But a collective dimming of the lights won’t happen without municipal lighting ordinances, which work to make sure light is directed only where it is needed. Most towns have no regulations regarding how light is wasted, or the how the sky is illuminated. But a few are taking action, such as Flagstaff, Arizona, and Borrego Springs, California, two communities that have earned accolades from the International Dark-Sky Association (IDA) for their visibly darkened skies, the result of strong, enforced lighting ordinances.
Debra Briggs Norvil of Homer Glen, Illinois, used to be able to see the Milky Way from her backyard, but she says that’s changed in the last 25 years due to increased population and sky glow. Thanks to a 2007 local lighting ordinance, however, she may yet be able to do some serious stargazing again. In drafting the town ordinance in 2007, Norvil referenced the U.S. Pattern Outdoor Lighting Code, written by Chris Luginbuhl of the U.S. Naval Observatory’s Flagstaff station. Homer Glen’s code allows full cut-off outdoor lighting—meaning light is directed downward—for fixtures above 1,100 lumens and limits light trespass to 0.1-foot candles over property lines. A full moon high in the sky doesn’t exceed 0.05-foot candles, explains Norvil, “so a 0.1-foot candle is more than double a full moon’s brightness.” Code applies to new lighting, and a sunset clause requires all lighting to be up to code by 2018. The densely populated suburb of Eatontown, New Jersey, adopted its first lighting ordinance in 1993 for all new lighting installed; A revision in 2001 includes existing lighting. Eatontown’s rules emphasize uniform lighting, shielded light fixtures and limiting light trespass.
People tend to support overly bright streetlamps and other outdoor lights for safety reasons. “People believe that more light is better,” says Johanna Duffek, IDA spokesperson. “They’ll be able to see better and not be mugged and all those things they think light does. We understand that people want to be safe. We’re not anti-light, but [we are] pro quality lighting.”
The best ordinances require lights to be fully shielded and full cut-off—meaning no light is directed above the 90-degree angle (or horizontal plane) of the fixture. Light can travel up to 200 kilometers horizontally, so ultra-powerful lights can do damage when not aimed correctly. “When you’re focusing light on the ground, you can use a lesser wattage fixture that will give you a better-lit area, eliminates sideways glare and saves money over time,” Duffek says.
And advanced technology helps: Dimmers and motion sensors make smart lighting easier than in past. “It’s about directing the light where you need it and using light more wisely,” says Duffek.
Many ordinances or codes, such as Homer Glen’s, fall short on the enforcement end—they’re not regulated unless there’s a complaint from a neighbor. Instead, Duffek says, violators should get a warning, and then a ticket. Municipalities are much more focused on enforcing noise pollution—which has more research behind it, and is more easily measured—than light pollution, Duffek says. While we know what decibel levels damage our eardrums, there is not similar research citing what lumen levels cause sleep disturbances and other problems.
That makes writing lighting laws a tricky business. For instance, brightness is often determined by the surface that the light falls on: Asphalt surfaces reflect back less light than neutral-colored concrete.
Since Eatontown’s ordinance passed, John Batinsey of the town environmental committee has noticed a reduction in glaring lights. One big box store found that following the ordinance—including full cut-off lights with reduced wattages—saved about $45,000 a year in electricity costs, reports Batinsey—a win for the environment with all that reduction in energy use and related greenhouse gas emissions, and a windfall for the company.
Norvil reports a visible difference, illustrated by one new church in Homer Glen that uses full cut-off lighting: “You can definitely see how the light ends right at the property line,” she says.
CONTACT: International Dark-Sky Association.