Search Results (537)

The rapid urbanization process is forcing cities to rethink their development models by adopting circular economy strategies that promote resource efficiency, regeneration, and waste reduction. This systematic literature review investigates how circular strategies are being developed and implemented to support the transition toward circular cities. Following the PRISMA guidelines, 77 studies were selected to provide a comprehensive overview of the approaches currently adopted across different urban contexts. This review identifies a four-macro-level framework encompassing urban circularity strategies, architecture and circular constructions, waste management and recycling, and food sustainability, highlighting both their interconnections and specific challenges. Results show that successful circular transitions depend on the integration of digital innovation, participatory governance, and context-sensitive policy frameworks. However, infrastructural gaps, fragmented regulations, and limited citizen engagement continue to hinder progress. Overall, this review highlights the need for integrated strategies that connect environmental, institutional, and social dimensions to foster more circular, resilient, and inclusive urban systems. These findings contribute to the growing understanding of how cities can operationalize circular economy principles to address sustainability challenges and accelerate the transition toward regenerative urban development. Full article

Urban areas require context-specific bioenergy solutions to advance toward circular and sustainable energy systems. In Bogotá, urban pruning and grass-cutting residues constitute a relatively stable biomass stream; however, the absence of district-scale valorization infrastructure leads to their direct disposal in landfill. This study develops and applies a GIS-based planning methodology to support the territorial design of a small-scale anaerobic digestion plant using urban green waste. In this study, “small-scale” is understood as an early-stage urban facility concept compatible with the available pruning stream of approximately 1200–1300 t/month of valorizable biomass, corresponding only to an order-of-magnitude energy range of a few hundred kW_e/kW_t, rather than to a final engineering design. The approach integrates official geospatial data with logistical, environmental, and institutional criteria to characterize biomass availability and evaluate location alternatives under real urban constraints. A continuous location model based on the Weber problem is first applied to estimate a theoretical lower bound of spatial effort, using public schools weighted by enrollment as a proxy for sensitive urban demand. Subsequently, a GIS-assisted Analytic Hierarchy Process (AHP) is implemented to incorporate environmental exclusions, territorial compatibility, and the operational structure of exclusive waste service areas. Results show that the optimal geometric location diverges from the territorially feasible alternative once environmental restrictions and biomass supply coherence are explicitly considered. The findings highlight that urban bioenergy infrastructure planning is governed less by pure spatial efficiency than by the integration of supply, demand, and institutional constraints. The proposed methodology provides a reproducible decision-support tool for urban bioenergy planning and contributes to sustainable waste management, circular economy strategies, and local energy resilience in cities of the Global South. Full article

The recovery of water and other resources from urban water systems (UWSs) has long been practiced in many Mediterranean countries, but remains relatively unexplored in Croatia. In this study, the sustainable circulation processes of water, nutrients, energy, and their components in UWSs in coastal tourist areas are analyzed in order to strengthen urban systems and environmental sustainability. Dissipative structure theory is used to critically analyze the complexity and sustainability of UWSs, urban systems, and circular economy frameworks. This study is based on conceptual analysis and knowledge (experience), and the sustainability of a circular urban water system is assessed based on circular thermodynamics. This study examines the core concepts of circular urban water systems as a local resource for nutrients, water, and energy, integrating approaches that strengthen resource recovery concepts. Systemic urban climate adaptation and circular urban systems have been adopted as interrelated strategies for resilient cities, focusing on closing resource loops while building resilience to climate impacts through whole-system approaches. This framework moves beyond single solutions, connecting urban planning, energy, water, waste, and social factors to incorporate green and low-carbon developments into cities. It was established that the principle of integrated resource management lies at the heart of effective water, energy, and nutrient management in coastal urban areas, which treats entire urban life support systems as an interconnected system. Such systems increase the efficiency percentages of water, nutrient, and energy recovery while minimizing sludge volume and system entropy, thus supporting the tourism economy and low-carbon development. Full article

