LED Street Lighting Options

[PeterJ]

What are the alternatives to bright, white streetlights and why are councils not exploring them?

A (very) few local authorities have opted for reasonably warm and friendly street-lights but most just go for the ugliest and most intrusive glaring white ones. Clearly these are the cheapest, but how much more would it cost to fit something more pleasant?

It's not easy to find an answer to this question and I wondered if someone here would know. Heritage lighting and amber/yellow/orange LED models are available but what are the cost implications? It'll take my council ten years to break even on this installation program for 3000k white LEDs, so maybe the question is how many more years it would take to pay for a more environmentally-friendly and natural tinted or softer lighting option.

Any lighting engineers around?

[Patrick Harper]

Beating a dead horse.

[PeterJ]

I'm not beating any horses, just asking a question.

[Big L]

I'm not beating any horses, just asking a question.

22 posts, the majority of which are anti-LED or anti-councils that install them.

[PeterJ]

I'm not beating any horses, just asking a question.

22 posts, the majority of which are anti-LED or anti-councils that install them.

If you look carefully you'll notice that I thanked people for their contribution and moved on. This is a request for information.

Your strapline seems appropriate since I see these lights as the death of poetry. But I've had that conversation. Now I'm asking about alternative specifications.

[Northern Lights]

The technology has always been there. The company that my council bought 4000K LED lights from does "off the shelf" 2700k & 3000K versions, our council chose 4000K. In 2009 Braun installed Luxeon Rebel LEDs to match the 2900K of the vintage gas lights in Berlin. The council etc. made a conscious decision to keep the old style gas-light look.
So why are 4000K & 6000K LEDs used everywhere? To keep the explanation simple:- higher K colour temps are perceived as "brighter" than lower K colour temps by the human eye. This enables you to lower the output & wattage of the higher K LED to match the same perceived brightness as the lower K colour temp. Thus you save even more money on electricity consumption. Its like the argument between diesel & petrol. The diesel particulates were known about at the time, but everybody chose to ignore these & concentrate on the CO2 emissions. Being blinkered & focusing only on one part of the equation leads to more hidden long term problems.

[PeterJ]

Thanks Northern Lights. We seem to share a view on this.

My question is not about brightness so much as colour. Even 3000k lights a far too bright and painful on the eye, at least in rural and residential areas. So I was wondering what options exists for tinted and warmer lighting, and what the cost implications would be for fitting them.

I imagine the only cost would be a slightly higher energy bill. If so, then it would mean taking a little longer to recoup the installation costs. For my council this will currently be ten years. I wondered if more pleasant lighting would increase this to 12 years or 20, and whether there are other factors to consider.

[Big L]

...the ugliest and most intrusive glaring white...

My most insincere apologies for misinterpreting that phrase as a criticism.

[Northern Lights]

Thanks Northern Lights. We seem to share a view on this.

My question is not about brightness so much as colour.

You have just fallen into the same trap as everybody else....colour temp affects "percived brightness".....many people complain that the new LED lights are "brighter"...& in fact in many cases the LED lights are actually "dimmer" as the lm is less.

Take identical LED bulbs, all the same wattage, voltage, lm output, size, shape, LED type etc.. Howver have one at every 1000K increment to 6000K...so 1000k, 2000k, 3000k, etc...the 6000k will appear to your eye as much brigher than any of the others as the colour temp of 6000K contains more blue wavelength light regardless of LED construction. The human eye reacts to blue wavelength light as daylight as it triggers those daylight receptors. Basically high K colour temps trick our eyes..so the LED specifiers are abusing the human eye to fit a lower power consumption LED unit. The difference in efficienty is no more than approx. 20% between say a 6000K & a 3000K...& it varies A LOT depending on LED construction etc....some types have very little difference.

In my opinion, Road junctions, shopping malls, etc can have 6000K..but quiet residential streets need below 3000K..common sense...

[Patrick Harper]

I already addressed the issues with straying from most council's current strategies in the other thread, and here you're just repeating yourselves.

[PeterJ]

Thanks Northern Lights. We seem to share a view on this.

My question is not about brightness so much as colour.

You have just fallen into the same trap as everybody else....

I don't think so. I understand what you say above about power ratings but I'm asking about colour options. You're speaking about 3000k versus 6000k lighting but I'm asking what options there are regardless of the rating. Also, when I say 'bright' I mean 'appear bright to human eyes', so it wouldn't make sense to say they appear brighter but are actually dimmer.

Manufacturers make heritage lights and can supply yellow, amber and orange colours. It's these I'm asking about. This is a technical issue, not in any way contentious or political, that is not dealt with on my original thread and either someone knows the details or they don't. The question is about colour options. Some authorities have taken advantge of these and I'm wondering why it's so few. Presumably it's the cost implications and I'm wondering what they are.

I don't know why Big L is trying to cause trouble or why Skye cannot see that i'm not repeating myself. but perhaps my OP was unclear.

[exiled]

The SMT has become aware that this thread is once again turning into the M60 without the exits.

If it remains on a path of what appears to be purely circular comments, it will be closed. Between now an 1700 BST on Friday 21st June if no indication of a change in the nature of the debate, this will happen.

[AndyB]

Thanks Northern Lights. We seem to share a view on this.

My question is not about brightness so much as colour.

You have just fallen into the same trap as everybody else....

