A hope for less LP in future

[bojan]

Well, it seems it is going to happen: http://www.news.com.au/breaking-news/national/led-streetlights-to-be-used-in-nsw/story-e6frfku9-1226691244506

LED light is easy(er) to filter out..

[alocky]

It would be even better if these bulbs were designed in such a way as to limit how much light they direct sideways and upward. Where can one see a spectrum of one of these lights? I thought led have a broader emission than fluorescent or incandescent?
Cheers,
Andrew

[bojan]

White LED spectrum is just 3 narrow(ish) lines - R, G, B. http://en.wikipedia.org/wiki/Light-emitting_diode.. but this depends on the design. If it is a blue LED with phosphor, then we are in trouble!.
And LED light beam is quite directed by design, compared to traditional bulbs (which are omnidirectional)..

Of course, it depends on future and (non)existing regulations for street lights and their emission spectrum.

[rustigsmed]

I am interested to see the outcome of this event
http://www.lightingconference.com.au/?q=News&id=b7a75d3f-ab3f-f3fe-700e-51d3a7466b36

Ian Dryden (industrial designer) at Melbourne City Council has been trialling a variety of LED street lighting for years. You may have walked passed them on Riverside Quay, Southbank.

It is likely that the results of this may be reflected in Melbourne City Council's lighting strategy. They have been testing a variety of LED designs, outputs, reliability, hues and manufacturers (German, Australian and Chinese) etc.

The results of Ian Dryden's work at Melbourne CC will likely influence any Australian Standard for LED streetlighting and most local Councils across Australia and Europe. His street furniture designs are designed for Melbourne but are these days used all over Europe.

Cheers,

Rusty

[JB80]

I was under the impression that the white LEDs can't be filtered out at all. A white LED isn't exactly white and it covers the whole spectrum or something along those lines.
I don't think it's good news for imagers, maybe those doing visual if they managed to install them correctly but there have been some horror tales about the LEDs in the past.

I think it's one of those things that if implemented correctly could reduce visible pollution domes but it specifically hits the deep sky guys and may only leave narrowband as an option.

I'm prepared to be wrong on this but everytime I see LEDs mentioned there tends to be a kerfuffle.

[Steffen]

White high-intensity LEDs are almost always blue (or shorter w/l) LEDs using phosphors to make whitish light. In that way they are similar to fluorescent tubes and their wide, jagged spectrum. RGB LEDs are likely way too expensive, and I think not even possible yet at the required light output.

Maybe we can convince the councils to use red LEDs for street lighting ;)

Cheers
Steffen.

[rustigsmed]

most of the examples i have seen of LED street lighting they have atleast been designed to be well directed and actually light the street and not everywhere else. glare and light spill 'should' be reduced dramatically.

[multiweb]

That sounds great. Directional lighting. Finally. :2thumbs:

[Camelopardalis]

62 lights!? That's not very many.

LED street lights are an improvement in the sense that the light hugs the ground a lot better but it is still quite bright below the light level. My home town had these fitted a couple of years ago and so long as you kept below the garden fence, the (northern) Milky Way was quite prominent and you could even get decently dark adapted. Then a year later the local council decided to experiment with partial switch-off during the night. That made just as big a difference, as you could then see relatively faint objects much closer to the horizon, almost like being at a dark site :D

But that's a small town in rural England. In a big city like Sydney or Melbourne? It'll make a difference, it just remains to be seen how much, there are just so many other sources of light that aren't well controlled. The street lamps around here seem to have fairly directional white lighting...not sure if it's LED or not and it's not too bad, they are well spaced (unlike in England where they are about every 100-150m!) but there is still a residual white glow all around. Hopefully they'll jump onboard with that kind of potential saving.

Given the astronomical heritage of this country I'm surprised light pollution doesn't seem to be regulated at all - the way it is now, they'd probably be able to make more money from that than they do from speeding fines ;)

[rustigsmed]

For those that are interested here is the Melbourne City Lighting Strategy - as mentioned in my earlier post other council's will follow with similar strategies:


http://www.google.com.au/url?sa=t&rct=j&q=melbourne+city+council+lighting+s trategy&source=web&cd=3&cad=rja&ved=0CD0QFjAC&url=http%3A%2F%2Fwww.melbourne.vic. gov.au%2FAboutCouncil%2FPlansandPub lications%2Fstrategies%2FDocuments% 2Flighting_strategy.DOC&ei=hzcDUo76EuyYiAefqYD4Cw&usg=AFQjCNEIMhditkD2l32HSoZfJ6H3QHa Zow

i'd thought i'd highlight some parts of interest:

4.2.2 Use blue-white light in residential areas.

Replace yellow lamps and old “mercury vapour” light sources with new blue-white lamps. Install advanced technology with energy efficient lamps and full cut-off fittings.
• Blue-white light is softer and less intrusive than white light.
• Residential streets attract fewer pedestrians after dark. Therefore, a lower performance specification is justified.
• With present “metal halide” technology, the sources of blue-white light are more efficient than white light sources.


