When capital cities like Paris and Berlin resolved to switch off lighting for public buildings and landmarks in July 2022 in order to save energy in the context of the Russian invasion of Ukraine, the cities created a ripple effect throughout central Europe. Images of dark iconic landmarks swept through the media and allowed politicians a momentary act of environmental demonstration. However, designers have started to question the sustainability of this ad hoc step. Seen from a broader perspective the impression arises that this alleged radical action has been part of a rather media-savvy campaign with small effect in cities at night. Further steps are necessary to reassess urban lighting that may have a major impact on energy saving and sustainability.
Whilst dimming light in interior spaces has become ubiquitous to creating ambience and conserving energy, control systems for outdoor and street lighting seem to have fallen technologically behind. This has become apparent in Berlin for instance where the municipal council sent out numerous technicians to 200 sites to disconnect power, taking three to four weeks in total to complete the process. Ironically, the electricity bill generated for manually disconnecting power matched the equivalent annual electricity consumption used to illuminate these 200 buildings. Particularly, this approach reveals that in the past the government neglected to combine street lighting with smart control systems. Whilst local authorities do not have access to façade lighting of privately owned buildings, cities in Germany have avoided taking a step that would save considerably more energy at night: For insctance, more than 200,000 installed street lights in Berlin reveal that the highest energy consumption for public lighting is not derived from public buildings as one may expect but from street lighting.
Energy saving challenges and opportunities for street lighting
The absence of systems thinking with two unconnected types of lighting and regulation standards may explain why we need more effective strategies to reduce energy usage in public street lighting. Car headlight technology has advanced tremendously in the automobile sector over the years. From LED and laser technology to smart and adaptive headlights, self-dipping beams and anti-dazzle high-beams, the design targets focus on increasing safety on the road by identifying vertical surfaces with accentuation and reducing glare to oncoming motorists. In stark contrast, street lighting regulations require high uniformity on the horizontal street surface. Whilst the performance of car headlights has advanced immensely, street lighting regulations have scarcely considered the automotive advancement for saving energy. In addition, the recommendations for the high quantity of light do not appear to be well-founded in robust empirical evidence, remark Steve Fotios and Ronald Gibbons and suggest reconsidering recommended light levels. Further on, lobbyism from two independent industry groups may have contributed to the complexity of finding an integral solution.
Smart energy-saving approaches can be found in Norway where adaptive street lights turn down on low-traffic roads. Street lights with radar sensors have been installed for several kilomentres along a low-traffic road that start-up to full brightness when they detect oncoming cars, cyclists and pedestrians and dim down as soon as the roads are clear. The technology with dimmable LED lighting would also allow a gradual increase of brightness after sunset in order to avoid the usual full energy consumption directly after sunset. An astronomical clock considering the sun’s position and including a brightness sensor could even reduce the illumination level for clear sky periods, requiring even less energy after sunset compared to overcast days.
Urban lighting between culture, ecology and emotion
The recent urgent lighting discussions and the energy-saving initiatives of limiting lighting on buildings, monuments and advertising, have sometimes created a disparity between the public sector and the private sector which nevertheless organized events incorporating lighting like Christmas markets and light festivals revealing an economic and social imbalance. Although the events tried to save electricity, they provided a bright and colorful contrast to the dark public buildings.
For the last two decades, the Dark Sky movement has continuously aimed to reverse the negative impacts of light pollution by persuading the public and policy to minimise outdoor lighting for improving conditions for ecosystems, animal and plant physiology and astronomical research or simply bringing back star gazing. Yet, the action for less light at night has only now been significantly accelerated through the current energy crisis. The drastic reduction measures introduced last year have also revealed that the economic and ecological impact has been underestimated by policymakers up to now.
News media has developed its own dynamic storytelling and quickly linked less outdoor lighting with people feeling less safe. However, several studies examined the impact of light on safety, but the majority of these studies are methodically flawed, remarks the chronobiologist Annette Krop-Benesch. A few well designed studies like crime in England do not support the claim that more light automatically means more safety, explains the researcher. A more differentiated view is necessary to address the complex factors influencing our feeling of safety at night.
Awareness for culture and implementation of smart technology
The European political strategy to limit illuminating iconic cultural buildings can teach us several important lessons. The quick dualistic thinking in temporarily switching light on or off neglects the fact that there could be also useful compromises between culture and energy. The media-savvy images of dark landmarks have represented low hanging fruit hiding other areas for saving energy which require more political effort, but which would create a far greater impact. In this way, the current energy measures appear comparable to the crisis management during the corona pandemic, where cultural and creative sectors did not have access to a strong lobby compared to other industries. Consequentially, the cultural landmarks vanished first by remaining dark. In general, street lighting needs to be rethought: Individual interests between the tender process owner, the installer, and the manufacturer need to be aligned to master complex and lengthy planning processes in order to implement smart technology faster. Regions not facing an intense energy crisis, like Europe at the moment, should remain alert by being conscious of available alternatives to completely immersing landmarks in darkness. After transitioning to efficient LED technology, the next biggest possibilty to save energy is control technology for smart street lighting which has a big lever arm to achieve sustainability goals set by the United Nations Organization fast. The challenge will be to balance the need for light and the need for energy reduction as well as ecology in order to find the right iterative steps towards a sustainable solution for our nights.
Light matters, a column on light and space, is written by Dr. Thomas Schielke. Based in Germany, he is fascinated by architectural lighting and works as an editor for the lighting company ERCO. He has published numerous articles and co-authored the books “Light Perspectives” and “SuperLux”. For more information check www.erco.com, www.arclighting.de.
