4.1. The Key Contributions of Both Smart City and Sustainable City Debates
The first block out of the three we will present in this section is shaped by the most-cited contributions among scholars focusing primarily on smart cities, and those focusing primarily on sustainable cities (see Table 1
). These most-cited papers represent the most-common antecedents used by scholars debating both the smart city and the sustainable city, so they track the path shaping the ongoing debate on the modern conceptions on transforming cities.
The oldest among these contributions are the books authored by Graham and Marvin [69
] and Florida [70
]. Graham and Marvin paid attention to an issue known as “splintering urbanism”—namely, the condition in which some areas of a city are unable to progress as the remaining parts of the same city. The accessibility of services and the development of suitable networks to provide these services are factors indicating the fast modernisation of some areas and, parallel to this, the demodernisation
of other areas. As a consequence, the book calls for actions that improve cities’ quality of life without compromising on the development of any areas. This approach regards sustainability as the achievement of living conditions that are more than passable in every area of a city. However, it should be noted that Graham and Marvin [69
] did not propose “smart city” as a context in their discussion. Instead, they focused on the smart transformation of services. Their main areas of interest related to smart transformation were smart houses, smart energy, and smart highways. Their perspective on city development was related to the need to face cities’ challenges and achieve the best results from the introduction of new technologies. Florida [70
] offered suggestions for smart development; he referred to creativity as the key feature of a social class and some factories, leading to the potential growth of cities. This pursuit of better conditions depended not only on the available technologies, but also on cities’ openness and tolerance. These two features are crucial to the development of the creative industries—a reason why the author stressed the rise of the creative class as a relevant opportunity to support growth. Even in this case, the author did not cite “smart city” as a new issue; however, it is crystal-clear that cities remained an area of focus in the consideration of creativity’s potential benefits. One of the most concrete examples involves considering creativity to be a new path towards the improvement of liveability and sustainability in both cities and suburbs.
Some years later, Giffinger et al. [44
] offered more clarification about what a smart city is, doing so by depicting the six characteristics of a smart city and testing them in medium-sized cities in Europe. Evaluation of the cities was based on a model consisting of “smart economy”, “smart people”, “smart governance”, “smart mobility”, “smart environment”, and “smart living”. These features formed a model that, in the last 10 years, has often been used to plan interventions in cities and to measure the results achieved. One year later, Hollands [71
] labelled these results as progressive. The authors stressed the need to clarify what a smart city is, as differences can exist in the understandings of the interventions performed, as well as in the perceptions of each actor involved. The differences that emerged in the analysis in terms of the meaning of ‘smart transformation’ depended primarily on the approach, as some cities considered equality, while others did not. Additionally, Hollands’ core contribution—useful for further research—depended on the perspective that the definition of a smart city is not based only on cables, new buildings, and technology, but must also centre on changes, living conditions, and progress. These aims were linked to sustainability as a way to frame different goals and combine them in a feasible way while considering the consequences for both society and the economy. Furthermore, from both social and environmental perspectives, sustainability was considered a necessity in addressing the problems that cities face in this era.
A few years later, the multi-disciplinary approach of Chourabi et al. [72
] proposed similar considerations, deepening the elements that shape the path towards cities’ development and considering sustainability to be the strategy that cities wishing to be “smart” should adopt. Furthermore, the combination of liveable and sustainable conditions was considered the crucial factor favouring the achievement of a smart city. Moreover, the authors proposed a framework that depicted smart city initiatives. Most of the items shaping this framework were the same items that Giffinger et al. proposed [44
]. Some of the main differences that emerged during a comparison of the contributions of Chourabi et al. [72
] and Giffinger et al. [44
] were the attention paid to policy and technology as elements directly affecting the development of smart city initiatives. Caragliu et al. [47
] stressed the role of policy makers when describing the relevance of human capital in promoting the improvement of a city’s living conditions; policy makers were urged to focus additional attention on the achievement of equitable urban growth to avoid a situation in which some social classes faced difficult conditions while others reaped great advantages from progress and new initiatives. Additionally, people’s growth in terms of knowledge was considered the key to success, as no policies will last forever and most of the resources that the new initiatives create will decay over time. Consequently, knowledge—and its transfer, sharing, and increase—are crucial to advancing a community’s development. Parallel to this, Batty et al. [73
] adopted a multi-disciplinary perspective by considering the necessary contributions of different fields of science; however, they stressed the role of new technologies in managing, optimizing, and controlling activities in cities. In addition, towards the future city, they drew a path including sustainability, resilience, and rapid changes. In this way, they proposed the description of some scenarios for a smart city through a focus on the main elements such as Information and Communication technologies (ICT), competition, and new proposals for development. The key and novel feature of the model they proposed was its complexity, as it simulated the effects of a project for cities and considered new elements favouring additional interventions [15
]. Complexity is embedded in the notion of sustainability, due to several issues affecting it and the wide set of actors impacting on the achievement of more sustainable conditions.