In the context of Latin American cities, the management of construction and demolition waste constitutes a strategic challenge. Rapid urban growth and the constrained capacity of disposal sites are generating escalating environmental, social, and economic pressures. Since this waste is generated throughout the life cycle of the building, its management is inherently complex. Consequently, comprehensive planning approaches are essential to mitigate waste generation and advance the reuse and recycling of materials in the construction sector. The methodology combined a systematic review of existing approaches with complementary fieldwork, including a semi-structured survey, interviews, and on-site observations in three construction companies, to identify planning deficiencies and weak practices. Based on these findings, a five-pillar waste management plan was designed, integrating sustainability, cost-effectiveness, and best construction practices. The plan was applied to a high-rise residential building project with a total constructed area of 13,801 m², where the baseline waste generation indicator was 0.32 m³/m², equivalent to an estimated 4410 m³ of C&D waste in the absence of a structured management plan. The plan was validated through a 20-month high-rise building project in Santiago, Chile. Results show a reduction of 1905 m³ of waste (43% below projected volumes), savings of USD 12,273 (35% of the waste management budget), and the recovery of 735 m³ of materials (30% of the total) for reuse and recycling. The final waste generation intensity reached 0.18 m³/m², demonstrating a substantial improvement relative to the initial benchmark and facilitating comparability with other projects through normalized indicators. These outcomes confirm the plan’s potential to enhance environmental performance, deliver measurable economic benefits, and contribute to the transition towards sustainable and circular urban development. Full article

This study investigated how collaboration between academia and local authorities creates sustainable frameworks for addressing urban challenges through environmental, social and governance (ESG) principles, benefiting both education and the long-term resilience of cities. The paper discusses how establishing dialogue and setting common aims between educational institutions and local authorities, by adopting Participatory Action Research (PAR) approach, enables architecture schools to address civic responsibilities while advancing ESG goals in urban development. The collaboration addresses environmental sustainability through circular economy principles, promotes social inclusion through community engagement, and establishes transparent governance through institutional partnerships. This collaborative model was developed through three summer workshops in Aberdeen, delivered before the pandemic, which helped bridge the gap between theory (academic and educational hypotheses) and practice (tangible urban challenges facing public organisations). This unique experience, named Aber-net (reiterating the intention of creating a network of collaborations), demonstrated how merging research, professional expertise and educational frameworks can create ESG-driven partnerships that support responsible urban development, a model currently underrepresented in the UK. In conclusion, the paper discusses how these collaborative activities improved the perception of public spaces in Aberdeen while establishing a replicable ESG-aligned framework for sustainable partnerships. It examines the challenges and opportunities of creating academia-practice networks that embed ESG principles into urban development. Full article

Methane emissions from abandoned coal mining operations represent a persistent environmental and safety challenge in post-mining regions undergoing urban redevelopment. As urban infrastructure expands over former underground workings, the uncontrolled migration of mine gas can compromise public safety, exacerbate greenhouse gas emissions, and undermine sustainable development goals. This study investigates the origin of methane emissions detected in an urban area of the municipality of Lupeni, Romania, following the commissioning of a new natural gas distribution pipeline installed within a historically mined perimeter. The emissions had not been previously reported and were unexpectedly discovered during technical inspections conducted after the gas network installation, highlighting the absence of historical data on gas presence in this area. This is the first documented case of an accidental discovery of methane emissions in an urban perimeter overlying historical coal mine workings in Romania, granting this study a pioneering status, both scientifically and in terms of urban risk management. The findings emphasize that administrative mine closure does not equate to risk closure, as latent methane emissions may reactivate during urban transformations (e.g., excavations, utility upgrades, drainage changes). To ensure a scientifically sound and sustainable risk assessment, an integrated diagnostic framework was applied, combining chronological field monitoring with chromatographic gas composition analysis. This methodology enabled precise attribution of the methane source to abandoned underground mine workings, excluding the public gas network as a contributor. Based on this diagnosis, a controlled drainage and methane recovery system was implemented, resulting in the elimination of detectable concentrations at all monitoring points by February 2025. The captured methane was redirected for local energy use, transforming an environmental liability into a usable resource. This intervention supports circular economy principles and aligns with EU climate and energy transition goals. The proposed methodological framework provides a replicable model for identifying and managing residual mine gas in post-industrial urban environments. Although emission fluxes were not quantified, concentration-based screening enabled risk diagnosis, prioritization, and targeted intervention. These findings are relevant to EU Regulation (2024/1785) on methane emission reduction, emphasizing the need to include post-mining methane (AMM) in urban planning and environmental monitoring strategies. Limitations of the study include the absence of baseline data and the inability to calculate total methane flux. However, the results support immediate and practical risk mitigation and highlight the need for future work focused on long-term monitoring and emission quantification. This case provides critical insights for other post-mining cities in Central and Eastern Europe facing similar challenges at the intersection of legacy coal infrastructure and modern urban development. This study is designed as a concentration-based diagnostic and risk-oriented case study and does not aim to quantify methane emission fluxes. Full article