I don't think so. I understand what you say above about power ratings but I'm asking about colour options. You're speaking about 3000k versus 6000k lighting but I'm asking what options there are regardless of the rating. Also, when I say 'bright' I mean 'appear bright to human eyes', so it wouldn't make sense to say they appear brighter but are actually dimmer.

Manufacturers make heritage lights and can supply yellow, amber and orange colours. It's these I'm asking about. This is a technical issue, not in any way contentious or political, that is not dealt with on my original thread and either someone knows the details or they don't. The question is about colour options. Some authorities have taken advantge of these and I'm wondering why it's so few. Presumably it's the cost implications and I'm wondering what they are.

I don't know why Big L is trying to cause trouble or why Skye cannot see that i'm not repeating myself. but perhaps my OP was unclear.

A little explanation...

The colour of a light source is measured in degrees Kelvin (although at thousands of degrees, the difference of 273.15 degrees between and celsius isn't quite trivial). The lower the temperature (eg 3000K) the warmer and yellower, the higher (eg 6000K) the colder and bluer.

If you have a Digital SLR camera, it will have a colour temperature control, sometimes with presets, but essentially to neutralise the light source (for example, to add warmth to a picture taken under fluorescent light that would otherwise be very cold).

Does that help?

[Northern Lights]

I don't think so. I understand what you say above about power ratings but I'm asking about colour options. You're speaking about 3000k versus 6000k lighting but I'm asking what options there are regardless of the rating. Also, when I say 'bright' I mean 'appear bright to human eyes', so it wouldn't make sense to say they appear brighter but are actually dimmer.

Manufacturers make heritage lights and can supply yellow, amber and orange colours. It's these I'm asking about. This is a technical issue, not in any way contentious or political, that is not dealt with on my original thread and either someone knows the details or they don't. The question is about colour options. Some authorities have taken advantge of these and I'm wondering why it's so few. Presumably it's the cost implications and I'm wondering what they are.

Again you fail to understand.....kelvin or colour temp has nothing to do with actual brightness as measured with a light meter….& the colour look of the light is directly specified by a Kelvin (K) temperature number e.g. 3000K.

I am a full qualified Technical Architect, have studied lighting design & have been a very keen photographer for the past 30yrs so I have some idea about what I am talking about, so I'll try again to be clearer...


Take the same design of LED bulb, same wattage, same voltage, same LM (light output simply put, & LM is Lumins), same size, shape etc.....now have one at 1000K, 2000K, etc to 6000K....

1000K colour temp is red light....
2000K is usually called a "warm white" with a yellow white look to it
4000K is usually called "cool white" with a bluer look to it than above
6000K is called "daylight" with a blue white look which is colder looking than above.

https://en.wikipedia.org/wiki/Color_temperature

I am leaving aside the whole problem of colour rendering, or the CRI (colour rendering index)..this is more complex as you can have the exact same bulbs as above but for each seperate "K" rating you could have diffent colour rendering index values. Colour rending is the descripion of how acurate colours appear under that light source....ie does a white sheet of paper look white?

https://en.wikipedia.org/wiki/Color_rendering_index

The human eye responds to high K values & high CRI values as if it is daylight & uses those daylight receptors in the eyes...thus the light "appears" brighter than a lower K value & lower CRI light......so a 6w 6000K 90CRI LED will appear way brighter than the same bulb but with a 3000K & 80CRI spec..


I could confuse you even more & talk about glare & reflectance...

[PeterJ]

The SMT has become aware that this thread is once again turning into the M60 without the exits.

If it remains on a path of what appears to be purely circular comments, it will be closed. Between now an 1700 BST on Friday 21st June if no indication of a change in the nature of the debate, this will happen.

I don't quite understand the problem. I'm asking a technical and perfectly reasonable question that an engineer ought to be able to answer. There have been some unnecessary and rather inflammatory comments from someone who doesn't understand the question but I can easily ignore them. I could ask a manufacturer I suppose, but prefer to ask informally here. Please don't close the question before someone has answered it. There are people here who know their stuff on this topic. It is not my fault if some people prefer to argue with my view rather than address the question.

[PeterJ]

Again you fail to understand.....kelvin or colour temp has nothing to do with actual brightness as measured with a light meter….& the colour look of the light is directly specified by a Kelvin (K) temperature number e.g. 3000K.

Aha. Yes, I may be misunderstanding this issue.

So what you're saying is that these lights only come in one form and any perceived difference in colour is due to differences in K rating. If so, then the whole issue becomes a lot simpler.

Perhaps, then, I need to move on to asking about tinted covers and other ways of ameliorating the brightness and glare. Before doing so I'll see whether I'm still misunderstanding.

Thanks for your patience. I had no idea that one day I'd need to know about street-light specifications.

[PeterJ]

A little explanation...

The colour of a light source is measured in degrees Kelvin (although at thousands of degrees, the difference of 273.15 degrees between and celsius isn't quite trivial). The lower the temperature (eg 3000K) the warmer and yellower, the higher (eg 6000K) the colder and bluer.

If you have a Digital SLR camera, it will have a colour temperature control, sometimes with presets, but essentially to neutralise the light source (for example, to add warmth to a picture taken under fluorescent light that would otherwise be very cold).

Does that help?

Yes, thanks. I think I've just stopped misunderstanding something. I hadn't realised the only variable for these lights is the power rating. I thought colour was, or could be, a separate variable.

[exiled]

This thread is now locked subject to SMT and Cttee deliberation.

[ScottB5411]

It has been decided that this thread will remain permanently locked