This story was originally published in Public Works.
When the light-emitting diode (LED) became a streetlighting option, Bob Parks looked forward to gentler nighttime living in our cities and on our highways. He directs the nonprofit Smart Outdoor Lighting Alliance, which evaluates the technology’s real-world effectiveness (great case studies; I particularly recommend the one on Cambridge, Mass.). He used to be with the International Dark Sky Alliance, a nonprofit dedicated to reducing overlighting’s negative impacts on people and animals. He figured municipalities would heave a collective sigh of relief, confident that public rights of way would be lit for fewer taxpayer dollars. Instead, light pollution is increasing 3 percent to 5 percent every year.
The average city could increase visibility with half the illumination levels most use and spend a lot less in the process. Instead, cities that upgraded to LED are paying the same electricity bills to get much, much more light than they need.
This is partly because there are two sets of standards—one for intersections (Illuminating Engineering Society RP-8-14) and another for streets (Federal Highway Administration HRT-14-050)—and both emphasize uniformity and luminance instead of contrast, which is what our brain uses to interpret what our eyes send it. Constant lumen output (CLO), Parks says, should be the goal.
Another barrier to adoption, which LED suppliers should have known, is electric utilities have no incentive to make less money. Cities are saving less than expected because utilities increase tariffs to recoup revenues lost to energy-efficiency upgrades. The only way to change the power dynamic (no pun intended) is for the federal government to get involved (like it has with connected and autonomous vehicles), which isn’t going to happen. Each state legislature will have to force each state utility commission to change, and only California has succeeded.
And, finally, there’s the nebulous, intangible, unquantifiable but oh-so-potentially-painful public response to a change that appears to produce less light. Research shows that overlighting may actually increase crime, but who wants to put their job on the line by testing those results in the real world? That's a big risk for a public servant to take.
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