**5. Concluding Remarks**

On the basis of the analysis of the various interventions collected in the framework of the ESPON SUPER project, it is possible to develop a tentative set of recommendations and warnings for decision and policy makers aiming at promoting a more sustainable urbanization of their territories. This concluding section rounds off the contribution by presenting these recommendations and warnings, with particular reference to the variable degree of success that actors may achieve when putting in place interventions aiming at different goals and adopting different types of instruments.

In particular, when looking at the scope and the different objectives of the analyzed interventions, the presented evidence shows that land use can be addressed in different ways, none of which, however, are either fully sustainable or unsustainable (Table 4). *Densification* can potentially contribute to achieving sustainable land use if opportunely addressed. For instance, interventions aiming at it have the potential to promote further social equity by reducing car dependency and journey distances [67]. According to the project's results, successful factors of densification are, among others, the adoption of a long-term perspective (e.g., up zoning and measures for infill development), as well as the introduction of legally binding instruments. As shown in the literature [68], densification does not always imply sustainable land use. In some cases, it may contribute to increasing traffic congestion if not opportunely designed [69]; in others, it has been shown to increase housing prices, while it also contributes to reducing green public areas in favor of buildings [70].

Similarly, some of the analyzed examples show that sustainable land use has been successfully promoted by regenerating abandoned areas. *Regeneration* of brownfields requires a paradigmatic shift that makes operative the concepts of reuse and of integrated sustainable development, thereby facilitating a circular use of land [71]. Even regeneration, however, cannot be taken for granted, as it may become more expensive than transforming greenfield sites [72] and thus not economically attractive for market operators due to the cost–benefit logic that development may give rise to. Another inhibitive factor of promoting regeneration is the fact that it may be intended as a tabula rasa without considering local specificity (and community needs) [73], thus paving the way for gentrification phenomena that can lead to social exclusion [74]. *Containment* oriented interventions are among the most common approaches in addressing sustainable land use. For instance, containment can be promoted by restricting the development of city edges, introducing policies to better contain urban expansion [75] and, in so doing, preserving agricultural land from being converted [76]. The information gathered by SUPER seems to sugges<sup>t</sup> that one of the key factors in the success of containment initiatives is the presence of effective political will, since the spatial effect of these initiatives usually takes time to be visible. They also require the establishment of an effective and efficient normative apparatus (e.g., legally binding instruments) that can limit speculative market mechanisms (i.e., increased land prices, exclusion of certain social categories, concentration of development benefits, etc.). However, containment also brings side effects when it comes to sustainable development, such as traffic congestion and an increase in housing prices. In particular, unclear containment strategies may pave the way to increasing land and houses prices, thus forcing individuals and businesses to relocate to areas where more space is available. This kind of spatial competition may reduce the development pressure in one area but drastically increase it in others, making it inconvenient (or undesirable) in terms of sustainable land use [77].

**Table 4.** Successful factors and pitfalls when it comes to promoting sustainable land use (authors' own elaboration).


The mechanism of implementation and models of *governance* are also important in terms of addressing sustainable land use. The most successful ones seem those that integrate public priorities with private (corporate or individual) interests. Effective public and private partnership seems to limit eventual negative externalities that development initiatives may give rise to. According to the research's results, another important factor of successful governance is the establishment of adaptive multilevel collaboration, taking into account that each context is different, as well as the contingencies where the political choices are made. These multilevel governance relations should take care to achieve an optimum balance between top-down and bottom-up approaches. Conversely, uncoordinated governance models and the overlapping of responsibilities seem to act against sustainable development. Due to this complexity, land use can also be addressed by *sectoral initiatives*. As shown, there are a series of examples, throughout Europe, that illustrate how sectoral policies support sustainable land use. In this respect, the success of this kind of initiative may depend on the adoption of an integrated approach and long-term sustainable perspective taking into consideration a multiplicity of sectoral interests. A strong collaboration between the various stakeholders also seems to be fundamental for achieving a good level of sectoral integration and coordination. Accordingly, sectoral authorities should be further integrated in the planning process [78], since sectoral strategies have proven to impact on land use although their impact is not always positive.

