Bat-friendly lighting in Gladsaxe
Gladsaxe Kommune is a municipality near Copenhagen in Denmark where Light Bureau is working to upgrade all the streetlights to LED along Frederiksborgvej near Skovbrynet.
Client : Gladsaxe Municipality
Completion year : 2022
Photographer : Rune Brandt Hermannsson
Light, Nature, and Humans - A Compromise
Reducing the amount of light in the area
This area is also home to several species of roosting and foraging bats. Specifically, along a 700m-stretch of Frederiksborgvej and the cycle superhighway ‘the Farum route’.
The brief for the project was to implement a lighting solution for the road and the bicycle path with the lowest possible impact on the living conditions for the bats in a nearby colony. Fortunately, Light Bureau had the privilege of working closely with the client, who was open to test out alternative solutions.
Based on scientific research on the biological impact of lighting on bats and their prey, alongside briefings from biologists, Light Bureau worked out a compromise between the needs for humans and bats and designed an innovative solution with the lowest possible environmental impact.
Research shows that red light is less disruptive on wildlife while allowing people to find their way and even maintaining their dark adaption for nighttime viewing, so a narrow bandwith of red light was chosen for the solution.
The lighting is projected from an installation of 30 bollards of 1 meter height spaced with a 30 meter distance. The bollards are placed far apart to create corridors of complete darkness, allowing for light-shy species that are earth-bound to cross the area without being exposed as potential prey and still providing ample lighting for the bicycle path.
The frequency in which the bollards are placed aims at reducing the amount of light in the area and only introduce what is necessary for cyclists to pass through the area. This way, we can preserve the nearby habitat of protected bats and secure a low impact on their natural behaviour as possible.
Where cyclists and pedestrians need to cross the road, 12 higher poles of 3.5 meter have been placed to create a change in the environment, which helps improve awareness and increase safety in these specific areas.
The red light has both functional value and symbolic value, making passers-by aware that this is a special natural area which the municipality wishes to protect and preserve.
“This is a new type of project for us and we had several discussions with biologists and bat experts, to establish how we could achieve the best compromise between fulfilling both human and bat needs. In the coming year want to establish more cooperation with the biologists, to evaluate if it has had the planned effect and learn from this case”
Site specific lighting
The red light may seem radically different from what people would normally expect from streetlighting. To pre-empt questions and citisism the municipality made an effort to explain the new light and its purpose through local media, and in discussions on social media. Emphasizing that this project is a part of Gladsaxe Municipality’s implementation of UN Sustainable Development Goals, with an aim to take the lead in ensuring the best conditions locally for both animals, humans and biodiversity.
This project will form the basis for future discussions of how we translate scientific research and technical knowledge into site specific lighting projects and how to design low-impact lighting solutions.
Lighting designer, DK