Danish Town Pivots to Red Streetlights to Protect Bat Colonies
A pioneering initiative is underway in Gladsaxe, a municipality located just north-west of Copenhagen, Denmark, as it embarks on a significant shift in its urban lighting strategy. The town is replacing approximately 5,000 existing streetlights with new red light-emitting diode (LED) units, particularly along key thoroughfares like the tree-lined Frederiksborgvej. This strategic change is driven by a pressing need to mitigate the disruptive effects of artificial light pollution on a thriving colony of seven bat species that call the area home.
The decision to transition from traditional white lighting to a red spectrum is grounded in research conducted by the Danish Road Directorate (DRD). Their findings indicate that bats are particularly sensitive to short-wavelength light, including white, blue, and green hues. This type of illumination can interfere with their natural behaviours, such as echolocation – the process they use to navigate and hunt – as well as their breeding and feeding patterns.
By adopting red LEDs, Gladsaxe is introducing longer-wavelength light, which the DRD asserts has a considerably lower impact on the bats’ ability to utilise echolocation. This shift is also expected to reduce disruptions to their crucial breeding and feeding activities. Importantly, the red LEDs are designed to provide adequate illumination for road user safety, ensuring that visibility remains sufficient for drivers and pedestrians. Furthermore, these new lights offer several practical advantages: they consume less energy compared to older sodium vapour lights and require less frequent maintenance, presenting a more sustainable and cost-effective solution for the town.
Beyond their environmental benefits for local wildlife, the red streetlights are intended to serve as a visual cue for residents and commuters. The distinctive red glow aims to remind people that they are entering areas where vulnerable species reside and navigate, thereby fostering greater public awareness and encouraging more considerate behaviour towards the local ecosystem.
This ambitious project in Gladsaxe is partially funded by the European Union’s ‘Lighting Metropolis – Green Mobility’ program. This broader initiative extends across various cities in Denmark and neighbouring Sweden, with a collective goal of replacing around 50,000 older streetlights with energy-efficient LEDs.
In contrast, street lighting across Australia predominantly relies on white LED technology, which has largely supplanted older, yellowish sodium lights as infrastructure is updated. However, there are emerging efforts to address light pollution. For instance, trials are being conducted on Victoria’s Bass Coast, where warm-white LEDs are being implemented and can be dimmed to reduce their environmental footprint.
The widespread adoption of smart-enabled LEDs in Europe also signals a future where streetlights could become integral components of a connected urban landscape, potentially interacting with the software-defined vehicles (SDVs) of tomorrow.
Harry Verhaar, a spokesperson for the Dutch company Signify, outlined this vision in a 2021 report. He described streetlights evolving from mere sources of illumination to “digital nodes with their own IP address on a network that extends to every road and street in your city.”
The Evolving Role of Streetlights
The potential capabilities of these advanced streetlights are far-reaching:
- Connectivity Hubs: These lamps could host 5G and Wi-Fi connectivity, serving as vital communication points within the city’s digital infrastructure.
- Integrated Services: They may incorporate remote-controlled billboards, CCTV cameras for enhanced security, and microphones designed to detect sudden loud noises, which could then be swiftly investigated.
- Data Collection and Analysis: Equipped with nodes and sensors, these streetlights can gather valuable data. This information can provide insights into electricity usage patterns, noise pollution levels, and traffic flow.
- Adaptive Illumination: The brightness of the lights can be dynamically controlled, adjusting to the ambient activity in their vicinity, thereby optimising energy consumption and minimising unnecessary light spill.
The implications of such smart city infrastructure are significant, promising not only improved efficiency and sustainability but also enhanced safety and a more responsive urban environment. While Gladsaxe’s red lights focus on ecological preservation, the broader trend towards intelligent street lighting suggests a future where our urban infrastructure plays an increasingly sophisticated and multifaceted role in city life.
