This paper identifies the characteristics of smart cities as they emerge from the recent literature. It then examines whether and in what way these characteristics are present in the smart city plans of 15 cities: Amsterdam, Barcelona, London, PlanIT Valley, Stockholm, Cyberjaya, Singapore, King Abdullah Economic City, Masdar, Skolkovo, Songdo, Chicago, New York, Rio de Janeiro, and Konza. The results are presented with respect to each smart city characteristic. As expected, most strategies emphasize the role of information and communication technologies in improving the functionality of urban systems and advancing knowledge transfer and innovation networks. However, this research yields other interesting findings that may not yet have been documented across multiple case studies; for example, most smart city strategies fail to incorporate bottom-up approaches, are poorly adapted to accommodate the local needs of their area, and consider issues of privacy and security inadequately.

Purpose: This paper investigates the potential contribution of smart city approaches and tools to sustainable urban development in the environment domain. Recent research has highlighted the need to explore the relation of smart and sustainable cities more systematically, focusing on practical applications that could enable a deeper understanding of the included domains, typologies and design concepts, and this paper aims to address this research gap. At the same time, it tries to identify whether these applications could contribute to the “zero vision” strategy, an extremely ambitious challenge within the field of smart cities.Design/methodology/approach: This objective is pursued through an in-depth investigation of available open source and proprietary smart city applications related to environmental sustainability in urban environments. A total of 32 applications were detected through the Intelligent/Smart Cities Open Source (ICOS) community, a meta-repository for smart cities solutions. The applications are analyzed comparatively regarding (i) the environmental issue addressed, (ii) the associated mitigation strategies, (iii) the included innovation mechanism, (iv) the role of information and communication technologies and (v) the overall outcome.Findings: The findings suggest that the smart and sustainable city landscape is extremely fragmented both on the policy and the technical levels. There is a host of unexplored opportunities toward smart sustainable development, many of which are still unknown. Similar findings are reached for all categories of environmental challenges in cities. Research limitations pertain to the analysis of a relatively small number of applications. The results can be used to inform policy making toward becoming more proactive and impactful both locally and globally. Given that smart city application market niches are also identified, they are also of special interest to developers, user communities and digital entrepreneurs.Originality/value: The value added by this paper is two-fold. At the theoretical level, it offers a neat conceptual bridge between smart and sustainable cities debate. At the practical level, it identifies under-researched and under-exploited fields of smart city applications that could be opportunities to attain the “zero vision” objective.

The 15-minute-city concept represents an increasingly popular urban policymaking and planning paradigm that seeks to shift attention to the neighborhood as a “place” rather merely a spatial and functional planning unit. The core premise of the concept is that critical urban services and amenities should be reachable within 15 min of walking or cycling from a residence. The urban-planning principles that enable the realization of the 15-minute city variably embody planning in mixed-use neighborhood units, proximity-based planning, planning for active transport, citizen participation in planning, and innovation and intelligence-driven planning. We revisit these urban-planning premises in the light of emerging social, physical, and structural developments through 2030, with a focus on European cases. The findings provide important additions and recommendations to the urban-planning principles of 15-minute cities along the themes of proximity-based planning, the use of land and urban form, urban governance and citizen participation, and inclusive digitalization. The paper moves the discussion on the 15-minute city forward and will be helpful for urban planners, policymakers, and scholars seeking to envision and create a more sustainable, inclusive, and vibrant future in cities.