## 1 Introduction  
Energy consumption for urban street lighting has assumed considerable importance in the energy and economic balance for many cities [1, 2]. Public lighting systems are a major source of electricity consumption: at present 3.19% of global electricity generation is used for lighting. This amount is greater than production of all hydro or nuclear plants and equals the production from natural gas [3]. It is widely recognized that public lighting is a sector characterized by excessive and disproportionate energy consumption compared to the quality and functionality of the service offered to the citizen. This implies the need for tools to improve the energy performance of urban street lighting, such as new technologies, professionalism and analytical/design skills [4]. A study carried out by ENEA (the Italian National Agency for New Technologies, Energy and Sustainable Economic Development) reports that the \"energy wastage\" of urban street lighting systems in Italy currently accounts 30% of consumption on average [4]. This highlights the role and potential of energy efficiency processes of street lighting systems, not only in terms of environmental performance (due to reduction of energy consumption and emissions of CO\({}_{2}\) into the atmosphere), but also in termsof economic and financial performance (due to the reduction of economic costs of bills, which today heavily burden municipal budgets). The strategic role of the public lighting sector as a drive for the economic, technological and social development of cities justifies the increasing commitment of city authorities to energy efficiency and green energy public lighting systems. The European Community provides several policy tools in order to achieve these savings. One of the most important is the \"Covenant of Majors\" (4400 partners of which 2100 are Italian Municipalities) which groups local and regional European authorities, with these groups voluntarily committing to improving energy efficiency and the use of renewable energy sources on their territories [5]. The increasing attention reserved by practitioners and city authorities to the topic has been accompanied by the development of much research in the field. Most of the existing studies aim at developing optimization models for selecting the right energy efficiency measures among a set of alternatives, by looking at the whole street lighting system or even parts of it. [PERSON] and [PERSON] [6] propose a consumption reducing solution based on an intelligent system for remote sensing and control with dimming technologies of HID (high-intensity discharge) lamps. [PERSON] et al. [7] develop a tool for an optimal lighting system design aiming at reducing both costs and distortion of the whole lighting system. [PERSON] et al. [1] investigate the effect of three strategies on the performance of street lighting systems: the first consists of adopting lighting controllers on each switchboard, the second of changing the existing lamps with LED (light-emitting diode) luminaires, and the third involves combining both of the previous strategies. [PERSON] et al. [8] develop a multi-criteria decision-making tool to support the public decision maker in optimizing energy retrofit interventions on existing public street lighting systems. [PERSON] et al. [9] propose a multi-criteria decision-making approach for selecting optimal technical and economic solution for public lighting system. [PERSON] et al. [10] propose a multi-objective methodology (including lighting, energy and economic parameters) for street lighting systems refurbishment evaluation in small/medium sized Italian towns.