Comment by toomuchtodo | Hacker News Reader

Comment by toomuchtodo | Hacker News Reader

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The City of Chicago is funding a replacement of all it's sodium bulbs with LEDs solely off the energy cost savings [1]. I'm unsure what sodium lamps you're referring to that use a similar amount of energy as LEDs.

> The sodium lamps use roughly the same amount of energy

"The new LED lights will consume 50% less electricity than the existing High Pressure Sodium (HPS) lights. When fully implemented the new fixtures are estimated to save the City $10 million a year in utility costs. By consuming less electricity, the City is helping reduce its carbon footprint. LED fixtures last up to two-three times longer than HPS fixtures."

> cast a light quality that is better for both humans and animals

"Compared to HPS lights, LED lights make it easier to see the contrast between an object and its surroundings; so one can quickly and more accurately identify people, vehicles, road debris or other things on the street or sidewalk. The whiter light also enhances peripheral vision and improves the quality of video resolution"

[1] http://chicagosmartlighting-chicago.opendata.arcgis.com/page...

> The new LED lights will consume 50% less electricity than the existing High Pressure Sodium (HPS) lights.

Not sure how they're going to achieve that. LEDs produce 37 to 120 lumens/watt, HPS and LPS produce 50 to 160 lumens/watt. The sodium lamps lose out only because they are omnidirectional and a mirror is required to aim their light down, so some of the light is blocked by the lamp itself. But overall LEDs don't save 50%.

> Compared to HPS lights, LED lights make it easier to see the contrast between an object and its surroundings;

This is true, but it's a red herring. While that might increase safety in one regard, the light cast by an LED is very blue, which affects both humans and animals, making their bodies think it is still daytime. This disturbs the natural hunting and migration patterns of the animals, and more importantly, disturbs the sleep of the humans.

Sleep deprived humans are for more dangerous than ones that have a harder time detecting object edges.

Also, shouldn't we consider quality of life issues when making these changes, and not just efficiency?

> the light cast by an LED is very blue

For blue LEDs, sure.

LEDs today can be made to emit any color all the way up to pure white.

And when properly spec’d, light temperature is remotely configurable on the fly. Not so with non LED bulbs.

Nobody is going to “on the fly configure” color temperature of street lamps. It would add cost and complexity, be less energy efficient, compromise longevity, and is not a worthwhile feature in that context.

In practice, all “white” LEDs (even the very warm ones) consist of a blue LED + a yellow phosphor, and for efficiency reasons in contexts like street lamps the phosphor is never set up to absorb all of the blue light, which means that the intense blue glare inevitably is there clobbering people’s night vision.

It would be possible to make LEDs appropriate for street lighting, but the lighting industry does not currently sell them.

That's ONE way to make white LEDs. Another, more expensive but much better way, is to use an RGB LED and tune the driver to emit the color you want from the triad.

They're getting cheap enough now (insanely cheap, in fact) that it is now feasible to fit street lamps with them.

Imagine the use that could be had if you could change the color of street lamps on demand. Guide vehicles in an evacuation, direct police to a particular location by coloring a lamp red, or something. Direct ambulance by coloring a lamp blue. I don't know. Seems like it could be useful.

It's less about the LED being suitable for street lamps than it is about the lensing chosen to direct the light to the proper locations under the lamp.

> more expensive but much better way, is to use an RGB LED

This is better for displays (or maybe stage lighting, art projects, fancy effects, ...) but not better for standard room lighting, and definitely not better for street lamps.

Using street lamps as information sharing devices makes a cute 1 minute demo, and sounds cool to sci-fi fans, but in practice would be gimmicky and not very effective.

The actual light coming out of “RGB” LEDs necessarily has a quite spiky spectrum, because they overemphasize supporting a wide color gamut. They also include more short wavelength light than is desirable for nighttime use (compromising night vision). e.g. https://cdn2.goughlui.com/wp-content/uploads/2015/12/hue-def...

> It's less about the LED being suitable for street lamps than it is about the lensing chosen to direct the light to the proper locations under the lamp.

I’m not quite sure what you are trying to say with this bit. For best lighting, there would be more lamps spaced closer together, placed at lower height, orange in color and individually dim, and diffused and well shielded from the side. These are all features which would be helpful for any type of lamp.

Unfortunately, the LED streetlamps adopted by cities are high up, widely spaced, much too blue, extremely intense, and not shielded from the side.

> Not sure how they're going to achieve that.

Less lumens. The lighting industry has successfully scammed the public into buying less efficient LED lighting with greenwashing.

this

The availability of cheap overkill LEDs is making cities worse... It's especially noticeable when walking at night in areas with restaurants and nightlife.

It's not just street lightning, but also private buildings (maybe they're after that prison yard look?) and cars (giving pedestrians and drivers free lasik, nice!).

Maybe these are OK for highways, but this sucks big time for everywhere else.

They are just as terrible for highways. Getting hammered by blue glare in your peripheral vision is very distracting and destroys night vision, making it harder for drivers to see.

(For the same reason, LED car headlamps are horrifically bad for everyone other driver on the road.)

I don’t understand why there aren’t isn’t strict enforcement of laws about headlights yet. Do the police and politicians not see the danger themselves in the rear view mirror when they drive on the road?

> Do the police and politicians not see the danger themselves in the rear view mirror when they drive on the road?

They don't realize there's a problem, or they've just spent a lot of money "upgrading" their vehicle fleets and don't want to consider that they've been ripped off.

The vehicles of my local police departments and state highway patrol have had all their safe incandescents replaced with blinding LEDs. Flashing blue LEDs on the roof of the cars, flashing blue-white LEDs mixed in with the flashing red and blue LEDs, and blinding amber LEDs to warn of road hazards. The vehicles have blue-white spot lights, and sometimes they have blue-white light bars on to blind everyone within a quarter mile of the scene.

I think the police officers think their new lights are cool.

OSHA [0] should intervene, but I don't know that I can make a complaint on the police officers' behalf...

[0] https://en.wikipedia.org/wiki/Occupational_Safety_and_Health...

> Not sure how they're going to achieve that. LEDs produce 37 to 120 lumens/watt, HPS and LPS produce 50 to 160 lumens/watt. The sodium lamps lose out only because they are omnidirectional and a mirror is required to aim their light down, so some of the light is blocked by the lamp itself. But overall LEDs don't save 50%.

I did a quick search and found their RFI [1]. They are reducing electricity consumption by 50% because they are replacing 40+ year old light fixtures that have 70+ year old wiring:

> In the 1950s, the City installed new lighting infrastructure citywide; utilizing mercury vapor lamps. In the 1970s, the City performed a system-wide lighting upgrade; replacing the mercury vapor fixtures with high-pressure sodium fixtures. This project was only a lamp head upgrade; the City retained the 1950s era electrical poles, wiring, and infrastructure. Over the years as underground wiring has failed, City crews have often replaced underground wiring with aerial wiring. In 2009, using available federal funding, the City replaced high-pressure sodium streetlight fixtures with more energy efficient ceramic metal halide fixtures along Western Avenue and Lake Shore Drive. That fixture replacement undertaking did not include upgrading the electrical infrastructure.

[1] http://chicagoinfrastructure.org/wp-content/uploads/2014/10/...

The City of Chicago doing anything is not generally a good indication of that thing being a good idea.

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