How can local authorities effectively address the decarbonization of urban environments in the long run? How would their interests and expertise be aligned into an integrated approach towards decarbonization? This paper delves into how strategic processes can help to integrate diverse disciplines and stakeholders when facing urban decarbonization and presents Cities4ZERO, a step-by-step methodology for local authorities, able to guide them through the process of developing the most appropriate plans and projects for an effective urban transition; all from an integrated, participatory and cross-cutting planning approach. For the development of the Cities4ZERO methodology, plans, projects, and strategic processes from five European cities that are part of the Smart Cities and Communities European Commission program have been monitored for 4 years, in close collaboration with local authorities, analyzing ad-hoc local strategic approaches to determine key success factors and barriers to be considered from their transitioning experiences. The study indicates that an iterative strategic approach and a project-oriented vision, combined with a stable institutional commitment, are opening a window of opportunity for cities to achieve effective decarbonization.

Fossil fuels-based human activity over time has generated unacceptable local levels of air pollution and GHG emissions. One of main implications of this activity is Climate Change, which unforeseen consequences are already impacting at local and global scales. This research is focused on defining an effective framework to shift that trend in the local level through the implementation of the Smart Zero Carbon City concept, which brings together the emerging Smart City paradigm and the 2030/2050 EU goals with the urgent need of decarbonizing our local environments. In this case, the study applies the Smart Zero Carbon City concept and implementation method into 5 EU cities, focusing on the case of Sonderborg municipality (DK) to extract the Key Factors towards Smart Urban Decarbonization, which are applicable to other cities facing this ambitious transition. Keywords: Decarbonization, Smart Zero Carbon City, Smart Cities, Energy Transition

Given the current climate emergency, our planet is suffering. Mitigation measures must be urgently deployed in urban environments, which are responsible for more than 70% of global CO₂ emissions. In this sense, a deeper integration between energy and urban planning disciplines is a key factor for effective decarbonisation in urban environments. This is addressed in the Cities4ZERO decarbonisation methodology. This method specifically points out the need for technology-based solutions able to support that integration among both disciplines at a local level, enriching decision-making in urban decarbonisation policy-making, diagnosis, planning, and follow-up tasks, incorporating the spatial dimension to the whole process (GIS-based), as well as the possibilities of the digital era. Accordingly, this paper explores the demands of both integrated urban energy planning and European/Basque energy directives, to set the main requisites and functionalities that Decision Support Systems (DSSs) must fulfil to effectively support city managers and the urban decarbonisation process.

How can local authorities effectively approach the decarbonisation of urban environments? Recent efforts to redirect cities into a less energy-intensive model have been mostly approached from a sectoral perspective, with specific energy policies and plans being issued without deeply considering their ties with other urban aspects. In this sense, well-established urban planning procedures have not been part of those, with the consequence of barriers in the implementation phase of those energy plans. The Cities4ZERO methodology was developed to guide effective integration between urban planning and energy policies, plans, and practices. It provides a holistic approach to strategic municipal processes for urban decarbonisation in the mid-long term, which includes key local stakeholders’ engagement into integrated energy planning processes, as well as tools for effective energy decarbonisation modelling. This paper analyses the application of the Cities4ZERO decarbonisation methodology on its strategic stage in the development of Vitoria-Gasteiz’s Action Plan for an Integrated Energy Transition 2030 (APIET 2030). It suggests that in order to accelerate urban decarbonisation, it is critical to: (a) foster interdepartmental collaboration; (b) allow for flexibility on the land-use planning regulations; (c) back decisions with detailed urban-energy models; and (d) truly engage key local stakeholders in the planning and implementation processes.

Background Positive Energy Districts (PEDs) are central to the European Union’s vision for climate-neutral cities, offering a transformative model for sustainable urban development. However, their systemic, multiscalar, and interdisciplinary nature introduces significant challenges in both planning and operation. Currently, the support of digital twins to PEDs planning and operation is limited due to technological, organizational, and institutional barriers, as highlighted in previous studies. This study explores the role of digital twins in addressing the complexities of PEDs. Method and results Accordingly, a step-by-step methodology is proposed to guide the development and implementation of digital twins throughout the PED lifecycle, from early planning to operational management. The methodology emphasizes the integration of technological and spatial dimensions and incorporates user experience research (UXR) to ensure effective stakeholder engagement. The proposed methodology was developed within the context of the PED under development at the Politecnico di Torino campus. This case study demonstrates how digital twins can support system design, simulation, real-time control, and transparent reporting, while also enhancing stakeholder involvement. Conclusions All in all, digital twins hold significant potential to overcome the inherent complexities of PEDs, yet their adoption remains limited. The presented methodology offers a structured approach to facilitate their integration, promoting more effective planning, operation, and stakeholder collaboration in PED initiatives.