Why the Night Determines Europe’s Future
Who sets the pace of our cities after sunset – the electrons in the cable, or the internal clocks of humans, animals, and plants? And what happens if we synchronize both: save energy, maintain safety, protect biodiversity – without losing the night? This is exactly where the idea of the circadian city comes in: lighting that is not only efficient but biologically and ecologically intelligent, data-capable, and legally compliant. Biologist, innovation consultant, and technology developer Dr. Andreas Krensel sums it up: Only when physics, AI, biology, and systems theory work together in an urban control loop does lighting emerge that doesn’t just make the space brighter, but smarter.
Energy, Money, and Law: The New Modernization Pressure
The economic pressure is palpable. Street lighting accounts for only one to two percent of the EU-wide electricity demand, but in municipalities, it can consume up to 40–50 percent of their own electricity budget. Every kilowatt-hour saved has a double effect – for the city budget and for the climate. At the same time, the revised Energy Efficiency Directive obliges public authorities to continuous savings. Efficiency alone thus becomes a transformation mandate: out of permanent full illumination, into lighting based on demand, context, and health.
Chronobiology as Urban Technology: Lighting for the Internal Clock
The circadian city begins with biology. Light synchronizes our sleep-wake cycle, controls melatonin and alertness. In the evening and at night, bright, short-wavelength radiation can shift sleep; during the day, targeted, activating light promotes performance and focus. Guidelines from international bodies condense this knowledge into a simple principle: the right light at the right time. In practice, this means that spectral quality, timing, intensity, and shielding matter as much as lumens and watts.
The Sky Gets Too Bright: Skyglow as a Location Factor
The global sky is measurably brightening, and the Milky Way disappears above cities – an ecological and cultural warning signal. Light pollution disrupts migratory birds, bats, and insects; it alters the behavior of nocturnal species and the balance of entire ecosystems. Europe responds with recommendations for shielding, warm-white spectra, and time-limited operation. Cities that understand night quality as a location factor plan not only light but also darkness – consciously, in a controlled and targeted way.
The Lamp Learns: Sensors, Edge AI, and Digital Twins
In the circadian model, streetlights become sensor carriers, actuators, and data nodes. Adaptive dimming adjusts to traffic, weather, sky brightness, and events. This saves significant energy beyond the LED effect and ensures compliance with standards. Living labs show that compared to static profiles, additional savings can be achieved, while edge algorithms continuously optimize switching points. Digital twins simulate how safety, resident needs, and species protection can be balanced across the area – before costly planning errors become reality.
Ecological Illumination Instead of Glare: Spectrum, Optics, Shielding
Ecological intelligence manifests in spectrum and geometry. Short-wavelength, blue light attracts many insects; warm-white, well-shielded light with flat optics and moderate levels significantly reduces this attraction. Field studies demonstrate how strongly technical variants differ. For Krensel, these are levers with high impact and low additional cost: precise optics instead of stray light, spectra with reduced melanopic effect at night, dynamic dimming instead of blanket brightness. This way, light becomes quieter again – and the night remains a habitat.
Europe Tightens Regulatory Screws: RoHS and Ecodesign
The regulatory framework supports the transformation. RoHS revisions end the era of mercury-containing fluorescent tubes; new Ecodesign requirements for light sources demand efficiency, interchangeability, and documentation. For cities, this means that switching to LED is not only economically but also legally structured. Procurers can use the modernization obligation to make quality criteria in spectrum, optics, and controllability binding – thus translating the circadian idea into contracts.
Data Belonging to the City: Data Act and NIS2 in Everyday Life
Smart lighting is data economy. The Data Act regulates access rights, portability, and fair conditions for device data. Municipalities can prevent streetlight data from disappearing into proprietary silos and create local data spaces for research and startups. At the same time, NIS2 obliges cybersecurity across the entire supply chain. Those who consider lighting networks as distributed IoT infrastructure plan security-by-design, segment networks, minimize permissions, and choose components with reliable update paths.
