This is a good news-bad news-good news story. The first good news: Seattle is leading the nation into a bright new future of energy-efficient, cost-saving LED street lighting; a future limned with truer colors, better visibility and, maybe, safer streets. The bad news: despite extensive, much-touted prior testing, the city has been installing these new streetlights in crude one-size-fits-all fashion, with little regard to Seattle’s hilly terrain and bombarding many residents, outside and sometimes inside their homes, with intrusive, blinding glare. The other good news: It can and will correct these problems — if you call to complain.
Seattle is with Los Angeles as a pioneer on the road to LED streetlights, which it began trying out clear back in 2007. Its efforts hit overdrive in 2009 when the Nickels administration secured a stimulus grant to start converting about 41,000 lights on residential streets to LEDs. Mayor McGinn upped the ante last June when he and LA’s Antonio Villaraigosa introduced a measure adopted by the U.S. Conference of Mayors urging that every city switch to LED streetlights — presumably with suitable federal funding. Edward Smalley, Seattle City Light’s chief streetlight engineer and a longtime LED booster, is the director of the U.S. Department of Energy’s Municipal Solid State Street Lighting Consortium — the point man for LED conversion nationwide.
The advantages of the new technology are manifold. LED displays use as little as 40 percent of the electricity that high-pressure sodium bulbs, the old standard, use to produce as much light. Though they cost more upfront, they last about three times as long, which saves labor replacing them and disposal costs. They don’t get jiggled to an early demise by vibration, as bulbs do, making them especially well-suited to bridges and other bouncy sites. City Light expects to recover the capital cost of converting in 7.7 years; it originally expected to save $2.2 million a year in energy and labor, but now hopes to save $3 million.
LEDs can deliver not only cheaper and more durable, but better quality and more versatile lighting. High-pressure sodium bulbs, with their pale-orange glow, operate at the warm end of the light spectrum, about 2,100 kelvins; incandescent and “soft white” fluorescent bulbs emit about 3,000 kelvins, and office fluorescents 3,500. (Cooler light is thought to be stimulating — bad for sleep, but good for work.) LEDs can be made with your color temperature of choice; the cooler the temperature (i.e., the bluer the light), the less energy they consume.
Seattle considered an icy 6,000 kelvins but opted for a merely chilly 5,000, the temperature of moonlight.
Many people find this cool light unsettling, at least at first, but it also makes for truer colors. Police like LEDs because they help witnesses accurately report whether a suspect drove a blue or green car or wore a black or brown hoody. Politicians like any excuse to proclaim that they’ve made the streets lighter, brighter and safer. Street lighting is like long, determinate prison sentences: More is always presumed to be better, and no politician ever lost an election calling for it.
But for many residents living under them, the new lights are a mixed bag. For some, they’re a nightmare. When the new lights arrived in Wallingford in late 2011 (the city installed them north of the Ship Canal first, and then started working up through the South End), the Wallyhood blog lit up with comments, from “a bit better than the yellowy light we used to have” to “HATE the color…HATE the sharp glare…HATE that it makes everything under it look cold and blue.”
For many the shock of the blue fades with familiarity. “I don’t hate them so much as I did at first,” says software engineer and light-pollution watchdog Bruce Weertman. “I actually like the white — it’s more natural.” The bigger problem, for Weertman, the Wallyhood bloggers, and your correspondent, is the new lights’ blinding glare and surprisingly intrusive reach.
“We can’t sit comfortably and read in our living room without the curtains drawn,” one Wallyhooder noted after the LEDs arrived. Worse yet, I could sit and read in my living room with the curtains open — by the glow of the streetlights. The streets outside (we’re on a corner lot) were lit up like a prison yard, and suspended mini-novas pierced the eye with glare when you stepped out to the sidewalk.
It’s not supposed to be that way. Another argument for LEDs is that they can be precisely targeted where light’s needed, rather than scattering and trespassing where it’s not. But these good intentions sometimes collide with the shakeout state of the industry (the technology’s always improving, and the city keeps seeking better makes), the nature of the technology and the hills and dales of a city like Seattle.
Rather than a single bulb, whose emission is reflected and directed by the backing fixture, an LED fixture has 120 little diodes —“like an array of small spotlights,” in the words of Ballard-based lighting engineer Dan Salinas — variously pointed to cast what’s supposed to be a composite block of even light.
From some angles the results are amazing: You can stand bathed in light and look straight up into one of the new streetlights without blinking. From others, they’re excruciating: Step back and that same fixture will glare like a headlight. (See photos.) “That’s because the peripheral lights are directed horizontally,” explains engineer and lighting maven Terrence McCosh, “and LED optics defeat the inverse square law” — which holds that the intensity of a property (in this case light) is inversely proportional to distance from its source.
Steep slopes complicate the angles and compound the effect. An LED fixture a block or two up a hill can glare brighter than one across the street.
Seattle City Light is swapping out the city's traditional streetlights lumen-for-lumen — replacing the old lights with LEDS rated at the same output. City Light spokesman Scott Thomsen says that’s at the direction of the Transportation Department and City Council, and in keeping with national standards for street lighting. But it’s also deceptive. “You really can’t judge lighting by its output,” says Salinas, who sits on the board of the national Illumination Engineering Society, the leading professional group. “You can’t say this amount of LED is going to replace this amount of high-pressure sodium. You have to consider the total system — do a photometric calculation so you can see how the light is distributed.”
Because their output isn’t lost to back-glow and dispersion, LEDs are effectively brighter than nominally equilavent traditional lights. City Light Thomsen acknowledges that there’s an emerging view in the field that “because of the higher quality of light [with LEDS], you can reduce lumen output,” and that the city may look at doing so in the future.
Right now, however, it’s switching the lights over lumen-for-lumen — effectively upsizing Seattle’s residential street lighting. They then tinker individual lights — reducing output or adding glare shield when residents complain and city engineers confirm a problem. “That’s not necessarily the best way, not the way I would do it,” says Salinas. “But they think it’s more efficient.”
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