At night, the Dutch town of Nieuwkoop is red. Fast Company's Adele Peters says that the neighborhood is next to a nature reserve home to threatened species of bats–and it’s the first in the world to install new bat-friendly street lights.

“Bats don’t see red light as particularly bright, if they see it at all,” says Maurice Donners, a senior scientist and innovation specialist at Signify, formerly known at Philips Lighting, which designed the new street lights. “So if you have certain bat species that are really avoiding light, we thought the obvious thing to do was take a portion of red light which is visible to us, but is much less visible, or perhaps even invisible, to bats.” Since bats are nocturnal, bright lights have an impact on them. The red lights solve the problem of disturbing light-avoidant bats, and also don’t attract bugs. There’s some evidence that they also may be better for other nocturnal species, like mice.

When the town of Nieuwkoop started planning to build 89 homes next to the nature reserve–one of a network of reserves across Europe that provide breeding and nesting sites for rare species–every aspect of the project had to consider the environment. “They got the building permits on the condition that they would do everything possible for the highest level of sustainability and especially not disturb the neighboring nature,” says Donners.

For humans, Donners says the lights perform as well as typical LEDs–the brightness meets the same requirements for rural neighborhoods, and human eyes quickly adapt to the color. “We have a mechanism in our visual system which is much like the automatic white balance in a modern camera, which will tell our brains actually the lighting which you see is white,” he says. “So it will adapt your perception. After a couple of minutes, you won’t notice anymore that it’s really red.”

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