Street lighting dimming: strategies, technologies & implementation guide

• CMS, Smart urban lighting

Different street lighting dimming strategies and how to maximize their benefits

Quick summary

Street lighting dimming reduces luminaire output below maximum to save energy while maintaining required illumination levels. Four different dimming strategies serve different purposes in smart lighting deployments:

1. Time-based dimming follows fixed clock schedules
2. Sunrise/sunset dimming ties lighting to astronomically calculated sun times that adjust automatically throughout the year
3. Daylight sensor dimming responds to actual measured ambient light levels
4. Adaptive dimming creates a moving wave of light that travels with pedestrians, cyclists, and vehicles based on their speed and direction.

Three technologies implement dimming at the hardware level: 0-10V analog control (simple but limited), DALI digital protocol (bidirectional, diagnostics-capable, standards-based), and wireless control (flexible deployment, no additional wiring).

Why street lighting dimming matters beyond energy savings

Dimming is mentioned in virtually every smart lighting specification. But “dimming capability” covers a wide range of implementations: from basic on/off switching with a fixed dim level to sophisticated real-time adaptive control responding to sensor data across thousands of luminaires simultaneously.

Understanding what dimming actually involves—the strategies, technologies, and implementation requirements—enables to specify requirements correctly, verify vendor claims accurately, and deliver systems that perform as promised.

Furthermore, it’s important to understand that the primary motivation for street lighting dimming is energy reduction. But dimming serves several additional purposes that affect specification requirements:

• Light pollution reduction: excessive illumination during low-demand periods contributes to sky glow and ecological disruption. Dimming reduces unnecessary light emission, which is becoming increasingly relevant as European regulations on light pollution tighten.
• Infrastructure lifespan: LED luminaires operating at reduced output experience lower thermal stress. Dimmed operation extends component lifespan, thus reducing replacement frequency.
• Data generation: dimming generates data. A management platform tracking dimming across thousands of luminaires builds a detailed picture of system performance, energy consumption patterns, and operational anomalies, which is data that supports maintenance decisions and ROI reporting.

Dimming strategies explained

Strategy 1: time-based dimming

What it is: programmed dimming schedules that adjust output at predetermined clock times, reflecting typical usage patterns on each street or zone.

Example:

Flexibility: modern central management platforms support multiple independent schedules running simultaneously: different programs for main roads, residential streets, cycle paths, and commercial districts. Seasonal adjustments, public holiday programs, and special event overrides can be programmed in advance and activated automatically.

Best applications: predictable environments as a foundation layer within a broader adaptive system, thus providing the programmed baseline that adaptive control builds upon and improves based on real conditions.

Strategy 2: sunrise/sunset dimming

What it is: illumination schedules tied to actual sunrise and sunset times rather than fixed clock times. The central management platform calculates precise sunrise and sunset for the installation’s geographic location automatically, adjusting daily throughout the year.

Why it’s different from fixed time-based dimming: fixed time schedules (e.g., dim at 23:00) don’t account for seasonal variation in daylight hours. In Northern Europe, sunset varies by multiple hours between summer and winter. A fixed schedule either wastes energy (lights on before dark in summer) or compromises safety (lights still off after dark in winter).

Sunrise/sunset dimming solves this: the system knows exactly when the sun sets at that location on that date, and adjusts lighting accordingly: automatically, every single day, without manual reprogramming.

How it works: the central management platform contains astronomical calculations for the installation’s latitude and longitude. It computes sunrise and sunset times for each day of the year and triggers lighting transitions relative to those times. For example, reaching full output 30 minutes after actual sunset or beginning to reduce output 30 minutes before actual sunrise.

The key advantage: zero manual maintenance. Cities never adjust schedules seasonally. The system tracks the changing daylight hours automatically throughout the year, ensuring lighting always matches actual daylight conditions.

Best applications: all deployments benefit from sunrise/sunset intelligence as the schedule foundation. It’s a baseline that ensures lighting aligns with natural light availability regardless of season.

Strategy 3: daylight sensor dimming

What it is: illumination adjusted based on actual ambient light levels measured by a daylight sensor, rather than calculated sunrise/sunset times.

Why it improves on astronomical calculation: sunrise/sunset calculations tell you when the sun crosses the horizon, but not how bright it actually is at street level. Heavy cloud cover, fog, urban canyons (tall buildings blocking light), and tree canopy all affect actual illumination independent of the sun’s position.

A daylight sensor measures reality. On an overcast afternoon, ambient light may fall below safe levels while the sun is technically still up. The sensor detects this and activates lighting accordingly, which is something no astronomical calculation can do.