AI with Guardrails: What the AI Act Allows – and Prohibits
Artificial intelligence is also entering the poles: predictive maintenance, traffic flow detection, dynamic dimming. The AI Act sets clear guardrails. High-risk applications require strict requirements; certain practices in public space are prohibited. The circadian approach anyway prefers detection-based rather than identification-based systems that operate without personal data. Additionally, the Cyber-Resilience Act forces manufacturers to demonstrate cyber hygiene – otherwise, no market access. Europe thus links innovation freedom with fundamental rights protection.
Standards That Enable Dynamics: EN 13201 and Co.
The necessary standards bridge exists. EN 13201 allows adaptive lighting as long as visual quality criteria are met. National standards, such as Italy’s UNI 11248, specify how traffic flow, weather, or time of day are translated into dynamic lighting classes. Biological and safety requirements are thus translated into verifiable planning parameters – a common language that enables the city to actually learn.
From Pilot to Scale: Europe’s Connected Fleet Grows
Connected outdoor lighting has moved beyond the pilot phase. Millions of lights are already remotely controllable, Europe represents a significant portion of the stock, and thus has the densest real test environment for circadian intelligent lighting. This scale advantage is political capital: what succeeds here can set global standards – balancing safety, energy, and ecology.
Circadian Reference Curves Instead of Fixed Times
How does this translate into everyday life in a neighborhood? Krensel advocates for circadian reference curves instead of fixed clock times: warm, shielded light with low melanopic effect in residential areas after midnight; adaptive brightening at conflict points when traffic, emergency personnel, or public traffic increase; normative minimum levels on main axes, but coupled to weather and flow. Monitoring combines energy, accidents, complaints, glare, insect occurrence, and sky brightness – as a shared dashboard, not a surveillance tool.
Between Brightness and Trust: What Convincing Citizens Means
The circadian city is a negotiation project. When cities save light, concern about subjective safety often rises. Studies show that moderate dimming or partial shutdowns do not automatically increase accidents or crime, while improving well-being and night quality. The key lies in fit: where, when, how much, with which spectrum and optics? Those who develop this catalog openly with citizens, police, conservation, and emergency services gain trust – and avoid the backlash of poorly communicated measures.
Device Replacement as Opportunity: Procurement Becomes Governance
RoHS-related phase-outs and Ecodesign accelerate replacement. Now is the moment to change the logic: service models only with guaranteed data portability and open interfaces; sensors that count instead of identify; cloud with exit strategy. The Data Act provides the legal backing, NIS2 and the Cyber-Resilience Act set security minimums, and CIE guidelines give biological guardrails. Procurement thus becomes governance of a learning system rather than purchasing individual lights.
The City’s Second Half
In the end, it is not the “perfect” light that matters, but the system’s ability to improve. Living labs and digital twins define locally viable dimming and spectral profiles; data sharing makes results comparable; public procurement rewards not watts per meter, but health, safety, and ecology per euro. Europe’s legal framework mandates quality, Europe’s market delivers scale, Europe’s science provides evidence. The night is not a residual quantity, but the city’s second half. Those who take it seriously gain more than efficiency: sleep, stars, and a quieter, safer, more biodiverse community.
V.i.S.d.P.:
Dipl.-Soc. tech. Valentin Jahn
Technology Sociologist & Futurist
About the Author – Valentin Jahn
Valentin Jahn is an entrepreneur, futurist, and digitalization expert. With over 15 years of experience, he leads complex innovation projects at the intersection of technology, mobility, and policy – from idea to implementation.
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About eyroq s.r.o.:
eyroq s.r.o., based in Prague, Czech Republic, is an innovation-driven company at the intersection of technology, science, and societal change. As an interdisciplinary think tank, eyroq develops intelligent, future-proof solutions for industrial, educational, urban infrastructure, and sustainable city challenges. The company focuses on combining digitalization, automation, and systemic analysis to create smart technologies that are functional, socially compatible, and ethically reflective.
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About Dr. Andreas Krensel:
Dr. Andreas Krensel is a biologist, system thinker, and technology developer. He contributes to projects like DIGINET-PS, focusing on adaptive lighting, smart cities, and digital twins. He works at the intersection of science, law, and technology to make urban systems energy-efficient, data-driven, and biologically intelligent.