You've probably walked home along a city park late at night, walked the dog at dawn on a cold winter morning or crossed a green area on your way to work long before the sun has risen.
These activities require light to orientate ourselves. And with the long Nordic winters, where daylight is limited, outdoor lighting is essential.
The question is, how much light is needed, and how can we minimize the use of electric light and the negative impact on skyglow and wildlife? The interdisciplinary research project NorDark has set out to explore these questions.
Ute Besenecker is leading the project which involves researchers from the Royal Institute of Technology (KTH), Swedish University of Agricultural Sciences (SLU), Lund and Stockholm University in Sweden, NTNU in Norway, and Aalto University in Finland. These researchers are collaborating to contribute to a more complete knowledge base for design directions and policies on urban lighting with a more-than-human awareness.
‘We know that there can be a number of concerns associated with lighting urban green areas, but there is no comprehensive guidance yet in the Nordic countries, which is why this research is important. This project brings together expertise from six different research fields to learn about the effect and possibilities to minimize unnecessary lighting in Nordic urban areas.”
Test sites in Ålesund and Uppsala
In the last decades, new lighting technologies have emerged. Older technologies had the disadvantage that light qualities such as brightness and spectrum (e.g., colour appearance) could not be easily adjusted. But now, LED illumination allows us to accommodate variations in lighting qualities based on time, usage or environmental conditions, and knowledge is needed to inform sustainable approaches. Lighting and control technologies provide cities with options that didn’t exist as recently as 10-15 years ago, explains Besenecker.
One example in Nordic winters is that “the moment there is snow, we need less electric light, because the white snow cover on the ground reflects the light and suddenly the whole area looks brighter. How could lighting respond more directly to the local needs and conditions? This is another question that we hope to address with research.”
With these possibilities in mind, the research team is testing lighting scenarios in two selected locations in two Nordic cities – Ålesund in Norway and Uppsala in Sweden. Both locations are urban residential areas located adjacent to a protected green zone. There are paths that residents use for recreation, commuting, and getting to and from local schools and kindergartens.
While data is still being collected and analyzed, “based on preliminary observations, we think that by designing lighting qualities carefully, less light can be used without compromising pedestrian usability in these green areas,” Besenecker says.
Lighting can both support and harm
When we light up our cities, it is first and foremost to be able to see where we are walking or cycling when it’s dark. Without light on the ground we cannot safely navigate, but we also need to have a sense of what is going on around us, and light on objects and walls both built and natural/planted, can facilitate that.
“This makes environmentally friendly implementation of lighting in green areas difficult. If we illuminate the paths and minimize lighting the surroundings to avoid impacting wildlife, the light-dark contrast can get too high to see left and right beyond the path, for example, something or someone in the bushes along the path,” she says and continues:
“When the path is illuminated while everything else is dark, it can feel like walking on a stage without knowing if there is an audience which can feel uncomfortable. But if we just slightly change the direction and spread of the light beam, we can get a better sense of what's going on around us. Combined with dimming and adjusting the light to lessen the contrast, this can support vision (visual adaptation), creating an effect almost like walking under a full moon.”
