The circular city is emerging as new concept and form of practice in sustainable urban development. This is a response to the complex and pressing challenges of urbanization, as highlighted in the New Urban Agenda (NUA). The concept of a “circular city” or “circular city-region” derives from the circular economy model applied in the spatial territorial dimension. It can be associated with the concept of a “self-sustainable” regenerative city, as stated in paragraph n.71 of the NUA. This paper aims to develop an extensive form of “screening” of circular economy actions in emerging circular cities, focusing on eight European historic port cities self-defined as “circular”. The analysis is carried out as a review of circular economy actions in the selected cities, and specifically aims to identify the key areas of implementation in which the investments in the circular economy are more oriented, as well as to analyze the spatial implications of the reuse of buildings and sites, proposing a set of criteria and indicators for ex-ante and ex-post evaluations and monitoring of circular cities. Results show that the built environment (including cultural heritage), energy and mobility, waste management, water management, industrial production (including plastics, textiles, and industry 4.0 and circular design), agri-food, and citizens and communities can be adopted as strategic areas of implementation of the circular city model in historic cities, highlighting a lack of indicators in some sectors and identifying a possible framework for “closed” urban metabolism evaluation from a life-cycle perspective, focusing on evaluation criteria and indicators in the (historic) built environment.

The built environment sector is one of the main sources of greenhouse gas emissions and resource depletion that contributes to the climate change crisis. The European Commission, in the “Green New Deal,” highlights that the sustainable regeneration/requalification of existing buildings plays a fundamental role to maximize the objective of decarbonization and resource conservation for 2050. The aim of this study was to understand how historic buildings’ energy retrofit projects can contribute to achieve this goal. In this study, we made a life cycle assessment to evaluate an energy retrofit project of Villa Vannucchi, an historic building located in San Giorgio a Cremano (Naples). The results of this application showed that the use of hemp material, for walls’ thermal insulation, significantly reduces the percentage of environmental impacts in the entire material life cycle (compared with traditional materials). This was because the plant removes a significant percentage of CO2 already from the atmosphere when it is growing. In conclusion, the assessment of different design scenarios that promote the use of innovative technologies and materials can be of high utility to designers to compare and choose efficient solutions for the sustainable/circular renovation of historic buildings.

Abstract:The aim of this paper is to assess the strength and weakness factors of post-industrial cities located in the Gulf of Naples in order to propose the most effective regeneration strategies towards a sustainable development of the urban coastline. This paper focuses on the city of Torre Annunziata and in particular on its industrial port area and waterfront. The analysis suggests that a sustainable development would be possible through the redesign and new functionalization of the waterfront and port area, improving resilience and creativity in order to integrate economic growth, ecological preservation and social opportunities. Thus, this paper is a proposal for a participative approach to the regeneration of the urban waterfront, enhancing the creative potential of the city and developing a new image for the waterfront that could become the strategic vision for a future economic, environmental and cultural development. A comparison between the waterfronts of Torre Annunziata and La Spezia has been carried out in order to assess what are the most effective choices for the future of Torre Annunziata, followed by an applicative process based on interviews.

The challenges of sustainable development are mainly concentrated in the cities. Therefore, they represent a key place for implementing strategies and actions to achieve (or not achieve) sustainable development objectives. In this perspective, the circular city model represents a new way of organizing the city. As demonstrated by a variety of best practices, the entry points for triggering circular processes at the urban scale are various. In this paper, cultural heritage is presented as the entry point for the implementation of this new urban development model. The focus here is on the implementation tools, with a particular emphasis on the evaluation tools for assessing the effectiveness and efficiency of this model, that is, the multidimensional benefits that it can produce. The Level(s) tool, proposed by the European Commission in 2017, is the only officially recognised assessment tool related to the circular economy at the European level. It aims to evaluate the performance of new buildings from a circular economy perspective. This paper intends to expand the field of action of the aforementioned tool to projects related to cultural heritage. Nevertheless, the Level(s) tool has some weaknesses in relation to values and attributes that need to be considered when dealing with cultural heritage. This paper proposes an evaluation framework for assessing cultural heritage renovation and reuse projects, considering all its values and the multidimensional impacts that they are able to produce (economic, social, environmental impacts) in the city. The starting point for the development of the proposed evaluation framework is the Level(s) tool by the European Commission. On the basis of critical considerations, this tool is integrated with criteria and indicators deduced from other previous studies and other official tools on this issue (Green Building Council and Heritage Impact Assessment tools). The evaluation framework is here tested to evaluate the renovation/reuse project of Villa Vannucchi, a historic building located in the city of San Giorgio a Cremano in the metropolitan city of Naples (Italy).

Nowadays, the challenge of climate change and “ecological transition” is substantially an “energy challenge” for every city, which is supposed to become as “energetically self-sufficient” as possible. The construction sector is one of the main contributors to the effects of climate change, starting from the production of materials to the use phase of buildings to their demolition. Recent innovations in sustainable/circular design are related to using “new materials." According to this perspective, nanomaterials are becoming an increasingly widespread practice in various sectors. Nanomaterials are considered very innovative materials able to solve different problems related to buildings' structural and energy efficiency due to their small size. However, the future challenge is to understand whether these materials can be considered “green" from their production stage since risks to human health have been found in both the manufacturing and use and disposal stages. In this regard, an abacus of the most commonly used nanomaterials in the construction industry is defined. Simultaneously, were identified the negative environmental impacts related to the use of these materials, to propose possible solutions to reduce/mitigate them. Therefore, from this analysis, it emerged that a possible solution could be to move to the “industrial biosynthesis process” for producing nanomaterials, according to the circular economy principles. However, this process must always be combined/supported by “Environmental Risk Analysis (ERA)," an evaluation tool capable of identifying and mitigating the adverse negative environmental impacts. The paper concludes with the consideration that new materials for the built environment should be functional and " beautiful," particularly when they are to be used for reuse projects in historic buildings.