ABSTRACT

Introduction Highly efficient light sources are one route to help governments reduce the power consumption of lighting systems and hence reduce the emissions of greenhouse gases in line with the Kyoto agreements. A major area for lighting use is outdoors, especially roadways and streets. The recent emergence of metal halide discharge lamps with ceramic arctubes has lead to a new generation of highly efficient light sources with high colour rendering indices. Further lamp optimisation, coupled with improvements in the ballast characteristics and optical properties of the fixture, together with potential gains from sources specifically designed for human visual perception under mesopic lighting conditions have the potential to dramatically reduce energy usage in roadway lighting. Such systems would simultaneously improve the visual quality, energy efficiency and effectiveness of lighting schemes. For Europe, energy savings of more than 20 TWh could be expected. This energy saving corresponds to a reduction of over 10 million tons of CO, or several big power stations. The resulting reduction in greenhouse gas emissions would be equivalent to approximately 4 per cent of the total EU commitment to the Kyoto agreement.