March 20, 2008

Lunar-Smart Streetlights
Miami Beach, United States

The sodium vapor streetlights on the road outside my hotel never turn off—middle of the day and they're still on, needlessly. It would seem the photo-sensor mounted to their fixtures (designed to turn the lamp off during the daylight hours) isn't working so well.

An excessive amount of ambient light pollution is just one item on a large list of personal annoyances that plague densely populated areas. It depressed me to no end to look up into the sky at any time of night in Lima, Peru and see the ever-present evening twilight of pale orange light, refracting back off the fog and clouds, or drowning out all the stars on even the clearest of evenings. Looking to the horizon there was always an amber glow, a depressing amber glow reminding me that I was lost inside a labyrinth of concrete homes and avenues.

I think the most amazing evening skies I ever saw with any regularity were when I was traveling in the Caribbean. The night sky doesn't get any more spectacular or encompassing than when you're looking at it from the open water on a boat with a busted mast light.

Lunar-resonant streetlights

But perhaps there's hope on the horizon, instead of more tungsten glow. An article I came across points to a design company in San Francisco who won a $10,000 prize for their "innovative, energy-saving urban outdoor lighting concept". The design collective asks, "What if streetlights could respond to ambient moonlight, dimming and brightening each month as the moon cycles through its phases? On clear nights when the moon is full, streetlights might even turn off completely."

The concept, which they call "lunar-resonant streetlights," has an overarching goal of reducing energy consumption and bringing back the experience of moonlight to urban areas. Existing streetlights would be retrofitted with high-efficiency dimmable white LED clusters (replacing the standard sodium bulbs), and complimented with sensitive photocells that can detect ambient light levels and electronically adjust the light output.

Lunar-resonant San Francisco

Naturally, replacing the millions of mercury/sodium vapor streetlights in the U.S. is a cost-prohibitive maneuver that is unlikely to be approved anytime soon, but I'd love to see white LEDs become the standard for streetlights the world over. Sadly, this proposal won't get our dark skies back (moonlight or streetlight will still be a constant), but I think such a thing will ultimately result in a positive physiologically impact on city-dwellers, and energy savings on a widespread level.

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