Urban built environments face unprecedented challenges in resource management and sustainability, necessitating innovative approaches that integrate circular economy principles with construction technologies. This study addresses the critical research gap at the intersection of circular city initiatives and modular integrated construction (MiC) by employing a structured literature review methodology to systematically analyze existing knowledge. Following PRISMA guidelines, the search screened 438 papers (209 on MiC, 229 on Circular City Initiatives), of which 68 papers were included after quality appraisal for thematic synthesis using MAXQDA. The analysis offers a structured basis for operationalizing circular economy principles in the construction sector and provides a roadmap for future inquiry. The research develops a conceptional requirement matrix framework that bridges circular city principles with MiC implementation. Through systematic analysis, the study establishes six key requirements for construction technologies resulting from circular city initiatives and evaluates them against the six key MiC characteristics: prefabrication and assembly; speed and efficiency; quality and safety; standardization and mass production; sustainability; integration with technology. This matrix represents the first systematic approach to operationalizing circular economy principles through modular construction methodologies. The framework reveals that MiC constitutes a transformative paradigm for circular urban development through multiple synergistic pathways: prefabrication enhances reversibility and durability, extending service life and enabling material loop closure; eco-design integration improves safety and quality standards; deconstructability facilitates adaptive reuse; and BIM-based tools enhance material efficiency and recycling capabilities. The requirement matrix demonstrates strong alignment between circular city requirements and MiC characteristics, with adaptive reuse and modularity showing the strongest correspondence. Stakeholder engagement and policy support emerge as critical enablers across all implementation dimensions. While the framework is grounded in a structured literature review, it remains theoretical and serves as a foundation for future empirical validation. Full article

This article proposes a strategic framework for Kyiv’s post-conflict sustainability and resilience under brittle, anxious, non-linear, and incomprehensible (BANI) conditions. We integrate adaptive governance, circular-economy reconstruction, and city-scale digital capabilities, including AI-enabled analytics, IoT sensing, and urban digital twins. Building on recent assessments of Ukraine’s reconstruction needs, we outline a socio-technical model that links sustainability and resilience objectives under shock risk and budget constraints and show how an illustrative five-year optimisation can rebalance investments toward distributed renewables and early-warning infrastructure. The example portfolio achieves an end-horizon composite performance of F_optimized(5) = 0.65 (on a 0–1 normalised index where 1 indicates achieving the policy-defined targets; 0.65 indicates ~65% progress toward those targets at year 5, improving on the baseline allocation under shocks), indicating improved robustness relative to a baseline allocation. We emphasise that effective implementation depends on secure-by-design digital architecture, participatory prioritisation of indicators and weights, and iterative monitoring that supports rapid adaptation as conditions evolve. The framework provides a pragmatic roadmap for Kyiv and similarly vulnerable cities seeking a low-carbon recovery while reducing systemic brittleness and mitigating anxiety-driven decision-making delays. Full article

The growing demand for low-carbon, resource-efficient, and multifunctional construction materials has intensified interest in solutions that can support both circular economy strategies and sustainable urban development. Expanded perlite—a lightweight volcanic material with low embodied energy and multiple functional properties—is increasingly considered a potential component of circular and nature-based material systems. This paper critically examines whether expanded perlite can serve as a sustainable alternative in civil engineering applications, contributing to reduced material consumption, improved thermal performance, and lower environmental impact across the life cycle. The review provides an overview of current applications of expanded perlite in lightweight concretes, insulation systems, green roofs, water-retention substrates, and other technologies relevant to resilient and net-zero cities. It also identifies key research gaps related to long-term durability, large-scale implementation, and life-cycle assessment, while emphasizing the need for proper handling procedures due to health concerns associated with dust exposure. By situating expanded perlite within the context of circular design and low-carbon construction, the paper highlights its potential role in decarbonizing the built environment and advancing the transition toward climate-resilient and regenerative urban systems. Full article

In the context of the European Green Deal and the New European Bauhaus, circularity and sustainability have emerged as central paradigms for rethinking development models in both urban and rural areas. While most literature focuses on cities, rural villages are increasingly recognised as living laboratories where cultural heritage, landscape values, and community-based practices can support sustainable and responsible tourism. This study applies the Circular Development framework to 54 European case studies of rural regeneration, examining the interrelations among cultural heritage enhancement, sustainable tourism, circular resource management, and community engagement. Through a mixed-methods approach combining frequency and cluster analysis, the research identifies strategic domains and recurring configurations of actions, contributing to the definition of a conceptual model for the Circular Rural Village. Three pillars (Circular Tourism, Circular Land, and Circular Living) articulate how cultural identity, experiential tourism, ecological regeneration, and participatory governance can foster integrated and sustainable development. The findings offer insights for policy-makers and practitioners aiming to activate regenerative tourism and heritage-led circular transitions aligned with sustainability goals. Full article

