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 Post subject: LED - the road so far
PostPosted: Sat Dec 15, 2018 9:42 pm 
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Ok, as with most lighting functions LED has become the industry standard. With streetlighting its become so ubiquitous in recent years that discharge lamps will soon only be found on those dead end roads in industrial estates. Weve seen big changes before, but nothing as permanent on the landscape as this. I thought id start this thread to start a review on the topic and gain the opinion and knowledge of those with much more technical knowledge and experience than I. Firstly I need help with some simple questions about the advent of LED streetlighting.

What was the first LED street light to hit the UK market and when?

What was the first installation you saw and when?

In the area I live LED lanterns have been installed in small quantities over the last ten years, but in the last year or so been rolled out massively to replace all existing types.

My summary is below (please comment)

Pros -

energy use
white light
reduced maintainance
increased lifespan
reduced lantern size
dimming ability.

Cons -

Glare is a massive problem due to the tiny area that the light is emmited from. As someone that does 20000 miles a year, I have noticed this massively. It can be uncomfortable.

Light distribution - due to the lack of optical control is visibly poorer, often due to insistence on post top application.

Aesthetic design - design of some lanterns has passed functional and heading to 'downright ugly',

Obviously the biggest driver will always be the electric bill so I understand the motives, but can it be done better?

Would love to hear your thoughts

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PostPosted: Sun Dec 16, 2018 12:32 am 
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The first LEDs I saw on any road in my home town of Scunthorpe was in 2012 on Queensway, prior to this, the road had mostly SOX lighting, some of which was starting to show signs of end of life, then suddenly, when travelling down Queensway one evening, I find something looks strange, then I was surprised to see white lights instead of the then still usual yellow lights, the LEDs being Philips Lumas.

PostPosted: Mon Dec 17, 2018 7:57 pm 
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The first LED installation down my way was in Rockstone Lane in Southampton. In 2008, they retrofitted the existing cast iron columns with new post-top heritage lanterns containing the Philips Fortimo LED system. It was kind of a circular LED downlight that shone through a refractor ring. The LED fittings were rated at 45W, but the light output was shockingly bad. The lighting was by far the dimmest in the city, or anywhere really for that matter. Compared with the 42W PL-T and 45W CosmoPolis fittings being installed in the city at the time, they were significantly dimmer. At the time, I suggested that the LED was less efficient at producing light than mercury lighting. This installation was replaced only after a few years with a CosmoPolis installation as part of the PFI.

Another early installation was a trial of the Innolumis Lumis LED in Plymouth. In Plymouth, they used the 24W EcoWhite version on 5m columns on a footpath. These used a mixture of red and green LEDs. The theory was that green LED produced light at a point in the spectrum that was more in tune with the sensitivity of the human eye, so producing light in this colour enabled the most efficient output. By mixing in some red, a small degree of colour rendering was introduced. Blue light was considered to be inefficient, which was why they used green and sometimes red to generate light. I think the Plymouth installation was in 2009. I saw it with Phosco152, and compared with 24W PL-L, it was a lot dimmer.

There were a few experimental installations of LED in the late noughties, of which some used some unusual products that never caught on. The first LED fitting that went mainstream was the WRTL Stela, which was launched in 2008. I first saw these in the flesh in January 2010 in a trial installation in Bournemouth. This particular installation was 26W but the light output seemed comparable with 36W PL-L at the time, so you can see that literally over the space of about a year LED street lighting improved massively. Stelas were being updated and improved at regular frequencies, and the Bournemouth ones were considerably improved compared with those released at launch. This same year in 2010, LED started being trialled on main roads, and a year later in 2011 first appeared on the motorway network, with the Philips SpeedStar being one of the early choices.

To quote Urbis Saturn Land on the 18th June 2011, "I certainly do think that by 2021 (Twenty-Twenty One) that LED will be rather popular. SON well that will hopefully be obliterated, SOX banished, MBF gone but what's left is in private collections thoughout Britain. There may be pockets of MBF, SOX and SON but at least 90% of settlements (towns, villages) will have LED." This kind of feeling was mirrored by others once we started to see the improvements they were making to the technology.

As I said, 10 years ago LED street lighting technology was really in its infancy, and it was pretty rubbish. Oh how things have changed. We are now at the position where you cannot imagine anywhere with common sense installing anything but LED now. Mercury and SOX were on the way out anyway. SON has really fallen from grace and is no longer in favour. Compact fluorescent street lighting provided efficient white light, but has fallen out of favour on maintenance grounds. Ceramic metal halide is only about because of the use of SON lanterns. CosmoPolis now looks a bit idiotic, as it was a premium product that is no longer at the forefront of technology.

LED really has had perhaps the most dramatic impact since the introduction of the tungsten filament electric lamp. The thing is, it's not just street lighting; it's pretty much every application in which light is required.

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