Dark-Sky Friendly Lights on Campus

Tuesday, February 16, 2016

Dark-Sky Friendly Lights on Campus Save Money and the Environment

by Rhy Doucette '10 and Rowen Webb-Forgus '10

For most of human history, thousands of stars shone in the night sky and the Milky Way galaxy was visible from anywhere on Earth. This spectacular view excited curiosity and inspired storytellers, artists, philosophers and scientists. Urbanization, however, has been accompanied by lighting that overpowers the nighttime sky. This brightening of the sky at night—known as light pollution—is caused by excessive and inefficient outdoor lights that direct light energy in all directions, including up into the sky. 

While at first light pollution concerned mostly astronomers, due to the loss of observing sites, recent research conducted by the International Dark-Sky Association (IDA) has shown that the light pollution affects everyone. Light pollution disrupts the circadian rhythm for both animals and humans. Lighting can confuse nocturnal animals’ hunting, migration and mating habits, and it can lead to headaches, sleep disorders, obesity, stress, and depression in humans, according the IDA. The IDA has also found that unshielded lights, with no measures taken to reduce light pollution, can also waste up to 30 percent of the energy used, pumping carbon dioxide into the atmosphere and costing billions of dollars worldwide.

In order to mitigate the effects of light pollution, the Illuminating Engineering Society (IES) and the IDA worked together to create the BUG system. This system provides a way to classify and identify light coming from street lamps and other lights into three categories: backlight, uplight, and glare (the words forming the BUG acronym). Backlight is light that shines from the back of the lamp and creates light trespass or light falling where it is not needed; uplight is light that shines above the lamp and causes sky glow and inhibits proper sky viewing; and finally, glare is light that comes out in such a way that it becomes visibly disabling or irritating. Categorizing these different types of light pollution provides a starting point to begin fixing the problem. Rating each light from a low pollution level (1) to a high pollution level (3), the IES and the IDA work with policymakers and the public to end light pollution.

Here on Agnes Scott’s campus (around the Woodruff Athletic Building and on the path leading to the Bradley Observatory), there are streetlights rated 1 in every category. A rating of 1 means that a light’s uplight, backlight, and glare are very minimal, and this not only creates a good local environment for stargazing but also helps the surrounding environment. Another important bonus is the decrease in energy use, and a consequent savings in money spent on energy.

On the Bradley Observatory’s pathway are 18 bollard lights; these are short, rounded lights installed in the year 2000 that give off an orange-colored light that protects people’s eyes and allows them to see the night sky more clearly. Near the track and the Woodruff Building are 11 gooseneck lights, which are tall, more traditional-looking streetlights with a shield surrounding the light bulb. The shield directs the light directly downwards, which prevents allowing the light from interfering with the surrounding environment or our view of the night sky.

Aaron McMeans, manager of technical services at Agnes Scott College, who researched these lights and supervised their installation, said, “We are saving a lot of energy. They are only using about half as much electricity as the old lights and with half as many poles. The total amount of energy used is down to about 25 percent of the previous level.”

With a beautiful dark sky around the Bradley Observatory and less energy use, these lights have done a lot for the Agnes Scott campus. Updating the streetlights provides significant economic, environmental and educational improvements for the college. Light pollution has been greatly reduced around the Bradley Observatory, creating not only better viewing conditions for astronomy classes but also healthier lighting conditions for the humans, animals and insects that live close by. The energy saved (which shrinks the campus’ carbon footprint) is another important benefit for the Agnes Scott community. Though these lights are only a small change, they represent a step towards reducing light pollution and preserving dark skies for generations to come.


Agnes Scott College educates women to think deeply, live honorably and engage the intellectual and social challenges of their times. Students are drawn to Agnes Scott by its excellent academic reputation, exceptional faculty and metropolitan Atlanta location—offering myriad social, cultural and experiential learning opportunities. This highly selective liberal arts college is known for its diverse and dynamic intellectual community. Through SUMMIT, it provides every student, regardless of major, with an individualized course of study and co-curricular experiences that develop leadership abilities and understanding of complex global dynamics.