Less light, smarter control, and more eco-friendly

The number of illuminated areas is increasing both in Europe and globally, and there are few places left today that are completely unaffected by electrical lighting and skyglow. 

In her research on sustainable urban development, Annika Jägerbrand, at the University of Gävle, north of Stockholm, is studying light pollution and its impact on species and ecosystems. She is an authority in the field both in Sweden and internationally, and her work involves standardisation that guides decision-makers regarding lighting in protected natural environments.

History repeats itself

At the beginning of the 20th century, the issue of increasingly illuminated cities was as topical as it is today. Annika shows a newspaper clip from the turn of the century when electric streetlights started to light up Stockholm.

    “Look here, they wanted it to be as ‘bright as the day’. Many of these subconscious ideas still permeate our thinking today, a hundred years later. Today we have 150,000 light sources in the city of Stockholm alone, and the number is increasing annually. As new areas and roads are built, the illuminated area usually increases, which means that more habitats and species can be adversely affected by light pollution.”

A big part of the problem is that there are no common guidelines or restrictions regarding optimal and appropriate light for both humans and animals.

    “For example, we do not have standards that prevent light across the horizon for light sources other than road lighting, which is regulated to some extent. It’s strange, because on the one hand it is a huge waste of energy, and on the other hand it creates skyglow and a lot of light pollution. This is also evident in satellite images. There are general guidelines internationally, but they are infrequently used by decision-makers in Sweden.”

Issues relating to the ecological consequences of light pollution began to be studied in earnest in the early 20th century. However, the first studies were not based on evidence, but more on observations.

    “Since no measurable studies were done, it is difficult to publish and compare the results. Today, there are extensive effects on large groups such as insects, birds, and bats, but this is still not sufficiently addressed in terms of lighting and to prevent adverse effects.”

To make progress in this, clear thresholds and a greater understanding of how different species are affected by electric light in the dark are needed.

    “In the international discussions, the focus is usually on how light pollution affects astronomy rather than ecology. But the measures required are not exactly the same. Astronomers focus on upward light pollution and on using lower colour temperatures. In ecology, it is more important to have no light at all - especially in sensitive environments - and to combine various measures to reduce the overall impact. We are not there yet.”

Control with third-party data

Technologies exist today that support the reduced use of electrical light, and with control based on third-party data, ecologically sensitive periods can be avoided. Lighting can be adapted to hatching periods and when migratory birds are active or governed by temperature. For example, insects are not active all the time, and very little when the temperature is below ten degrees.

     “There is presently a lot of information that can be utilised if you want to avoid disturbing specific groups. All lighting is designed for humans, and we need to change our expectations that outdoor environments must always be fully lit at all hours of the day and night - we must learn to compromise. Many people are also disturbed by light spill in their bedrooms, so ensuring more considerate lighting design offers several benefits.”

But lighting is a contentious issue. While residents typically want more lighting and brighter outdoor environments, such as around houses or along pedestrian and bicycle paths, ecologists want to conserve protected species and nature.

     “Ecologists think about how to preserve habitats in natural darkness. More research is therefore needed to find a good balance and more eco-friendly lighting for animals and nature,” concludes Annika Jägerbrand.

This article is part one of three in our article series about "Bioinclusive Lighting" - Lighting solutions that meet people’s need for light, in balance with the ecosystem. In the next article, we meet researcher Maria Nilsson Tengelin from RISE, who talks about a field study that Fagerhult participated in.