Energy Saving Potential of Traffic-Regulated Street Lighting

Some municipalities switch off street lights for several hours at night to save energy and reduce operating costs as a consequence of soaring electricity prices in Europe. Complete darkness in the streets raises public concern about safety and security. The current street lighting standard EN 13201 enables the road luminance to be reduced in parallel with diminishing traffic volume offering a viable tradeoff between energy saving and road safety. This paper presents a methodology to estimate the energy-saving potential of traffic-regulated street lighting based on traffic counting data. By analyzing traffic volume and composition collected from an urban street over the one-year period, we found that traffic sensor-regulated street lighting can deliver up to 55% reduction in electricity costs while maintaining road luminance in line with the recommendations of EN 13201-2. In the presented case, the daily traffic volume profiles were remarkably stable following either a workday or a holiday pattern. Statistical analysis showed that 45% energy saving could be achieved by the pre-programmed dimming schedule of the luminaires while remaining compliant with the standard. The effect of daylight-saving time on the energy consumption of adaptive street lighting was also analyzed.