December 1, 2008
A Bright Future?
Cities are turning to LEDs as a way to cut costs—even before the technology has proven itself.
Michael Bergren turned to LEDs in a moment of desperation. Faced with a 6 percent spending cut, the assistant field-operations manager for the city of Ann Arbor, Michigan, had a choice: trim his fixed budget—which covers the cost of lighting public infrastructure—or get creative. He chose the latter. And so in 2006, Bergren wangled $10,000 to mount LEDs atop 25 light poles along restaurant-studded East Washington Street. This being Ann Arbor, the city put up friendly signs that read, “LED test light. Please let us know your feelings.” And—this being Ann Arbor—just about everybody loved them. “[T]he LED lights are very pretty with their jewel-like effect,” one couple wrote in, “You have our vote.” Two years later, some 600 new fixtures glow cold-white over downtown, with fewer than 500 left to convert. The estimated savings on energy, according to Bergren, are $14 a streetlight, or about $14,600 per year. There’s just one problem: the city hasn’t seen a dime of it.
Ann Arbor, like many municipalities, pays its local energy company, Detroit Edison, a flat rate to power and maintain public streetlights. The fee, locked into a long-term contract, is based on how existing lamps perform. But as LED technology makes energy consumption plummet, Detroit Edison isn’t eager to drop its rates in kind. “We don’t hope for a whole lot from them,” says Ann Arbor’s mayor, John Hieftje. “But we’re willing to move forward on our own.”
You’d expect that kind of progressive sentiment from the city that gave us teach-ins and Students for a Democratic Society. And yet Ann Arbor is hardly alone. LEDs have emerged as the knights-errant of municipal lighting, rising in Raleigh, North Carolina, parking garages; cutting through ebony skies in Anchorage, Alaska; and illuminating Haitian villages so deep in the hinterlands that a four-by-four chugging along at 20 miles an hour is required to reach them. In the United States, about two dozen cities have tested or plan to test LEDs, according to Bruce Kinzey, of the Pacific Northwest National Laboratory, a branch of the Department of Energy that has conducted extensive research on LEDs. These local governments are motivated by, in loose order: cost savings (and they do save over time, power bill notwithstanding), environmental responsibility, and design and aesthetic advantages. It is not uncommon for an elected official to hold forth on LEDs’ assorted capabilities. “We can put them on dimmers,” Mayor Hieftje says excitedly. “Or say a call comes into a 911 operator—we can make the streetlights flash so [emergency responders] have a beacon.” And so as the economy falls to its knees, a handful of American cities are more determined than ever to retrofit their streetlights. LEDs, the thinking goes, will change how we consume energy, how we invest in municipal infrastructure, how we design public space, and how we see at night.
Not that LEDs are new to the civic realm. Actually, tucked into traffic signals and crosswalk signs, they’ve spent the better part of a decade preventing cars from crashing into pedestrians. Illuminating city streets, though, has proved more trying. Until a few years ago, LEDs simply weren’t bright enough to meet minimum safety requirements, and early demonstrations in Honolulu and San Diego failed. But technology has made tremendous leaps since then. In 2006 the LEDs along East Washington Street were, at just 60 lumens per watt, considered the brightest on the market. Today, Cree, an LED manufacturer in Durham, North Carolina, sells a fixture that is nearly twice as strong, and is expected to slash energy use by 50 percent and to last nearly two decades with minimal care. (Traditional high-pressure sodium cobra heads, those tangerine explosions we’ve come to know and loathe, might need changing every three to five years.) LEDs are still more expensive upfront, but as some cities have calculated, costs can be recouped in about five years through maintenance savings alone.
There are qualitative benefits too. In Anchorage, where local officials are switching an ambitious 16,500 streetlights to LEDs, a group of residents was asked to compare the fixtures’ soft-white color temperature—similar to full moonlight—to the treacly glare of high-pressure sodium. Respondents overwhelmingly declared the white light brighter, more attractive, and safer-seeming, says Michael Barber, the city’s lighting-program manager and resource-efficiency specialist, even though the old lamps emitted twice as many lumens. There’s a science behind this. According to John Bullough, senior research scientist at Rensselaer Polytechnic Institute, certain photoreceptors in human eyes are more active after dark and allow us to see better in white light. This means that without a Sunkist haze mucking up night vision, a red car actually appears red, and a blue car blue. For Anchorage residents, who are accustomed to fewer than eight hours of sunlight a day, 85 days a year, such pure light is “a big deal,” Barber says. “It’s changing the way people experience more than half their day in Alaska. They’re actually seeing colors.”
In at least one city, LEDs are transforming more than just light quality; they’re changing the rules of design. In 2004 the Office for Visual Interaction (OVI) won a competition to revamp New York’s streetlamps, a terrifically mismatched stock—not unlike the city itself. The firm’s concept, a thin pole from which a line of LEDs extends in a faint arch, was entirely a product of the technology. Its compactness frees LEDs from bulky decorative envelopes (like globes and lanterns), but because the light source heats up, it needs ample surface area for cooling—hence the reedy curve. The design also focuses the LEDs downward, diffusing light over streets and sidewalks (and not blasting it into your window). “Instead of typical ‘hot spots’ under each light source, the LED streetlight will produce a more even distribution,” says Enrique Peiniger, a principal at OVI. In turn, the sleek design gives New York a sharper look; think Calvin Klein, not Dress Barn. “Overall, it’s a little more cleaned up,” says Jean Sundin, another OVI principal. “That’s always a good thing for New York.”
OVI plans to unveil six prototypes next year, but as the New York Times recently reported, it could be years before these lampposts permanently canopy the streets—if ever. The fact remains that LEDs in the public sphere are something of an underdog. The Department of Energy guesses it’ll be another five years before their up-front costs rival those of traditional streetlights. Even then, there’ll be a learning curve. “High-pressure sodium lamps have reasonably long life, and over time they do not get dimmer,” says Bullough, the scientist at Rensselaer. “Plus, they’re fairly inexpensive and widely available. You know what you’re getting when you install high-pressure sodium.” Which is why power companies, operating in a world where profit, not efficiency, reigns, aren’t especially keen to embrace the new technology. “When we make a decision about lights, it’s a permanent decision,” says Rick Larsen, director of market-and-energy services for Progress Energy, the company that buys, repairs, and powers Raleigh’s streetlights. “We’ve got to make sure they work.” (But perhaps things are looking up: at press time, Progress was installing nine LED fixtures in front of its headquarters, one of which will be tested for energy consumption.)
Raleigh can’t wait. The city grew so tired of the utility’s reticence that it struck out on its own, installing 28 LED lamps at a cost of $160,000—an investment it expects to earn back in addition to $100,000 saved on maintenance and energy over 20 years. “We don’t have the infrastructure to maintain [streetlights],” says Daniel Howe, the assistant city manager, “but we have confidence in the claims of the manufacturers. So we thought, OK, let’s make this investment and take a gamble that these aren’t going to be a maintenance hassle for us.” And so it is that outside a new 500,000-square-foot convention center on the cusp of downtown, the new lamps rise in bright testament to the city’s faith in innovation and sustainability. “It seems like every six or eight months the technology of the LEDs is taking another leap—they get brighter, the efficiency gets better, and the costs are coming down,” Howe says. “It’s looking better all the time.”