LED savings can come at cost to Bainbridge night skies

LED lighting benefits the environment by cutting electricity use substantially. But when lower operating costs encourage brighter fixtures, more lights, or longer hours, some savings are lost—and Bainbridge Island’s night skies suffer.

Researchers call this a rebound effect: cheaper light encourages greater use. Excess illumination can spill into neighboring homes and habitat, while light escaping upward or reflecting from pavement creates skyglow that washes out stars.

Color matters too. Lumens describe light output; color temperature, measured in kelvins (K), describes its appearance. Higher-temperature white LEDs generally contain more blue light, which contributes disproportionately to skyglow. DarkSky International recommends 2200K or amber outdoor lighting options where possible. A low purchase price says nothing about whether a fixture is suitably warm, shielded, or sized for the job.

DarkSky International warns that artificial light disrupts bird, mammal, marine life, and insect feeding, reproduction, and migration. The U.S. Fish and Wildlife Service says nighttime lighting can attract migrating birds, exhausting them and increasing collision risks. In a 2021 English study, researchers found 47 percent fewer moth caterpillars in illuminated hedgerows than in comparable unlit locations, with stronger effects under white LEDs than sodium lamps.

For Bainbridge’s wooded neighborhoods, wetlands, and shoreline habitats, those findings raise concerns about lighting beyond the pavement it serves. Insects pollinate plants and feed birds and bats. Darkness is part of that habitat.

Darkness also supports the Battle Point Astronomical Association’s Battle Point Observatory, where darker skies help reveal faint celestial objects. The association connects astronomy with conservation: an October 1 notice urged residents to dim or switch off unnecessary outdoor lights during bird migration.

Winslow has a growing number of these over-bright LEDs. Look no further than new parking-lot LEDs at the Congregational Church on Madison Avenue and the office complex behind 231 Winslow Way E. as appearing far brighter than their tasks require.

Despite limited Bainbridge code provisions, they prove inadequate to protect our environment and night skies. While Bainbridge already requires some outdoor lighting to be shielded, directed downward, and controlled to prevent light trespass, these requirements do not require DarkSky-certified fixtures, set a maximum color temperature, or set maximum brightness. Many “dark sky communities” have codes that specifically address these additional night sky protections.

More light does not automatically mean greater safety. A study covering 62 local authorities in England and Wales found evidence that reducing street lighting does not increase collisions or crime. Similarly, a 2000 Chicago study found no “conclusive evidence that increased alley lighting had an effect on crime.” Brighter does not automatically mean safer.

DarkSky and the Illuminating Engineering Society recommend lighting only where and when needed, using the lowest necessary level, shielding it carefully, and choosing warmer colors. Timers, dimmers, and motion sensors can preserve useful illumination while giving neighboring homes, wildlife, and the night sky a break. And the City code can be improved to better protect our environment and night skies.

If these things matter to you, write your City Council here.