Background Most of Europe’s energy is consumed by cities and urban areas, which are also the origin of most greenhouse gas (GHG) emissions. Street lighting is a key public service provided by public authorities at the local and municipal level, and it is essential for road and personal safety and overall quality of life in urban communities. As of 2014, there are more than 90 million traditional streetlights in Europe: in most European municipalities, public lighting accounts for 50% of electricity consumption and 60% of energy costs. New solutions such as solid state lighting (SSL) appear very promising because they can lead to savings of up to 50% of electricity and significantly reduce maintenance costs. Moreover, the deployment of energy saving SSL and ‘smart’ adaptive lighting technologies are important elements for sustainable and ‘smart’ cities, in line with the EU Green Paper “Lighting the Future: Accelerating the deployment of innovative lighting technologies” [COM/2011/0889 final], which aims for the rapid and widespread deployment of novel cost-efficient and sustainable lighting solutions. At the same time, state-of-the-art adaptive lighting systems are relatively costly (e.g. computer vision technologies have a payback time of some 30 years), and are only able to monitor areas of some 600 m2 (e.g. gardens and small parks). Objectives The LIFE-DIADEME project will demonstrate a cost-efficient new street lighting dimming system that is designed to reduce energy consumption by 30% in comparison with state-of-the-art control systems. A distributed network of some 1 000 high-tech, low-cost sensors will be installed on a pilot basis in EUR, a residential and business district of Rome. As well as reducing street lighting energy consumption and CO2 emissions in compliance with the CEN 13201 standard on adaptive lighting, the distributed sensor network will enable the monitoring of noise, traffic and air pollution across the participating urban area. It will thus expand data acquisition, promoting more focused and transferable urban climate-related actions and enhancing road safety through the detection of anomalous conditions based on meteorological or traffic statistical data. In so doing, it will further facilitate the implementation of the strictest standards of road safety, climate mitigation and adaptation policies and urban initiatives. The project will carry out a life-cycle assessment, life-cycle cost analysis and preliminary market and socio-economic analyses of the new system, which is expected to reduce street lighting maintenance, contribute to a reduction in national expenditure on public lighting and contribute to the reduction of waste electrical and electronic equipment (WEEE) in compliance with Directive 2012/19/EU. Expected results: The project expects to achieve the following results: Reduce street lighting energy consumption and CO2 emissions by at least 30% compared to the state-of-the-art pre-programmed solutions; Encourage the adoption of 2 million LIFE-DIADEME lighting units in the three years following the end of the project, leading to a saving of at least 159 GWh/yr and a reduction of 55 850 tonnes of CO2/yr; Reduce street lighting maintenance costs by 10%, based on a predicted life-cycle on 20 years for the new system; Save at least 93 tonnes/yr of WEEE for three years following the end of the project, considering the immediate replication and transfer potential of LIFE DIADEME, and 4 180 tonnes/yr assuming EU-wide adoption; Contribute to the reduction by 30% national expenditure on public lighting; and Support the shifting towards green public procurement practices.The project outcomes have the potential to create a significant socio-economic and environmental impact at EU and global level. The project will be seamlessly integrated with green public procurement strategies and future smart cities scenarios, in addition to its important contribution to the update of future climate mitigation and adaptation policies on stricter emissions limits.