The results of the aforementioned interventions can be recalled when scholars consider the contribution of Neirotti et al. [74
], who proposed a framework that measured the interplay between socio-economic impact, the resources used to transform a city and its services, and the gap resulting from the comparison between project definition and implementation. Moreover, in line with previous contributions, Neirotti et al. [74
] stressed the relevance of knowledge in relation to all actors: ICT providers should not be the only ones holding knowledge, as open democracy requires the participation of all actors. Only through adequate knowledge can they accomplish their tasks. The need to spread knowledge becomes even more pronounced when one considers that a focus almost entirely on technology would not be enough to achieve liveable cities and favour accessibility. Finally, Vanolo [75
] combined the smart and sustainable perspectives when describing the new paradigms of cities, as a way to think about changes, plan new tangible and social actions, and stress the crucial role that public-private partnerships play in driving cities towards a more participative and successful context for daily life. As a consequence of the focus on participation, to better support the ongoing changes, Vanolo [75
] highlighted the need to assign responsibilities to citizens as concerns their awareness in understanding the context.
4.2. Key Contributions in the Smart City Debate
In the aforementioned analysis, the most frequently cited contributions with respect to dealing with smart cities stressed several elements, although from different approaches. To exemplify the main issues, this paragraph embeds the second block of papers that emerged and will present only some of the elements shaping the debate on smart cities. The most relevant issues in this second block are described in terms of the following three groups, namely the what (the academic debate over definitions), the how (the role of technology), and the with (an overview of the pillars of a smart city). The authors consider these three groups as crucial in supporting the understanding of the antecedents of smart city conceptions; the first group embeds what a smart city is, namely the definitions and the debate about them, while the how depends on the contributions of scholars stressing the role of technology as the way to achieve the planned goals, and the with is representing the pillars depicting the main elements leading to the attainment of the objectives of a smart city. Grouping the contributions represent a process favouring the emergence of topics mirroring the approaches of scholars to a smart city and leading the authors to a comparison with the results of the third block of papers.
The first group of contributions considered consisted of definitions of “smart city”—namely, some of the efforts performed to clarify what a smart city is. In most cases, definitions were compared to each other as a means of stressing which advances were achieved—or least likely to be achieved—when moving from previous approaches to smart transformation. Lee et al. [76
] analysed smart city projects, focusing on the research and development characterising them. Through this research, they achieved a definition of the “smart city context”, doing so through the use of multiple devices and different technologies, but based on roadmaps describing both services and technologies. Thus, they proposed something different from the actors focusing mainly on technology, as the context and its features are more relevant in affecting the transformation. In any event, the roadmap(s) driving cities towards smarter conditions should be customized for the context itself, as alignment with a city’s strategy is necessary. A few years later, Albino et al. [36
] proposed an in-depth analysis of the extant notions of a smart city, seeking to clarify the concept. As an output of their research, they proposed that a smart city is an urban context embedding projects that seek a better quality of life for communities and the use of ICTs. Moreover, they highlighted the difficult task of measuring the results that cities achieved, as a city’s vision greatly affects its aims and, therefore, its achievements. Priorities, resources, and conjunctural conditions significantly affect the goals on the horizon and those that can actually come to fruition. Finally, Shelton et al. [77
] sought to verify the main content of “smart city” definitions, with a focus on those cities implementing projects for transformation and firms supporting local agencies. The authors focused most of their attention on the advantages to be achieved by implementing data-driven governance; thus, they described the limitations deriving from the application of fixed models, due to the fact that they cannot act in line with the specific needs of local communities and conditions.