The type of instrument to be adopted in order to pursue further sustainable urbanization trajectories is also a highly relevant factor and, in this case too, no one-size-fits-all solution seems available to policy makers (Table 5). For example, the use of *visions and strategies* have proven to be successful when they support common territorial perspectives for territories that share the same needs and challenges and activate cooperative decisionmaking mechanisms. They benefit, moreover, from the establishment of a strong, stable and future-oriented political will that in the long run makes the difference. On the other hand, visions and strategies may fail when the required leadership and/or institutional capacity to translate them into effective measures is missing or when the targets identified are too ambitious and not realistically implementable. That is why decision and policy makers should establish tailored targets in line with territorial needs and effective institutional readiness to translate them into practice. According to the information gathered, *rules and legal devices* have proven successful when they are clear in their final objective (e.g., limit land consumption, protect valuable natural areas, monitor the housing and rental markets) and normatively solid. This is particularly important considering their technical feasibility and the link with their social acceptability. On the contrary, these tools are often less effective when they envisage a large window of flexibility as a consequence of the possibility to interpret the norms discretionally. Failure may also depend on their capacity to address sustainable development holistically. In this respect, decision and policy makers should guarantee an acceptable equilibrium between the various sustainability dimensions (e.g., social, economic, and environmental). If visions and legal devices set the "rules of the game", *land use regulations* are often used to translate them into practices. Through the implementation of regulative plans, decision and policy makers have the opportunity to convert political will and technical capacity into effective land use transformation. That is why it is important to be aware of the factors that have been shown to successfully address sustainable land use. According to the sample, successful examples show an optimum balance between the need for development and the need to achieve sustainable land use. This can be obtained by reorienting planning decisions in order to promote sustainable land use, for instance by reconverting buildable areas into agriculture ones, or protecting land instead of allowing its exploitation. Conversely, planning tools are subject to failure if they directly legitimate speculative phenomena when it comes to facilitating private investments and real estate (gentrification, exclusion of disadvantaged social groups, etc.), while in certain cases they may indirectly facilitate illegal initiatives when plans are hard to implement (lack of effective implementation mechanism).


**Table 5.** Successful factors and pitfalls when it comes to promoting sustainable land use (authors' own elaboration).

> Moreover, the analyzed interventions have shown that even the most concrete strategy or plan may fail if it is not properly supported by effective *programming instruments*. These instruments have proven to be proactive in addressing land use, when well-integrated with existing spatial planning tools and policies. The capacity to mobilize funds effectively is one of the key factors of any initiative towards sustainable urbanization. Mobilizing funds also means implementing real land transformation by developing *projects*. Even though often underestimated, projects are the operative instruments that effectively transform

space. That is why it is important for decision and policy makers to know which are the successful factors that make projects work. In particular, projects are proactive in sustainable urbanization when they are part of a long-term territorial vision without, however, losing sight of short-term objectives. They help to make a strategy visible and concrete thereby creating social legitimacy. Yet, they may only prove fully successful when simultaneously incorporating economic priorities (being cost-efficient), environmental needs (promoting pro-environmental solutions) and social aspects (supporting citizens' involvement). At the same time, projects are often subject to market and political manipulation. Among other factors, policy and decision makers should be aware that in some cases the regeneration (and densification) of sites might facilitate speculative real-estate initiatives.

In conclusion, it is important to recall once again that urbanization processes are a combination of factors that cannot simply be replicated from one context to another, but require a tailored approach [25]. In this view, land use policies cannot be intended as pre-packaged, but should be contextualized according to territorial, institutional, and cultural specificities [79]. Sustainable land use is a polymorphic concept, whose approach can shift from a more ecological and environmental perspective by promoting reconversion of land, establishing ambitious target and strategies, thus promoting a densification of urban structures through the rehabilitation of industrial areas or applying a wide range of incentives and disincentives. In this light, there are a number of messages that decision and policy makers should take into account, namely: (i) to avoid "one size fits all" solutions and thus each policy recommendation should be assessed according to territorial specificities; (ii) to avoid stand-alone initiatives when addressing complex issues like sustainable land use (multi-dimensional, multi-sectoral and multi-stakeholder approaches are preferable); and (iii) to ensure that sustainable land use is a shared responsibility and the identified solutions should be carefully evaluated and shared with all the relevant actors. As pointed out in the Introduction, making careful and prudent decisions on land use is not only a political and technocratic decision but, as the COVID-19 pandemic has dramatically highlighted, also one with highly significant societal consequences [80].

In short, this paper emphasizes the current and future opportuneness of comparative land use studies in a world which is coming to terms with the crucial need to face increasingly challenging issues such as climate change and sustainability as pointed out in the UN Sustainable Development Goals [81]. Nevertheless, it is important to reiterate that, even though there is no "right instrument" or "right target" for all European regions, "right attitudes" exist that can be adopted to promote a more sustainable urbanization, and we hope that the present contribution may constitute a useful support in that direction.

**Author Contributions:** G.C. designed the project and supervised its implementation. A.S. and E.B. carried out data collection and analysis, under G.C.'s supervision. All sections of the paper were written and revised by all three authors. All authors have read and agreed to the published version of the manuscript.

**Funding:** The research was carried out as part of the ESPON SUPER 2019–2020 project (https: //www.espon.eu/super (accessed on 15 March 2021)).

**Acknowledgments:** The research project SUPER (Sustainable Urbanization and Land-Use Practices in European Regions) has been carried out within the framework of the European Territorial Observatory Network (ESPON—https://www.espon.eu/ (accessed on 15 March 2021)). The consortium responsible for the project is coordinated by PBL (the Dutch Environmental Agency) and composed of Politecnico di Torino, BBSR (German Federal Institute for Research on Building, Urban Affairs, and Spatial Development), OIR (Austrian Institute for Regional Studies and Spatial Planning), University of Valencia, University of Warsaw and Urbanex. Additional information concerning the project is available at: https://www.espon.eu/super (accessed on 15 March 2021). The authors would like to thank all the members of the ESPON SUPER team for their proactive cooperation throughout the project.

**Conflicts of Interest:** The authors declare no conflict of interest.
