I saw loads of LED street lights in residential streets in Longton near Preston. They had two outer rows of 8 LEDs angled outwards, and two inner rows of 6 pointing down. They were retrofits to existing standards. They were rubbish. Practically no light reaches the paths and gardens of the properties so that must make the burger happy. I saw two faulty ones and the area they cover got zero assistance from their neighbours. One road junction was pitch black as a consequence.
A lot of people say the led lights generally are not the right colours yet. If usee up close the so called white ones are good for helping with lo vision as the light is purely reflected from the object, but in the case of outside lghting they apparently look hazy, maybe due to some effect on the eye of the ability to see the source, I'm not sure, but its a milar problem with some other types as well. Brian
Had them for a couple of years. In our case these are LED lanterns, not retrofits. (I've seen the retrofits at lighting shows, but not anywhere in service yet.)
As you say, light is directed to the road surface only - nothing else gets lit, although they did move all the columns back to the rear of the pavements, so perhaps half the pavements are covered too.
Lighting level is much lower than the mixture of various old low powered discharge fittings we had (mercury, SON, and SOX).
So far, the LED lanterns haven't come close to the zero maintenance claimed - failure rate has been too high. Failures I've seen are the whole lantern heads flashing continuously at something like 5Hz (I presume the PSU has died), or some portion (half or third) of the LEDs gone out or very dim (presume an LED in a series chain has died) or one or two LEDs gone out (again, assume they've died and shorted). One of the ones in our road spends about 5 minutes flashing on and off like a switchstart fluorescent, before it finally stays on continuously, and it's been like that since day one.
I notice in other areas of the town, they are no longer switching to LEDs, but rather to fluorescent tubes for new lanterns, which when unlit, look like they would be a SOX (low pressure sodium) lantern.
Recently, I've also seen a number of much more powerful LED lanterns for A-road lighting being installed. Again, these have been at lighting shows for a couple of years, but I'm only just starting to see them in the wild.
If you want light on your path or garden, fit one. I'd personally rather street lighting just lit the street, as I hate the way I'm kept awake by street lighting that wastes energy lighting the upstairs bedrooms of my house. (Yes, I could get blackout curtains, but then I like being woken up by sunlight in the morning as is natural).
I hope we get them here as soon as possible. FWIW, I've seen them in use in the Netherlands (yellow LEDs) at least five years ago and they seemed a good idea.
Yellow LEDs? That seems a retrograde step for street lighting given the move away from LP sodium in spite of it's efficiency.
As for lighting the properties, I agree totally that the direct beam would be a nuisance, but a little penumbral light is a good thing and many modern traditional street lights seem to have got this right IMHO. It's not too much to ask that the local authority endeavours to keep its tax and rate payers, and their properly, safe.
If anyone has read David MacKay's book 'Sustainable Energy' which is available free online
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he gives the following figures for bulb efficiency:
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Bulb type efficiency (lumens/W) incandescent 10 halogen 16-24 white LED 35 compact fluorescent 55 large fluorescent 94 sodium street light 150
Table 9.5. Lighting efficiencies of commercially-available bulbs. In the future, white LEDs are expected to deliver 150 lumens per watt. =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
Actually the original large scale low pressure sodium lamps have the highest efficacy in terms of lumens per watt of any production bulb.
The big ones can get to 200-220 lumens/watt. The colour rendition is obviously lousy but there is a lot of light output and soft shadows. They are so efficient that UK designers often let 30% of the light go skywards - Belgian ones have reflectors behind the bulb.
HPS which is now more common are more compact peachy white and efficacy of about 150 L/w.
UK should be cool enough that they will not cook themselves. They are a step backwards in white light luminous efficacy compared to HPS at present. The colour ones for traffic lights are better behaved.
That is so - but the subjective light output as installed wasn't great. Remember they were in the days before we expected to turn night into day.
But a much better light quality.
'Coloured' LEDs are quite satisfactory. It's the 'white' ones which are rubbish at the moment. Although to be fair I can't say I've actually seen LED street lamps yet.
Yes, I hate that. Our old street lights sprayed light all over the place - If I heard a noise outside at the front there was no point in trying to look out as I'd be illuminated and also couldn't see anything.
All of the luminaires in the village have just been changed - twice! The first were T5s by the look of them and still sprayed light; the second (about a week later) are 5-loop CFLs and the direct output is only just visible from my bedroom window. It's much dimmer in the room and I can see the front garden and road now.
Indeed they have, just round the corner, though 80% of my town's 'small' street lamps have been replaced with CFL types.
The money that must have been spent is colossal, because not only have the lanterns been changed, but the whole lamp post. A few had had it, but most were still absolutely fine, and often identical design to the ones they've been replaced with. The lamp post outside my house was only four years old, but still replaced with another brand new one !
Also, they still seem to be under photocell control, but there also seems to be a layer of remote control (3G ?) because some evenings all the lamps in my immediate area don't come on until 2 or 3 hours after sun set ! Conversely I've seen them all running in broad daylight at lunchtime. I know the ultimate aim is to switch them off in the dead of night, but whatever technology they're using seems troublesome !
Whatever, the CFLs are no where near as bright or effective as the bright yellow sodium (whatever type they're called) we used to have.
Hi-Bay LED lighting has been around for a while. The ability to produce well directed light from LEDs really helps here - they could be less than half the light output of a 400W mercury or SON lamp, but because that's all going exactly where it's required, the lumen level may not be any lower. Good colour rendition doesn't usually matter for this application either, so that can be dropped in exchange for better efficiency LEDs (which could still be better than SON's, for example).
Fair point. I just think street lighting, now decent technology is there, should concentrate on lighting the street, while I'll decide for myself if and when I want any lighting on my property.
For reasons of energy efficiency, we could really do with stopping those days in street-lighting terms. Most countries don't go for the same intensity of lighting as the UK does - Switzerland, for example, seems to use normal fluorescents in street lighting, and while it gives quite a dim light (though a decent white one) it is to me adequate to fulfil the safety/security role without also acting to keep people awake.
That said, half the ones by me are still sodium - the trouble is that they're the lantern type that send most light horizontally. The newer ones on the other side are downlighters, and while brighter they send more of the light downwards than into my window.
I've only seen (high-intensity yellow[1]) ones in Holland (Den Hag) and I think they were fine.
[1] Those seem much more reliable than white ones.
Hello Everyone, I run a blog about LED lighting, and I can assure you that LEDs are better quality than what some of you suggest.
The problem is that cities, municipalities, districts, towns, etc. are often sold crap straight from China. I can guarentee that if a professional company had looked at the street lamps and sold your city what they actually required, the results would be outstanding and much different.
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