The Light Fantastic

Streetlights are about to change the color of night—for the better.

By Hal Espen
Mario Anzuoni/Reuters/Corbis

I detest sodium-vapor streetlights, whose yellowish glow now colors the night and stains metropolitan horizons everywhere. When I was growing up in suburban California in the 1960s and ’70s, the world after dark was lit by warm incandescence and whitish mercury-vapor street light. Although the latter had a spectral signature with vampiric overtones, turning reds to black and casting a blood-drained pallor on white skin, it still approximated something akin to plain white light.

But after the energy shocks of the 1970s, high-pressure sodium lights gradually took over the night. Following the economic imperative to use the most cost-effective lighting—high-pressure sodium lights consume half as much energy as mercury-vapor lamps and can last up to 16,000 hours longer—transportation departments and cities embraced sodium light. It was as though someone said “Fiat lux sulfurea—“Let there be light from hell.” The relentless spread of sodium streetlights is documented in NASA night photographs from space: New York City and Los Angeles are circuit boards of glowing orange, and Long Beach, one of the world’s busiest ports, is a flare of tarnished gold. It’s even worse in the United Kingdom, where 85 percent of streetlights use sodium. The jaundiced weirdness of sodium light has become a vexing challenge to photographers (one filmmaker, Tenolian Bell, called it “the ugliest light known to the cinematographer”); movie cameras simulate its color by using a gel filter named Bastard Amber. Significantly, retailers have avoided inflicting the unpleasantness of sodium lights on their customers—most commercial parking lots and shopping malls use the costlier white metal halide lights.

Our forced acceptance of sodium light’s ghoulish tint, an accident caused by the electrical vaporization of sodium metal in a gas-filled tube, makes outdoor lighting an example of a “bossy technology,” to borrow a term from Kevin Kelly’s recent book, What Technology Wants. Even worse than this inherent bossiness is the larger problem of light pollution. “Mankind is proceeding to envelop itself in a luminous fog,” wrote the authors of a paper on artificial night-sky brightness in 2001. This “perennial moonlight” that we’ve created enhances our safety and security, but it also dims our view of 10,000 stars and destroys the dance of light and dark.

But now we have a chance to bid good riddance to sodium vapor, and perhaps even resist the heedless trend of adding more and more light. The color of night is changing again.

In the next decade, a large percentage of America’s 37 million streetlights will be equipped with light-emitting diodes, or LEDs, and other kinds of solid-state lighting. Once again, energy-saving is the driving force. “We’re still at the front end of the wave,” says Mark S. Rea, the director of the Lighting Research Center at Rensselaer Polytechnic Institute, “but LEDs are inevitable as a replacement technology.” He predicts that LEDs, which are already 10 to 20 percent more energy-efficient than high-pressure sodium lights, will have a 40 percent advantage within a year or two.

Large-scale streetlight-upgrade programs have already begun in New York, Anchorage, San Jose, Pittsburgh, and many other cities. In Los Angeles, a $57 million project backed by the city’s Department of Water and Power and the Clinton Climate Initiative will replace 140,000 of the city’s 209,000 streetlights. Michael Siminovitch, the director of the California Lighting Technology Center at UC Davis, argues that the true potential and savings of the new lighting are less a matter of the source than of digital “adaptive controls.” Unlike sodium lights, LEDs and other next-generation lights can be tuned to various colors, easily dimmed, arranged into luminous surfaces and shapes, and turned on and off instantly.

Will this versatility translate into self-restraint? “We have the technology to make beautiful, modest night lighting,” says Jane Brox, the author of Brilliant: The Evolution of Artificial Light. “But our relationship to light is not rational. To ask people to live with less light, even if it’s well designed—a lot of people feel like that’s going backward.”

We’ve learned to be that neighbor who leaves a yellow porch light glaring all night long. Perhaps we can now learn, in the words of the lighting designer Rogier van der Heide, “why light needs darkness.”

This article available online at:

http://www.theatlantic.com/magazine/archive/2011/07/the-light-fantastic/308545/