Rouhling. Renovation of public lighting: consumption down by 66.2%

Less than two and a half years will be enough for the municipality of Rouhling to recoup the cost of renovating its public lighting. The savings are significant from the first year of operation, with 55,647 kWh consumed in 2024, compared to 164,470 kWh in 2021, a decrease of 108,823 kWh (-66.2%), "while we already had 180 LED lamps," observes Jean-Luc Eberhart, the mayor. In 2023, when the municipality had turned off the lighting at night, it consumed more (71,912 kWh) "than with the lights on and dimmed."

Rouhling's public lighting system has eight power supply cabinets and 422 light points, 242 of which were still energy-intensive sodium vapor lamps. In 2022, soaring energy prices prompted the municipality to turn off public lighting from 11 p.m. to 5 a.m., from October 22, 2022 to January 5, 2024, while simultaneously launching a fixed-price contract for the replacement of luminaires. It had set several objectives to achieve: achieving a minimum efficiency of 160 lumens (Lm)/W, being able to control the lamp, and committing to energy savings. The entire system was affected, "even the LED lamps that we changed four or five years ago," explains Jean-Luc Eberhart. "They weren't controllable and were of low efficiency." For greater consistency, only three lamp models were desired at most .

Five companies responded. The bid from an Alsatian company was selected for €181,230 excluding VAT, 70.5% of which was financed by subsidies (€75,140 from the Green Fund, €30,000 from the Sarreguemines Confluences urban community, and €22,700 from energy savings certificates), and the remaining €53,390 excluding VAT from the municipality's own funds.

The work took place between September 2023 and April 2024. Three lamp models were selected, with a performance of 180 Lm/W, “each equipped with a communication module” offering the possibility of reducing or increasing the power.

For now, three programs have been defined. One to illuminate two intersections, another for the bowling alley, and the third for the entire town. Until 11 p.m., lighting is reduced by 50%. From 11 p.m. to 5 a.m., it is reduced by 80%, rising to 50% of the power from 5 a.m. until sunrise.

At intersections, the brightness remains at 50%. "We explained to residents that we were working to save energy, but also for safety," continues Jean-Luc Eberhart. "We can still refine it. In some places, we could even turn it off."