The second group of contributions highlighted consists of technology, due to the role it plays in the development, monitoring, and management of a smart city. One of the most-cited contributions was Atzori et al.’s [78
] paper about the IoT, as tracking technologies, wireless sensors, and the process of accumulating and sharing knowledge are fundamental to the development of new services in a smart city. Schaffers et al. [79
] expanded the debate when they directly addressed the role of the so-called Future Internet in driving innovation in cities; the authors identified cooperation among actors, open innovation, and both virtual and physical spaces where innovation should take place. In more detail, the focus on living labs is considered particularly relevant when highlighting the interplay among actors, priorities, resources, and policies in favouring cities and urban development. In addition, Gubbi et al. [80
] proposed a focus on the IoT in smart cities and described the elements and technologies that support the achievement of smart environments. Cities are regarded as one of these contexts because a city represents a level in between local communities and national institutions. Furthermore, several elements—such as end-users, local firms, policy makers, and a community’s basic services—affect the development of new policies and interventions. Following this trend in the debate and proposing the new elements arising from other fields of science, Townsend [81
] wrote a book about big data and smart cities; the author described the changes taking place in cities and the ways in which technologies already supported it. Moreover, he stressed the role that big data can play in favouring design, monitoring, and service provision in the smart city of the future.
Finally, the third group of contributions is based on the pillars of a smart city, as in the paper by Nam and Pardo [33
]. They described the role that technology, people, and institutions play in favouring the achievement of smart transformation. Their contribution is relevant because they used the adjective “smart” in relation to people, technology and new elements that should be easy to use, responsive, and useful for providing feedback. All these items are crucial to achieve the goals that the new policies cite. In addition, Angelidou [82
] recalled policies. She stressed the strategic approach towards city transformation; strategies are not easily planned and deployed due to the need to align local strategies with national strategies and to coordinate the actions of several actors. Moreover, deploying a strategy can be complicated because a city’s existing elements can constrain the development of new policies and interventions. Because both tools and goals are new, Lombardi et al. [83
] suggested a focus on innovation when they proposed a model favouring the identification of priorities, the need to create and share knowledge, and the definition of practices to measure performance and, thereby, monitor the goals attained. To describe their model, they table-crossed the six characteristics of smart cities with the three helices. Leydesdorff and Deakin [51
], who maintained a very similar perspective, was often considered because helix-based models are useful in describing the interactions among university-industry-government and the systemic approach to successful innovation. Additionally, innovation was considered the suitable theoretical framework to describe changes taking place in a multi-actor context. This led Zygiaris [84
] to propose the “smart city innovation ecosystem”; the presence of several actors can be observed by analysing the relationship among layers composing the structure necessary to advance smart cities.
To sum up, the following table (Table 2
) shows the three groups of contributions achieved and the main content and contributions related to each of them.
In this way it has been possible to provide evidence on the main contents and favour the comparison with the topics emerging from the block of contributions in the following subsection.
4.3. Key Contributions in the Sustainable City Debate
In this subsection, authors propose the third block of papers, namely the one containing the most frequently cited contributions in the debate over sustainable cities and the key elements shaping this debate. However, as stated before, authors are highlighting only some of the contributions to provide evidence of the main issues and indicate the differences shaping the debate. As done in the previous paragraph, authors gathered the contributions based on the main topics shaping them, and achieved three groups. The first proposes elements of the academic debate over the definition of a sustainable city. The second deals with both social changes and the challenges leading to sustainable cities. The third stresses the key features of this new perspective on cities. As stated in the previous paragraph, authors achieved an overall perspective on the key issues in the debate on sustainable cities and created the right conditions to compare the two conceptions on transforming cities.