How it works: a photosensor measures ambient light levels continuously. When measured light falls below a configured threshold, the system activates or brightens luminaires. When natural light rises above the threshold, luminaires dim or switch off. The response reflects actual conditions at that specific location.

Best applications: locations where actual light levels diverge from astronomical calculations: shaded streets, areas with variable weather, urban canyons, and any environment where precise response to real conditions matters more than calculated times.

Strategy 4: adaptive dimming

What it is: real-time illumination that responds to movement. It creates a wave of light that travels with pedestrians, cyclists, and vehicles as they move through the street.

How Lusety’s adaptive dimming works: this is not the crude “walk under each light to activate it” approach that leaves people momentarily in darkness between luminaires. Motion sensors, luminaire controllers, and the central management platform work together to create genuinely intelligent adaptive lighting:

• Motion sensors detect a moving object and help to determine its speed and direction
• The system predicts where the object will be moments ahead
• Luminaires ahead of the object illuminate before the object reaches them
• The illuminated zone moves smoothly with the object *a wave of light traveling at the object’s pace)
• Luminaires behind the object return to baseline illumination

Configurable by distance: the illumination distance ahead of the moving object is configured in meters, not in numbers of luminaires. Cities set exactly how far ahead the light reaches, tuning the experience to local requirements and safety preferences.

Multiple objects tracked simultaneously: the system tracks every moving object independently. Two pedestrians walking in opposite directions each get their own moving zone of light.

Why this matters: the result is a street that’s fully lit exactly where and when people are present, and dimmed to minimum everywhere else. This maximizes energy savings while ensuring every person always travels within properly illuminated space. No dark gaps, no spotlight effect, no delay.

Best applications: residential streets, bicycle paths, pedestrian zones, and any area with variable occupancy where maximum energy savings and genuine adaptive response are both priorities.

Common question: should we specify one dimming strategy or combine multiple?

Combine them. The strategies work together as layers, not alternatives.

A well-configured system typically uses:

• Sunrise/sunset dimming as the intelligent schedule foundation (automatic seasonal adjustment)
• Daylight sensor dimming where actual light conditions diverge from astronomical calculations
• Adaptive dimming to respond to actual movement in real time
• Time-based overrides for specific requirements (events, specific zones)

Each layer operates within the parameters set by the others. Adaptive dimming responds to movement, but never dims below the minimum safety threshold defined for that zone. The management platform coordinates all layers simultaneously across the entire network.

Dimming technologies

How dimming is implemented at hardware level determines what strategies are achievable and what performance is possible.

0-10V analog control

How it works: a control signal between 0 and 10 volts is sent from the controller to the LED driver. 10V = full output, 0V = minimum output (typically 10%). Simple, proven technology.

Advantages:

• Low cost
• Simple wiring
• Compatible with legacy infrastructure
• Reliable in basic applications

Limitations:

• One-way communication only (controller sends commands, receives no feedback)
• No diagnostic data from luminaires
• No individual luminaire addressability (all luminaires on one circuit dim together)
• Limited to basic time-based or simple sensor-triggered control
• Doesn’t support advanced strategies without significant additional hardware

When it’s appropriate: simple installations where zone-level control is sufficient, budget is constrained, and advanced diagnostics are not required. Becoming less common in new European deployments as DALI has become cost-competitive.

DALI (Digital Addressable Lighting Interface)

How it works: digital protocol enabling bidirectional communication between controllers and individual LED drivers. Each DALI device has a unique address so controllers can command and query each luminaire independently.

Advantages:

• Bidirectional communication (controllers receive status, energy data, diagnostics)
• Individual luminaire addressability (up to 64 per DALI line, expandable)
• Detailed diagnostic data (lamp hours, driver temperature, fault codes)
• Supports all four dimming strategies
• DALI-2 standard integrates sensors directly
• Multi-vendor interoperability through standardized protocol

Limitations:

• Requires DALI-compatible drivers and controllers
• More complex installation than 0-10V
• Higher component cost than basic analog control

Why DALI dominates European deployments: DALI’s bidirectional communication enables the diagnostic and reporting capabilities that municipal procurement increasingly requires. Energy monitoring per luminaire, fault detection, and maintenance data are only possible with bidirectional protocols. DALI-2 certification ensures multi-vendor interoperability which is critical for projects with multiple manufacturers’ luminaires.

Wireless dimming control

How it works: dimming commands transmitted wirelessly from management platform to luminaire controllers, eliminating dedicated dimming control wiring. Controllers receive commands via LoRaWAN, NB-IoT, or mesh wireless networks and translate to appropriate driver signals (often DALI at the luminaire level).

