still in Italian (sorry), but in the next days I will translate it into English.

Ciao.

http://ariannaled.wordpress.com/2011/01/05/ottica-astronomica-per-lilluminazione-stradale/