The ecological impact of artificial light at night in landscape architecture : strategies and guidelines for street lights for the benefit of biodiversity and local wildlife

Sammanfattning: Artificial light at night (ALAN) is an increasingly common form of light pollution that contributes to biodiversity loss, loss of dark habitats, disrupting populations both on an individual- and population level by invading biodiversity hot spots. Recent studies show that artificial light is increasing at a rate of approximately 6% annually over Earth’s surface, and 88% of Europe and 47% of the United States experience light pollution on a nightly basis. Although the primary function of artificial light is to enhance safety, security, aesthetics, and navigation, ecological disruption is often a resulting effect post-design. Despite its prevalence and ecological impact, there has been little research on avoiding light pollution in landscape architecture. This thesis presents precautionary methods and practices for landscape architects and other actors, to mitigate and avoid light pollution specifically integrating into areas and habitats where biodiversity is at risk. In this thesis, various strategies and adaptations are used while utilising the Swedish legislation as a foundation and framework. In the context of the construction process (byggprocessen), landscape architects play a crucial role in the design department. However, they may face certain limitations when it comes to the construction of street lights. To create guidelines, it is important to identify and focus on the variables that landscape architects can take into consideration, manage, and design in relation to street lights. This thesis identified these variables as placement of street lights, type of light, colour, shielding, scheduling, appropriate light illuminance, and consideration of façade lighting. By utilising strategies and guidelines, landscape architects and other professions can introduce a more informed and intentional design. The strategies and guidelines can help to reduce the negative impact of artificial light on biodiversity and local wildlife. This thesis offers important insights into the urgent need for effective solutions to address the growing problem of light pollution and provides guidance on how to achieve this in the context of landscape architecture.