The Five Principles of Responsible Outdoor Lighting Design

May 15, 2020: IDA and IES announce strategic collaboration to advance quality lighting to reduce light pollution

New York, NY, April 16, 2020. The International Dark-Sky Association (IDA) and the Illuminating Engineering Society (IES) announce a strategic collaboration to address the global issue of light pollution that negatively affects our environment and the human condition.

The Boards of Directors of IDA and IES have unanimously adopted Five Principles for Responsible Outdoor Lighting. By joining forces, IDA and IES seek to guide the outdoor lighting industry in the U.S. and beyond to be more socially and environmentally responsible.

“The Five Principles for Responsible Outdoor Lighting that unite our organizations are based on simple ideas; limit light at night to where and when it is needed, don’t overlight, and be sensitive to environmental concerns,” said Brian Liebel, Director of Standards and Research for the IES. “Following these Principles is not difficult and results in more effective and comfortable lighting installations.”

In recent years, light pollution has increased globally by two percent per year. The indiscriminate use of electric lighting at night leads to at least $3BN in wasted energy in the U.S. alone. This wasted light can harm wildlife, imperil important astronomical research, and can obscure our view of the star-filled sky.

“By following these simple principles, electric lighting at night can be beautiful, healthy, and functional. These principles work together to reduce light pollution, save energy and money, and minimize wildlife disruption,” said Ruskin Hartley, Executive Director of IDA.


Five principles for responsible outdoor lighting

USEFULAll light should have a clear purpose
Before installing or replacing a light, determine if light is needed. Consider how the use of light will impact the area, including wildlife and the environment. Consider using reflective paints or self-luminous markers for signs, curbs, and steps to reduce the need for permanently installed outdoor lighting.

TARGETED – Light should be directed only to where needed
Use shielding and careful aiming to target the direction of the light beam so that it points downward and does not spill beyond where it is needed.

LOW LIGHT LEVELS – Light should be no brighter than necessary
Use the lowest light level required. Be mindful of surface conditions as some surfaces may reflect more light into the sky than intended.

CONTROLLED – Light should be used only when it is useful
Use controls such as timers or motion detectors to ensure that light is available when it is needed, dimmed when possible, and turned off when not needed.

COLOR – Use warmer color lights where possible
Limit the amount of shorter wavelength (blue-violet) light to the least amount needed

About the International Dark-Sky Association: Our volunteer advocates work in 32 countries on six continents to protect the night from light pollution and celebrate the many benefits of a dark, star-filled sky. Learn more at

About the Illuminating Engineering Society: Established in 1906, the IES is the recognized technical and educational authority on illumination.

Posted in

Dave Drumel

Leave a Comment