UKC

All the sodium street lights are gradually being replaced around me with LED versions.

Apart from lower electricity bills, are LED lights better for the environment, especially regarding light pollution?

In reply to The Lemming:

I think the main reason is that of redundancy - if the bulb goes in a traditional light then the light doesn't work at all. Since there are multiple LEDs then if one goes it's only a fraction of the light output gone.

As for light pollution - that will be more due to the direction the light is pointing (hopefully downwards) and the diffraction effect given by the cover.

ALC

In reply to The Lemming:

I have these in my street, and I have to say they are no where near as good as the old (perfectly functional) lights. I understand the need to save power, but I can't understand why they couldn't just change the heads rather than ripping the whole thing out of the ground and replacing it - seems like a lot of money spent unnecessarily.

The main problem with them is the quality of the light, and the "whiteness" of the light - somehow it seems to be dimmer where the light is meant to be (on the street), yet brighter in my house where I don't want it!

In reply to balmybaldwin:

In Milton Keynes they are installing them, and they are just replacing the heads.

I think we "over-light" our streets in the UK. I've seen LED and fluorescent fittings in other countries that just provide a usable background light - we seem to think it should be daylight 24/7, which is a waste of money.

Neil

In reply to balmybaldwin:


Lamp posts corrode, they have a finite service life. Yours may not yet have been unsafe but they may well have required replacement within the life expectancy of the new lamps being fitting. Doing the job once saves money. Equally it may be that adapting new heads to several different post designs across the town is significantly costlier than simply replacing the (consumable) posts. Write to your council and ask them if you're genuinely interested.

jk

In reply to jkarran:
Yea here in Blackpool the old ones were concrete posts and no doubt they have suffered internal contrete cancer and were time expired even though they look sound. The new ones the Lemming refers to are shiney steel ones and the one outside my house was replaced about 3 weeks ago. It terms of light output they seem to give a much brighter light, glad we don't sleep in the front bedroom. I think I'll be able to service the car on the drive during night time now.

In reply to Neil Williams:
But "over-light" is handy for running at night without a headtorch, on that basis i'm starting a petition to prevent further rollout of LED street lamps.

In reply to The Lemming:

At least you could filter out the sodium band and still get a decent view of the sky.

Unless they also fit more efficient luminaires and paint the ground black then light pollution is about to get much much worse.

In reply to The Lemming:

Arguments about altered behaviour of nocturnal creatures aside, I'm not sure that "light pollution" is harmful for the environment in the same way as (say) chemical pollution.

The only people I hear complaining about light pollution are hobbyist astronomers (OK, professional ones too)

In reply to Blue Straggler:

Maybe it's not as harmful as chemical pollution, but it is one of those things that makes life a little bit worse for people. Add enough of them together and you have a good argument for gassing all the cities

In reply to The Lemming:
I think it's quite easy to collimate LED light output - this means the light will be focussed downwards rather than being emitted in all directions. You can contro, where the ligt falls much more readily. The electricity savings should be huge, but the initial costs are much higher. They should also last a lot longer.

There should be less light pollution if designed properly!

In reply to hang_about:

Controlling where the light ended up with older generations of street lights was pretty easy too. The problem is that nobody bothered to do it.

In reply to The Lemming: The council replaced ours last year and actually used sime sense. They altered the spacing and as a result we now have 2 posts in place of 3 and the street is still lit adequately.

In reply to balmybaldwin:


I note a light near where I live has a little shield that stops it shining into the adjacent house. Maybe you should complain to the council?

For me, the difference to the eye does match the photo and I do find the LED ones brighter:
http://sphotos-h.ak.fbcdn.net/hphotos-ak-ash4/219150_10150165725465689_3097...

The old light had no doubt been reversed in to by someone, so replaced by an LED before the rest here (now all done I think.)

In reply to geebus:

That seems way excessive. Less than a quarter of that light level would suffice.

Neil

In reply to Neil Williams: Perhaps, but most of the light seems to fall on the road and not in people's windows... unlike the old light which is shining directly into the camera and reflecting in one of the windows opposite.

In reply to EeeByGum:

True, though the bright white light is quite hard on the eye and would make it quite hard to sleep as it reflects off the road, while the yellow is far more restful.

Just because LED is low-energy doesn't mean we should be burning money - a very low light, just enough to ensure there are no dark corners, directed at the road and pavement should suffice to save money and to reduce light pollution.

Neil

In reply to Neil Williams:


Agreed, how light do we actually need it to be?! So long as I can vaguely see where I am going then thats fine by me.

In reply to geebus:

That looks like a bleeding flood light!!

In reply to Neil Williams:


Fair dos. Street lighting is a bit of an odd one really. Since it is not metered, no one really knows how much it actually costs. It is just an estimate. Whether LED lighting is really answer is probably anyone's guess although personally, I do like the directional element of it. We have just had a light put up nearby that lights the area within several hundred metres which is a bit of arse given that without it, my garden would be just dark enough to do a bit of suburban star gazing. As it is, there is no chance.

In reply to The Lemming:
They changed the lights in Nottingham and the new lights are really bright and seem to be very wide angled without much of a reflector to direct the light.
The very white light seems to destroy any night vision you acquire so the shadows seem darker.
I can see the councils liking the lifespan of the LED units, fewer lamps to change.

In reply to cap'nChino:

And yet, when I cut the power to all the street lights and go around wearing night vision goggles people treat me like a criminal!

