Some problems with new LED street lights

Many communities have installed LED bulbs in public areas but the rollout hasn’t always gone smoothly:

For some, those first LED lights have been a fiasco. The harsh glare of certain blue-rich designs is now thought to disrupt people’s sleep patterns and harm nocturnal animals. And these concerns have been heaped on the complaints of astronomers, who as far back as 2009 have criticized the new lights. That’s the year the International Dark-Sky Association, a coalition that opposes light pollution, started worrying that blue-rich LEDs could be “a disaster for dark skies and the environment,” says Chris Monrad, a director of IDA and a lighting consultant in Tucson…

Lately, lighting companies have introduced LED streetlights with a warmer-hued output, and municipalities have begun to adopt them. Some communities, too, are using smart lighting controls to minimize light pollution. They are welcome changes, but they’re happening none too soon: An estimated 10 percent of all outdoor lighting [PDF] in the United States was switched over to an earlier generation of LEDs, which included those problematic blue-rich varieties, at a potential cost of billions of dollars…

Whatever their faults were, those blue-rich LED lights do save energy and money. My city of Newton, Mass., which has about 80,000 residents, expects to save US $3 million over 20 years after swapping its 8,406 sodium streetlights for 4,000-K LEDs, and avoid 1,240 metric tons of carbon dioxide emissions annually. Los Angeles anticipates saving $8 million a year after installing more than 150,000 LED streetlights, [PDF] while New York City hopes to recover $14 million a year by replacing the city’s 250,000 streetlights with LEDs.

Outdoor LEDs also illuminate streets more efficiently than sodium not so much because of their superior lumens per watt but because they are highly directional, meaning that they focus light mostly in one direction. Sodium lamps are gas-filled bulbs that emit in all directions. More than half of that light must be redirected downward by reflectors or lenses, reducing the lamps’ illumination efficiency.

It sounds like the solution is already at hand: swapping early LEDs for later ones that have warmer hues. Yet, this could serve as a cautionary tale of what happens when infrastructure changes: something that many people don’t pay attention to (street lights) suddenly changes and the world (literally) looks different. Of course, the savings are tremendous but infrastructure choices shouldn’t always be made solely due to efficiency: many residents also care about quality of life and have certain expectations about how things are lit.

While on this topic, it reminds me that I would like to eliminate fluorescent lights in buildings. Rather than use them in my office, I often don’t have my lights on. Maybe I’ve fallen prey to conditioning regarding enjoying yellower incandescent light. Given the changes in bulbs across all sorts of settings, we might all prepare for a future of harsher and colder light.

3 thoughts on “Some problems with new LED street lights

  1. I used to really like cold light, but now I’m leaning towards warm light, possibly as a overcorrection.

    As to LED lights and their possible successors (OLEDs, LECs, etc.) I welcome them even if there are some initial kinks to work out. They are by far more efficient than the predecessors.


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