We're Squandering LEDs' Potential to Save Our Night Skies
I explored London and Paris to see how LED streetlights are worsening light pollution despite their efficiency. While LEDs offer precise control to reduce glare and protect health, we often just install more of them, creating a Jevons paradox. Instead of smart, dimmable lighting, we are replacing old bulbs with brighter ones, harming our circadian rhythms and obscuring the stars.
The more bad light we add, the more bad light we think we need. We can't see because of the light we've added. And it makes areas that were perfectly okay seem darker.
- uv-depression
Greenhouses here in the lower mainland of British Columbia have been devastating to the night sky. It's quite depressing how little society values the night sky, something that's been an important part of every human culture for longer than recorded history. I've taken friends out to thoroughly mediocre skies (Bortle 4-5) and they've been very impressed, because they're used to city lights (Bortle 9) where you can maybe see a few of the brightest stars and planets.
If you've never seen truly dark skies, do yourself a favour and go see what they look like during true night. Bring binoculars if you have them, maybe get a planisphere and a (dim!) red flashlight.
The lack of respect for the night sky includes starlink and the other internet providers dumping tens of thousands of satellites in orbit instead of building municipal internet, by the way. It's been a huge hit to the field of astronomy. Before someone inevitably says "we should just be putting telescopes in orbit", orbital observatories are obviously a huge deal and I support building more of them, but you simply can't put things like the ELT (40m primary mirror, 2800 tonnes) or the Square Kilometre Array in space.
- Loic
Where I live, we have a small park, 500m away. You need to walk through it if you want to get to the city center from the small neighborhood we live in. To protect the wildlife, the lighting system has presence sensors, so as you walk or bicycle through the park, the way/street lighting turns on, you can walk, and just after you, it turns dark again. Really cool, especially the first time I went through it in the middle of the night.
- michael1999
We need much better engineering standards if we are going to fix night lighting. A simplistic lux-on-the-ground measure combined with cost minimization produces a few lights, with bare bulbs, up hight, with brutal intensity. These are all things that produce glare directly on the eyeball.
You need much less light on the ground if the eyeball itself has no direct line to the hottest part of the lights. Instead, the night-blindness caused by excessive bare lighting is "fixed" by adding more fill lights for the shadows caused by the first lights. Classic addictive behaviour.
- michaelt
I once lived in a city that had replaced street lights that cast light in a circle with modernised ones that cast a sharply delimited rectangle of light on the road, and didn't waste light in other directions.
The thing was, the roads of this city were arranged as a footpath, then a grassed area with trees, then the lights, then the roadway. Only after the city had rolled out thousands of these lights did someone notice the footpaths were now much darker. And also the footpaths were quite uneven, due to the trees' roots - a problem the lights had previously been keeping under control.
It's now common, in winter, to see groups jogging on the road.
- dwoosley
> “… gives the illusion, without the reality, of safety”
This actually isn’t true. Having done physical security work before, a weird fact is that one of the best physical deterrents is lighting; even over CCTV.
I don’t say that to take away from this, this is great work and I’d love to see the lighting toned down for multiple reasons. However, this should be framed as a security tradeoff not an outright win.
Source:
The Impact and Policy Relevance of Street Lighting for Crime Prevention: A Systematic Review Based on a Half-Century of Evaluation Research (https://www.crimrxiv.com/pub/wl9zqxga/release/1)
- dgellow
> Thorp notes that modern CCTV cameras are “pretty great” even at low-light levels, while harsh light makes it hard for both human eyes and digital sensors to see.
That’s a weird thing to include. That sounds like an argument _for_ more aggressive lights. I didn’t expect to see a “think of the surveillance system”
- binarymax
Our city recently went on a crusade on replacing all of the high pressure sodium bulbs with LEDs, with the justifications of driving safety and energy savings. I agree that these are important, but the LED bulbs they chose are actively hostile to homes and pedestrians. They are blinding. You can't look at them. I have one outside our house in the main viewing angle and we need to close our shades as soon as they are turned on.
- miladyincontrol
I think people focus far too much on the temperature of LED street lights and rarely on the CRI. The night will still feel odd and "soulless" even with 2700k LED street lamps so long as they're still the absolute worst CRI.
Dare I argue even I would choose 6500k LED street lights with decent CRI over poor CRI 2700K LED lamps any day.