Advantages:

• No additional control wiring required
• Flexible deployment and reconfiguration
• Suitable for retrofit projects (adding dimming to existing infrastructure)
• Enables remote parameter adjustment without site visits

Limitations:

• Wireless network reliability must be verified for the deployment environment
• Potential latency in command execution (milliseconds to seconds depending on network)
• Ongoing network costs (cellular-based technologies)

Best applications: retrofit projects adding smart capability to existing LED infrastructure, deployments where wiring additional control circuits is impractical, and large geographic areas where wireless infrastructure already exists.

Safety standards and dimming compliance

Street lighting dimming must comply with EN 13201, the European standard for road lighting. Compliance is non-negotiable in public procurement.

Key EN 13201 requirements relevant to dimming:

• Maintained illuminance: the standard specifies minimum average illuminance (lux) and uniformity ratios that must be maintained throughout the system’s operational life. Dimming systems must be configured to maintain these minimums at all times.
• Road lighting classes: different road types require different illuminance levels. A pedestrian path (P-class) has lower requirements than a main arterial road (M-class). Dimming minimums must be set appropriately for each road class in each zone.
• Dimming below standard: dimming below EN 13201 minimums is permissible under specific conditions defined in the standard: typically during very low-traffic periods with appropriate safety assessments. This requires documented justification and is not a default setting.
• Practical implementation: management platforms must allow zone-specific minimum brightness thresholds configured to the EN 13201 class of each road. Any dimming strategy—time-based, sunrise/sunset, daylight sensor, or adaptive—must respect these minimums automatically. Verifying this capability is essential during vendor evaluation.

How controllers implement dimming

• Cabinet controllers: manage dimming for groups of luminaires from central locations. Suitable for zone-level strategies where individual luminaire control is not required. Most cost-effective for large uniform areas.
• Luminaire controllers: implement dimming at individual luminaire level. Enable individual control, sensor integration, and the coordinated response that adaptive lighting requires. Required for adaptive dimming.
• Edge intelligence: both controller types should include local processing enabling autonomous dimming execution during connectivity loss. Pre-programmed schedules execute regardless of platform availability, thus ensuring streets don’t fail to dim (wasting energy) or fail to restore (creating safety issues) during network outages.

How central management platforms orchestrate dimming

The management platform, such as HORIZON, is where dimming strategies are defined, scheduled, monitored, and optimized.

Core dimming management capabilities:

• Schedule configuration: dimming programs with multiple time slots and seasonal adjustments. Programs should be configurable without on-site visits. Remote parameter adjustment is a baseline requirement.
• Threshold management: minimum and maximum brightness limits configurable per road class and local requirements. The platform must enforce these limits regardless of which dimming strategy is active.
• Override management: manual overrides for emergencies or maintenance with an automatic restoration to programmed schedules after defined periods. Override logging for audit purposes.
• Dimming state monitoring: real-time visibility of actual dimming levels across the network. Discrepancies between commanded and actual levels indicate controller or luminaire issues, generating maintenance alerts automatically.
• Energy reporting: dimming state correlated with energy consumption data enables savings reporting.

Platforms like HORIZON provide these capabilities through a centralized interface, enabling operators to manage dimming strategies across thousands of luminaires from a single dashboard, with each zone independently configured and continuously monitored.

Conclusions

Street lighting dimming encompasses far more than switching luminaires to a lower output. Understanding the four strategies, three implementation technologies, safety compliance requirements, and common pitfalls enables to specify requirements correctly, evaluate vendor claims accurately, and deliver systems that perform as promised throughout their operational lifespan.

Key takeaways:

• Four dimming strategies serve distinct purposes: time-based, sunrise/sunset, daylight sensor, and adaptive
• DALI dominates European deployments for good reason: bidirectional communication enables diagnostics, individual addressability, and advanced strategy implementation
• EN 13201 compliance is non-negotiable: minimum brightness thresholds must be configured per road class in every deployment zone
• Edge intelligence in controllers ensures dimming programs execute correctly during connectivity loss
• Central management platforms orchestrate all dimming strategies simultaneously: remote configuration, real-time monitoring, and energy reporting

Learn more

Do you have questions about street lighting dimming specification or implementation? We’re happy to share our technical experience with dimming strategy deployment across Europe.

Email us: info@lusety.com
Call us: +370 649 912 22

Note: this guide provides technical overview of street lighting dimming for educational purposes. For specific product capabilities and EN 13201 compliance requirements, consult manufacturer documentation and applicable national standards implementations.