Light Energy – Efficient and Safe Traffic Environments (2012–2016)
Lighting is a large and rapidly growing source of energy demand; it consumes 19% of the global electricity production. For road traffic, lighting is one of the most efficient road safety measures evidenced by cost-benefit calculations (mean effect on fatal accidents -60%). In search for the most optimised and energy-efficient traffic infrastructure, life cycle costs, service and business models and societal impacts of the new technologies need to be analysed and optimised for the current socio-techno-economical system.
The main objective of Light Energy was to improve the energy efficiency of outdoor lighting without compromising traffic safety. The aim was to combine the multidisciplinary expertise existing at Aalto in the areas of lighting and visibility, metrology, infrastructure modelling, transportation, economical and societal analyses and user-centric design.
The use of optimum level of road lighting maximizes the contrast between the background and the object to be seen. This suggests that the combined effect of road lighting and car headlights should be taken into account. Solutions for the future measurement needs include 3D modelling of lighting environment and mesopic photometry. The life-cycle environmental impacts of high-pressure sodium (HPS) and LED luminaires were found to be on a similar level, but it is expected that LED luminaires will surpass the HPS luminaire in environmental friendliness of the whole life cycle in the future. The energy saving potential is based on new energy-efficient technology, reduced burning hours with smart control and new lighting dimensioning. Energy saving potential when replacing HPS lamps with LED luminaires is 31% with current technology and 66% with improved technology in the future. Further energy savings are achievable with mesopic dimensioning and reduced burning hours enabled with smart lighting. Altogether, the energy saving potential of the future LED luminaire is 85% compared to current HPS luminaire.