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Some cities are taking another look at LED lighting after AMA warning

washingtonpost.com

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Re: Some cities are taking another look at LED lighting after AMA warning

#101

Post by jacobolus »

ptaipale wrote: post #97
jacobolus wrote: post #69

Earlier quoted context omitted.

> You are confusing ... I have spent 10 years studying color science. I know what color temperature is. I’m just explaining why the moon is a poor analogy. I have an issue with bright short-wavelength light sources at night, regardless of lamp configuration. It knocks out night vision. There is a wide literature (dozens if not hundreds of research papers) on this topic. It’s not exactly some deep mystery. The lamp co…

Do you mean that there are places where street lights with other technologies are replaced with LEDs by leaving every other lamp post empty? That is a problem that LEDs could enable (by making very bright lamps available) but is not really a problem of LEDs but a problem of using any bright light source wrongly. My understanding is that the use of lower-energy and more durable light sources provide most of the incent…

They rip the poles out, and replace them with fewer new poles (taller, wider spaced, with brighter lamps).

This makes the installation cost more attractive to the city.

The electricity bill is (potentially) lower if you replace very old lamps with LEDs at the same brightness.

The best sodium lamps are quite efficient though, so LEDs have only marginal advantage compared to replacing the old lamps with newer sodium lamps. If you make the LEDs dramatically brighter, then they actually end up using more electricity.

I haven’t seen any especially convincing numbers about an LED lamp project that saved on electricity bills. I’m not an expert in the subject though, and I haven’t looked too deeply into digging up data.

Re: Some cities are taking another look at LED lighting after AMA warning

#102

Post by pYQAJ6Zm »

keenerd wrote: post #30
jqkeller wrote: post #22

I've worked on a few street light retrofit projects and the AMA warning is a little overblown and frankly immediately outdated. This is off the cuff, but it comes down to circadian rhythms being influenced by the color of light. Before artficial light, the sunrise and sunset have a softer light with a lot more red wavelength in it. This would correspond more closely with the color of light from an incandescent, like…

> I think daylight is like 15,000K. No, it is 5500K or 6500K depending on which metric you use.

I always felt confused between the 5500 / 6500 K pair. What metrics are involved?

Re: Some cities are taking another look at LED lighting after AMA warning

#103

Post by dpark »

convolvatron wrote: post #94
dpark wrote: post #46

Earlier quoted context omitted.

Citation? That's a bold claim. As phrased, it also sounds really far-fetched since cataracts are not a disease of the retina. Maybe that's a problem with the phrasing and not the claim, though.

just look up 'welders eye' or 'corneal flash burns' or 'photokeratitis' high intensity UV light most certainly causes both corneal and retinal damage, both acute and as an ongoing effect over time. i have never seen nor can i find any reference to visible blue light. i think* that heavily phosphored leds with high CRI and low color temp do emit quite heavily above visible and translate it down. so maybe there is some…

No one disputes that sufficient light can damage the eye. The question is whether there's any evidence that LEDs cause damage to the eye sure to the higher percentage of blue light.

The fact that exposure to extreme amounts of light can damage the eye is not evidence for the claim that LEDs at typical brightness damage the eye.

Re: Some cities are taking another look at LED lighting after AMA warning

#104

Post by Senji »

fian wrote: post #34
keenerd wrote: post #29

Let's break down their claims. > unseen blue light I have unread negative comments about this sloppy writing. They also repeatedly use the word "intense" incorrectly. Intensity refers to candela. Not lumens or temperature. > The original LED streetlights had temperatures of at least 4000K, which produces a bright white light with a high content of unseen blue light. 4000K is actually considered fairly mellow. Above 6…

> Moonlight is around 4100K. So it is even more "natural" than 3000K. Should we blot out the moon next? I was on a hike in July during a full moon and those who were sleeping in open air (no tent or bivy bag) struggled to sleep through the night due to the moonlight. This was in the North West of Australia, so daytime maximums were around 35C. It was too warm at night to zip your tent or bivy closed, so where possibl…

>Should we blot out the moon next?

Why not? Lets fund an orbiter to create an artificial lunar eclipse exactly on full moon.

Re: Some cities are taking another look at LED lighting after AMA warning

#105

Post by phasetransition »

theatrus2 wrote: post #79
jacobolus wrote: post #72

Earlier quoted context omitted.

Some LEDs have phosphors which almost entirely absorb the light from the diode.

For example, Lumileds PC Amber and Lime LEDs employ this trick. They're usually used as a corrective color component and not the main lumen source.

I've not seen the PC Amber data from Lumileds, but I can vouch that their lime color LED has no blue diode emission peak visible in the spectra.

Re: Some cities are taking another look at LED lighting after AMA warning

#106

Post by pasbesoin »

keenerd wrote: post #29

Let's break down their claims. > unseen blue light I have unread negative comments about this sloppy writing. They also repeatedly use the word "intense" incorrectly. Intensity refers to candela. Not lumens or temperature. > The original LED streetlights had temperatures of at least 4000K, which produces a bright white light with a high content of unseen blue light. 4000K is actually considered fairly mellow. Above 6…

Noticed in my parents' town with their recent deployment. The LED lights appear to be more tunable and/or actually tuned, to put light on the street while keeping it off of houses.

So, "blue" whatever. If you are keeping my yard dark so I don't have to pull the shades just to block out the light, well, win!

Of course, other areas that still feel the need to light up every square centimeter because security, YMMV.

I'll add that I find the current LED streetlight colors better than the orange sodium vapor "malaise" that we've grown so accustomed to.

Re: Some cities are taking another look at LED lighting after AMA warning

#107

Post by mtalantikite »

keenerd wrote: post #76
mtalantikite wrote: post #71

I had LEDs installed in the streetlight in front of my apartment in Brooklyn a few months ago and my living room is now awash with this light. It's terrible. I noticed my sleep time pushed further and further back and I've resorted to supplementing melatonin regularly so that I can fall asleep earlier than 2 am. I've complained to the city and have considered moving since I don't think NYC will swap ours back.

Please, put in blinds. If you have blinds, put in curtains to catch the light that spills around the blinds. If too much light goes through the blinds, upgrade to window shades. If that isn't enough (or you don't want to spend any money on interior decorating), get an eyemask. If $2 for an eyemask is too much, drape a t-shirt over your eyes. Moving is a comically inappropriate response.

I don't find it unreasonable to want to have my curtains and windows open after sundown.

My bedroom is at the back of the house and feels like a cave, as is common for NYC bedrooms, so it's not the light in my eyes that is the issue. Having a delayed melatonin release due to the light is more my concern.

Re: Some cities are taking another look at LED lighting after AMA warning

#108

Post by mtalantikite »

rbanffy wrote: post #99
keenerd wrote: post #76

Earlier quoted context omitted.

Please, put in blinds. If you have blinds, put in curtains to catch the light that spills around the blinds. If too much light goes through the blinds, upgrade to window shades. If that isn't enough (or you don't want to spend any money on interior decorating), get an eyemask. If $2 for an eyemask is too much, drape a t-shirt over your eyes. Moving is a comically inappropriate response.

If moving becomes a common response, we can use street lighting to fight gentrification. Don't discourage it.

That's assuming city services go to all neighborhoods evenly, which certainly isn't the case unfortunately. Most of Brooklyn is covered now, but only 1/3 of Queens and none of The Bronx other than highways have been converted.
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