Blue-White Light Blue-white light is a “cool” white light, produced from lamps with a Correlated Colour Temperature of at least 4000K. It has a minimum Colour Rendering Index (CRI) of 80. The Lighting Strategy requires sources of blue-white to be energy efficient, and to be housed within full-cut off lanterns. With present technology, blue-white light is produced from Metal Halide lamps.

6.1.1 Reduce skyglow and other nuisances caused by obtrusive external lighting.
Ensure new outdoor lighting installations conform to Australian Standard AS 4282 (1997): Control of the Obtrusive Effects of Outdoor Lighting. Select lanterns that offer precise control over the distribution of illumination. Reduce upward waste light from streetlights by replacing semi-cut-off fittings with full cut-off designs. Minimise the component of light that reaches the sky from advertising boards, retail premises and outdoor sports facilities. Discourage indiscriminate floodlighting of buildings and open spaces. Instead, target illumination carefully so as to avoid stray light. In particular, minimise the quantity of light directed above the horizontal plane. Where up-lighting cannot be avoided, restrict this to narrow precisely targeted beams.
• Skyglow is increasing, and threatens to obscure views of major constellations such as the Southern Cross.
• Obtrusive outdoor lighting becomes more problematic as the central city’s residential population increases.
• Excessive illumination of isolated buildings or spaces degrades the ambient lighting environment, and produces discomfort for viewers.

6.1.2 Adapt streetlights to prevent illumination spilling into adjacent dwellings.
Acquire a range of specialised reflectors for use inside full cut-off fittings. Pay close attention to the distribution of illumination in residential streets. Where necessary, direct illumination away from the windows of bedrooms and living areas.
• Intrusive outdoor lighting can disrupt people’s sleep.
• As residential areas become more built up, foliage and verandahs are not always able to protect dwellings from unwanted light.
• In multi-storey developments, first and second floor openings are more likely to be subject to light spill.

6.1.3 Consider the environmental implications of new external lighting installations.
Address the effects of stray or obtrusive light as part of the development approval process. Request applicants to report on the environmental impacts of outdoor illumination whenever their projects are likely to have a major effect. When evaluating proposals for external lighting on buildings, balance the benefits of well-lit vertical surfaces against the negative effects of intrusive light. In parks, gardens and other large areas of landscape, consider the impact of night lighting on plants and animals. Review decorative lighting schemes on a case-by-case basis. Consider exempting these projects from obtrusive lighting controls, provided the duration of the display is limited.
• There is growing public concern about the effects of intrusive light.
• Conflicts between public lighting objectives and private lighting initiatives need to be identified before new installations are built.
• Environmental impacts are linked to the location of light sources and the direction in which illumination is emitted. Light sources that produce a large component of horizontal or upward light are more likely to cause nuisance.


6.2.6 Promote a review of Australian lighting standards to take account of new lighting technology.
• The optical performance of modern metal halide lamps is better than that of earlier technology. Therefore, it may be possible to reduce the minimum levels of illumination required in streets and other public spaces.
• A reduction in minimum illumination levels can lead to energy savings and reductions in skyglow.
• The City has considerable experience in designing and operating public lighting. This knowledge can inform national standards and practices.

6.2.7 Evaluate all new public lighting projects in terms of environmental sustainability criteria.
Consider energy efficiency and greenhouse gas emissions. Use measurable criteria, whenever possible. Employ these criteria to define project objectives, assign priorities, and assess funding applications. Ensure that systematic post-completion evaluations of performance occur.

[Terry B]

I've taken spectra of LEDs hoping to find emission lines to use as a cheap source of calobration lines. Unfortunatelly they all have a broad continuum so would be as difficult to filter out as incadescent globes.
They might have a better direction though so scatter upwards less.

[Steffen]

Exactly, especially since they're shooting for high CRI. The higher the CRI the closer to a continuous (incandescent) spectrum the light becomes.

That'll be the end of LPR filters. Hopefully the overall reduction of light scattered into the sky will make up for this.

Cheers
Steffen.

[JB80]

Here, bloody here! :D

I'll drink to that.