In reply to The Lemming:

It might be just me but under sodium street lights I could never accurately judge parking spaces. What looked like a small space under sodium lighting looked huge during day light.

Even driving at night with sodium lights I'd struggle with depth perception with traffic.

However with LED lights I have no problem what so ever. Of the two options, I'd choose LED lights for night driving around town.

Remember that Human eye is pretty 'clever' and generally works much better at equalising light levels etc - while a camera tends to be a bit more 'true' as far as showing exactly how much light there is.

It's a good point about the direction in my picture, looking at it - you can see that the sides of the houses at the end of the street look brighter. While with the LED light there is a very clear cut-off, where it's noticeably darker after on the lawns.
Whether having defined bright areas giving relatively darker shadows is a good thing is another matter when 'safety' etc is concerned.

In reply to cap'nChino:

I heard a debate on the parliamentary channel ( I have trouble sleeping) where some councils had switched off most of the street lights to save money. Apparently there was no statistically significant rise in criminality or accidents!
(Unless you call Dogging criminal)

In reply to gethin_allen:

There seems to be a brighter is better mentality when it comes to lighting. The new high intensity headlights are an absolute menace to oncoming traffic, dazzlingly bright and completely destroy night vision leaving you almost blind on unlit roads.

In reply to The Lemming: Yes much cheaper to run, better colour rendition, virtualy maintenance free, and alot more control of dircection.

Sodium lights are old and expensive to run..

In reply to geebus: They can control them by remote, maybe. http://www.bbc.co.uk/news/uk-20308297 Or in this it says they can.

In reply to The Lemming: I've never really understood the design of street lights. They are all designed to hang or lean over the road. Yet all cars have lights? Lighting the pavements would be much more sensible which would require posts of only a metre high throwing light on the pavements.

One stretch of dual carriageway by me has so many lights you could land a plane on it, yet as you cross into the next borough, there is no lighting at all. Why would you need it? No pedestrians should be walking along there.

In reply to itsThere:
Different ones to the ones in Reading, but makes sense that they'd have that ability.

Would seem to make sense to maybe turn them down a bit after midnight and a bit later on weekends of something.

Personally, I do find it much more pleasant driving on a properly lit motorway or A-Road. Even more so when on a motorbike and most definitely when on a push bike (though wouldn't really go near a fast dual carriageway on a push bike at night given the choice.)

In reply to The Lemming:

Low pressure sodium are very efficient, more so than LED I had thought?

In reply to needvert: For low power (headtorch) LED is the way to go if you do it right. for high power they have reached a cross-over point, i would gess that the lifetime of an LED has swayed the council into new LED lights. I dont know the figures to back this up.

In reply to The Lemming:

Sodium lighting was brought in the 70's during the last UK oil crisis. The lighting was white before then. This is just the next stage in energy saving and makes sense. LEd's have been replacing the old lighting systems most other places and use significantly less power for the same light output

In reply to itsThere:

We were told that when they changed ours, they also said they would turn half the lights off in the wee hours, but they haven't yet and weve had them nearly 2 years. Regardless of them being more directional, the whiteness of the light seems to mean more light reflects into the front bedroom, which means even with thicker curtains it effects sleep. Luckily its just my spare room.

In reply to balmybaldwin:

As yellow LEDs are cheaper and seem to last longer than white ones, why not stay with yellow, I wonder?

The earliest example of proper LED street lighting I saw, in the Netherlands in about 2005, used yellow ones.

Neil

In reply to needvert:

Quite possibly - most street lights would have had lamps <100W, and it's plausible that the LEDs are of a similar order of magnitude. But; low pressure sodium lamps have been getting increasingly hard to obtain and therefore more expensive. I've also got a feeling they're particularly bad for the environment, although i'm not certain about that. Of course the reduced maintenance costs is a major factor as well.

In reply to Neil Williams:

Warm white (ie yellowish) light isn't as bright as neutral white, or cool white (blueish) for the same power output. Most places that can get away with it therefore use cool white lamps.

Incidentally daylight is beyond cool white in the spectrum, but daylight bulbs are usually pretty expensive.

In reply to victim of mathematics:

"Incidentally daylight is beyond cool white in the spectrum, but daylight bulbs are usually pretty expensive"

Full spectrum ones yes, but daylight "blue" ones are becoming annoyingly common. They do my head in, because my brain doesn't expect daylight without normal shadows etc, nor for it to be slightly dimmed compared with real daylight.

First Great Western and WH Smith are prolific users of the evil things.

Neil

In reply to Neil Williams:

FWIW, my house is now 100% LED GU10 spots, the tenner-a-go Philips ones which provide an excellent light quality and no discernible flicker.

I suspect I have low persistence of vision, though, as I find almost all cheap ones have a visible flicker. Same with all car tail light ones I've seen, they are really irritating.

The latest annoyance is that the decent independent cafe outside Euston station on the left has installed daylight-temperature cheapo LED spotlights, which fail on both counts and may well put me off going there in future.

Neil

This reminds me, when I was a kid if you gave street lights a hard kick they'd go out, and flicker back on some minutes later.

In reply to needvert:

Sometimes they seem to go our or light up when you go past them (i.e. change state). I've long wondered why this was, I suspect it has to do with a dodgy connection combined with mobile phone interference, perhaps?

Neil

We got them last year in our cul-de-sac.

I personally prefer the white light over the orange sodium.

They also auto-dim after 10pm going to about half-power which is a nice touch.