The first group proposed includes contributions that involve definitions of sustainable cities, due to this concept’s relevance in the current debate and also because of the numerous comparisons with other notions describing transformations in cities. One of the first contributions proposing such a definition is based on the role of people, as Dempsey et al. [85
] paid more attention to sustainable communities than sustainable cities. In any case, the two topics are greatly intertwined because they both focus on communities as contributors to the attainment of a sustainable context and as beneficiaries of the outputs of transformation in cities. The dimensions useful for depicting the expected advantages for citizens and the pillars of a sustainable city are the interactions in the community, the participation of local members, the stability of the community itself, the pride in being part of a community, and the safety and security of the context. Kennedy et al. [86
] proposed a different approach. They framed a city as a natural system and, consequently, used the metaphor of an ecosystem to describe urban contexts’ need for self-sufficiency. The key concept describing the working mechanisms in a city is described as the metabolism of a natural entity, leading to the proposal of “urban metabolism”. This concept is useful in describing a sustainable city as a bounded context exchanging inputs and outputs with the surrounding area, using technologies and policies to achieve sustainability, and integrating social and scientific perspectives. Finally, authors chose to stress the role of transformation, as Nevens et al. [87
] proposed, when describing actions taken towards a sustainable city. This approach is particularly useful for embedding the planning and implementation, the intervention of local agencies’ and citizens’ contributions, and the urban labs as contexts favouring interactions towards actions. Furthermore, the urban labs—or urban transition labs—are proposed as contexts favouring learning for governance. Therefore, to enable the most suitable actions to be proposed with respect to the changing urban conditions, the managerial approach towards sustainable cities should change along with external elements.
The second group includes all those contributions that deal primarily with the social change framing the context in which sustainable cities are developed. One of the first changes that scholars have highlighted is the increasing density of urban centres and the potential link to the improvement of social equity. Campbell [88
] stressed the contrasting conditions in the planning of urban development and the focus on sustainable conditions. The author believed that a city’s goals compete against each other; thus, sustainability can be achieved only over the long term and through great effort. A balance among the three typical axes of sustainability—social, environmental, and economic—seems to be merely an illusion or something that can be presented only when one is theorizing, as the constant changes taking place in real life make this balance difficult to achieve. With a similar focus on the social scenario containing the features that enable or impede the achievement of sustainable cities, Burton [89
] joined the debate by focusing attention on the link between sustainability in cities and the emerging changes. She began her research using a previous definition of an innovative approach towards cities, namely the “compact city”. This represents the context hosting citizens in a developed world through sustainable models. Urban compactness embeds both consolidation and densification, leading to a city. However, the author observed decreases in terms of liveability when one considered living spaces, the existence of affordable housing, and the availability of spaces for cycling and walking. Meanwhile, transport services, social aggregation, and facilities had greatly improved. Finally (and more recently), global changes have been considered from a wider perspective that embraces natural features and increasing urbanization around the world; Grimm et al. [90
] focused on effects moving from the regional to the global scale and vice versa, underlining the changes affecting human beings and the environment, as well as the interplay between them. This interplay takes place at different levels—local, regional, and global—and is useful for shaping the “urban socioecosystem”—namely, the entire context where changes are taking place and interventions are required.
Finally, the third group consists of contributions that focus on the features of sustainable cities and on strategies to be adopted to challenge current issues. One of the most commonly cited features is resilience; in some cases, this has led to the definition of resilient cities [91
]. Authors often recall a “resilient city” because they think that sustainability should retain its essence even when the unexpected becomes real. A city can be considered resilient when interventions in the infrastructures are based on efficiency and the use of renewable resources. Ways to achieve such a goal with energy are evident; therefore, Newman [91
] encourages identifying mimicked standards as regards the economy, other services such as transport, and biodiversity, as the latter favours the long-term protection of the environment. A similar approach has been proposed in describing the so-called eco-city [92
] as a new form of managing and developing a city from a new mindset. The decision-making processes favouring the emergence of such cities should consider several issues, such as the replacement of new high-tech services with traditional ones, the achievement of social redistribution, the greening of local government practices, and citizens’ participation in defining public policies. An eco-city can be regarded as an initiative to counteract urbanization’s negative effects through a multi-phase project that improves environmental conditions, socio-economic factors, the development of businesses, culture, politics, and international cooperation. Another contribution [93
] considered “resilience” and “eco-city” together; the author regarded resilience as a feature affecting all of a city’s levels and mechanisms. Additionally, resilience should not focus only on external elements and the ability to counteract negative conditions depending on external issues, but also be regarded as a skill necessary to act properly in society. Therefore, the author stressed internal social resilience to highlight the importance of a city being able to face internal shocks.
In summary, Table 3
describes the three groups of contributions proposed and the main contents and contributions shaping each of them.