Guest Editor’s Introduction to “Sustainable Urbanism: Definition, Assessment, and Agenda for Future Research”

1. Introduction

This Special Issue is based on the premise that urban sustainability (or the lack of it) is a prerequisite for all other efforts toward sustainable development. For it is in cities and towns (and, increasingly, their suburbs) that we interact, move about, consume, emit, deplete, and generate most of our other impacts on the biosphere and on one another. Indeed, it may well be in cities that the battle for true sustainability will ultimately be won or lost.

While cities account for most of our impacts, emerging research demonstrates that they also possess a remarkable capacity to reduce impacts while also delivering an increasing number of human benefits—but only when they function optimally and when their structure supports their functions. As several authors note in this Special Issue, this structure must include a well-connected, walkable public space network as a top priority, along with the supportive edges of more private buildings. This inherent capacity of well-structured cities is a promising new area of research and an encouraging basis for an expanded research agenda.

In this endeavor, the first necessary task is to clarify what we mean by “sustainability”, urban or otherwise. As our Special Issue announcement noted, this term has become commonplace in a variety of fields, and, as such, it has provided a useful interdisciplinary platform for assessment and reform. As we noted, however, too often the term is dangerously ill defined and prone to careless use and shallow claims. The result can be self-delusion, greenwashing, or ineffective strategies at best. Therefore, we need greater precision, as well as a greater capacity to observe, measure, and assess, if we are to accurately identify problems, formulate effective solutions, and make the necessary progress on our sustainability goals.

Accordingly, there is an urgent need to develop more precise and rigorous definitions of urban sustainability, more carefully assess current research findings, and articulate the research agenda to come. That is the aim of this Special Issue. The papers in this first edition only begin this process, and it is our intention to continue this Special Issue into further editions that can explore other essential topics. The authors here are to be commended for a promising start.

First, Alessandro Venerandi, Hal Mellen, Ombretta Romice, and Sergio Porta take up “Walkability Indices: The State of the Art and Future Directions”. Their paper reflects the emerging understanding of walkablity (and walkable public space networks) as a key dimension of urban sustainability; at the same time, they note the need for better measurement methodologies. Their systematic review therefore assesses the state of the art regarding walkability indices and the future research directions needed. Following their assessment, they call for a more aggressive research agenda that employs more detailed descriptions of urban form, balances metric comprehensiveness with data availability, employs robust methods for metric selection, and explores alternative weighting techniques based on cognitive and emotional responses to urban settings. As they conclude, this new research agenda is crucial for advancing our ability to understand and measure walkability in the context of the compact city and place-making paradigms.

Hang Yan and Zhijiang Liu consider the urgent topic of urban health in their paper entitled “A New Perspective on the Evaluation of Urbanization Sustainability: Urban Health Examination”. In the face of rapid urbanization, they note that cities are facing critical challenges of traffic congestion, environmental degradation, resource shortages, and other “urban diseases”. They propose a new methodological framework for evaluating urban health as a dimension of urban sustainability that they term “urban health examination (UHE)”. Their study demonstrates that this methodology can assist decision-makers and urban planners in accurately identifying urban diseases and responding effectively. They note that further research is needed to improve the indicators in order to cover more aspects of urban development and extend the results to other cities.

Elif Öztürk Aksoy and Pelin Dursun Çebi note that sustainable urban spaces require not only the preservation of historical cultural structures but also the expressions of the subjective and collective meanings contributed by the individuals inhabiting these spaces in their daily lives across physical, social, cognitive, and cultural dimensions. These expressions form what they term an “urban-breccia”, a kind of structural amalgam (referring to a kind of stone whose etymology comes from the Italian for “rubble”). This structure, though often hidden, is a key asset of sustainble urbanism, as the authors argue in their paper, “A Conceptual Exploration of Hidden Spatial Layers: Reading Urban-Breccia”.

The need for more accurate measurement using more relevant metrics is explored by Stephanie Bricker, Jan Jelenek, Peter van der Keur, Francesco La Vigna, Sophie O’Connor, Grzegorz Ryznski, Martin Smith, Jeroen Schokker, and Guri Venvik in “Geoscience for Cities: Delivering Europe’s Sustainable Future”. They explore an often-hidden dimension of cities: their geology, and its capacity as a resource for the “mitigation of climate impacts, delivering net zero energy, and implementing nature-based solutions”. Their paper covers topics of geothermal energy, groundwater management, underground infrastructure and buildings, construction materials, seismic and volcanic hazards, and other promising topics. They conclude that for researchers and practitioners, there is a need for a unified conception of the geologies of cities as part of a broader “urban metabolism”. They point to the need for expanded digital technologies to suppport data-driven decision making, and they conclude their paper with more specific recommendations.

To address the vagueness of “sustable urbanism”, in my own contribution, I propose to assess its more readily identifiable opposite, what I describe as “UN-sustainable urbanism”. This phenomenon is readily observable via the alarming global increase in low-density, functionally segregated, often auto-dependent urbanism. Indeed, I find that such a negative assessment is all to easy to perform, with disturbing consequences for any agenda of true sustainability. Nor will it be enough to merely retrofit this deficient form of urbanism with renewable energy or resource systems without recognizing its esssential structural failure. Without thoroughgoing structural reforms, the essential capacities of cities furnished by robust public space networks will remain critically diminished, resulting in further unsustainable impacts. Continuing my assessment, I examine the particular challenge of “lock-in” in its varied forms as a persistent barrier to the implementation of sustainable urbanism. I explore the most promising approaches to overcoming this lock-in, drawing from research in other fields. I conclude with an agenda for further research on this urgent topic.

In spite of the frank discussion herein of the inadequate measures taken to date, the conclusion to be drawn from this Special Issue is a hopeful one. We are capable of identifying the remarkable capacity of cities to meet our needs on a sustainable basis and effectively taking action (including necessary reforms) to support it. As Jane Jacobs concluded in her watershed book The Death and Life of Great American Cities, “lively, diverse, intense cities contain the seeds of their own regeneration, with energy enough to carry over for problems and needs outside themselves”.