Updates to outdoor lighting rules mulled

At the December 7 State of the Town meeting, the Dark Skies Committee will give an update on its work to update rules on outdoor lighting to reflect changes in technology since they were last amended in 2016.

Artificial light at night keeps away wildlife (thus reducing their habitat), kills insects, and interferes with nocturnal breeding cycles and bird migration, said Louise Bergeron, head of the Planning Board subcommittee, in a presentation at the November 18 Select Board meeting.

Current zoning rules require permanent lighting to be installed or shielded to “prevent direct light or glare from the light source from interfering with the vision of motorists or pedestrians” or illuminating neighboring properties, and exterior lamps to have a color temperature of 3,000K or below. Lights must also be no more than 900 lumens (a measure of brightness). Color temperature refers to the color of the light — the lower the temperature, the more orange it appears, whereas higher-temperature numbers indicate bluer light.

Outdoor lighting was the topic of heated debate at Town Meeting in 2015, when voters rejected some rule changes.

In recent years, LED lights — which tend to have a cooler color temperature than incandescent lights — have become commonplace, and people are often tempted to buy the brightest outdoor lights they can, Bergeron said. Her group is also studying ideas such as allowing only activated lights in certain circumstances, and asking or requiring owners of larger buildings to turn off outdoor lights that currently shine all night, such as those in parking lots, schools, churches, and the Water Department.

Town officials can grant exceptions if warranted, and the public safety will continue to be exempt.

“This is a lot about education,” Select Board member Jennifer Glass said. “You’re going to get the best result when you educate people, because we don’t have the capacity to go around policing everyone.”