Vue nocturne du centre-ville de Douai éclairé par un éclairage public intelligent de LACROIX. ; Benefits of public lighting in Douai

Benefits of public lighting in Douai

Douai is a city of 40,000 inhabitants located in the north of France.
In 2021, the city launched a major project to renovate its public lighting network on the pedestrian and cyclist areas along the Scarpe river, called “Trame Sombre.”

The project in numbers:

  • 21 km of network
  • 16,000 inhabitants affected
  • 600 light points
  • 100% of the park in LED

Installed solutions

As part of the Trame Sombre project, the city of Douai installed the Tegis & SensyCity ecosystems:

  • The TEGIS remote management solution includes central management units (CMUs) installed in control cabinets, which allow for the reduction of nominal lighting power based on predefined hourly, daily, and seasonal scenarios.
  • The SensyCity detection solution includes motion sensors for pedestrians and cyclists (SIR). When the sensors detect movement, the Tegis communication nodes transmit the information to the LED drivers located at the base of the streetlights to adjust the lighting in real time.

Measurement of energy savings and avoided GHG emissions

Significant financial savings achieved through LACROIX’s intelligent management solutions:
For a project similar to the Trame Sombre in the city of Douai, we calculated a potential gain of €180,000 over 15 years from intelligent management compared to a LED park with nominal power lighting throughout the night.

Over the entire lifecycle, the net impact of the intelligent public lighting management solutions is very positive: the measured environmental benefits are between 4.7 times (GHG emissions) and 13.0 times (energy) greater than their footprint.

Installation and maintenance account for 20% of the footprint, which highlights the importance of selecting service providers (distance from the site, electric vs. thermal vehicles…).


Environmental sustainability being one of the major focuses of this project, we wanted to quantify the benefits brought by remote management in order to justify the relevance of our choices.

Roger COUILLET
Responsible for the outdoor electrical assets (City of Douai)


Access the study of smart lighting solutions in the city of Douai.

Benefits of public lighting in Douai