Sustainable urban water system (UWS) management is vital for climate-resilient, resource-efficient cities. This study presents the first comprehensive life cycle assessment (LCA) of Seoul Metropolitan City (SMC)’s UWS, encompassing water abstraction, treatment, distribution, wastewater collection and treatment, and sludge management. Nine midpoint impact categories from ReCiPe 2016 (H) were analyzed to identify environmental hotspots and mitigation pathways. Results show that wastewater treatment dominates impacts, contributing 57.3% of global warming potential (GWP; 0.947 kg CO₂-eq per functional unit of 1 m³ of potable water supplied) and 71.1% of freshwater eutrophication (FE; 0.00066 kg P-eq/m³), driven by electricity use, sludge disposal, and direct CH₄/N₂O emissions. Electricity consumption is the leading driver across GWP, terrestrial acidification (TA), and fossil resource scarcity (FRS). Infrastructure construction notably influenced terrestrial ecotoxicity (TET) and human toxicity. Sensitivity analysis showed that SMC’s projected 2030 electricity mix could reduce GWP and FRS by up to 18%. Scenario evaluations revealed that sludge ash utilization in concrete and expanded wastewater reuse improve resource circularity, whereas biogas upgrading, solar generation, and heat recovery significantly lower GWP and FRS. The findings underscore the importance of energy decarbonization, resource recovery, and infrastructure longevity in achieving low-carbon and resource-efficient UWSs. This study offers a transferable framework for guiding sustainability transitions in rapidly urbanizing, energy-transitioning regions. Full article

In urban plantings, mined sand and scoria are commonly used as low-nutrient substrates to improve plant establishment and growth. However, reliance on mined materials conflicts with sustainability policies promoting resource circularity and waste reuse. Construction wastes are readily available, and while their high alkalinity and density may limit plant growth, incorporating organic matter, like pine bark, can ameliorate these issues. We investigated whether construction waste amended with pine bark can support plant growth. We evaluated physical and chemical properties of 12 substrates combining four mineral components—scoria (mined), sand (recycled), crushed concrete (recycled), and crushed rock (recycled)—with pine bark (10%, 20%, and 50% v/v). We then tested eight of these substrates in a container experiment, evaluating the growth of two woody shrubs: Alyogyne huegelii and Goodenia ovata. All mineral components were alkaline (pH 9.2–12.3), with crushed concrete remaining hyper-alkaline despite pine bark addition. Greater pine bark volumes improved air-filled porosity but reduced water retention. Substrates with 50% v/v pine bark had lower plant biomass compared to those with 10% v/v. However, plant biomass was similar across all mineral components. This demonstrates that construction waste–pine bark substrates can support plant growth in urban plantings, supporting broader sustainability goals in cities. Full article

In the face of accelerating climate change and urbanization, sustainable mobility infrastructure plays a critical role in reducing greenhouse gas emissions. This article assesses the Sunglider concept—an elevated, solar-powered transport system—through the New European Bauhaus (NEB) Compass, which emphasizes sustainability, inclusion, and esthetic value. Designed by architect Peter Kuczia and collaborators, Sunglider combines photovoltaic energy generation with modular, parametrically designed wooden pylons to form a lightweight, climate-positive mobility solution. The study evaluates the system’s technological feasibility, environmental performance, and urban integration potential, drawing on existing design documentation and simulation-based estimates. While Sunglider demonstrates strong alignment with NEB principles, including zero-emission operation and material circularity, its implementation is challenged by high initial investment, political and planning complexities, and integration into dense urban environments. Mitigation strategies—such as adaptive routing, visual screening, and universal station access—are proposed to address concerns around privacy, esthetics, and accessibility. The article positions Sunglider as a scalable and replicable model for mid-sized European cities, capable of advancing inclusive, carbon-neutral mobility while enhancing the urban experience. It concludes with policy and research recommendations, highlighting the importance of embedding infrastructure innovation within broader ecological and cultural transitions. Full article

Rapid urban growth in many Global South cities strains waste systems and slows the shift to circular economy (CE) practice. Colombo, Sri Lanka, exemplifies this challenge, where overstretched state-led services coexist with neighborhood groups, NGOs, and informal collectors driving circular activities. This study adopts a layered social network diagnostic framework to examine how community-based waste management networks operate and how they might be reshaped to enable a city-wide CE. Using survey and interview data from 185 actors, information-sharing, collaboration, and resource-exchange networks are analyzed separately and in combination. The results reveal three principal findings: (i) Social-capital forms operate largely in parallel, with limited conversion between information, collaboration, and material exchange; (ii) the network exhibits “thin bridges and thick clusters,” in which a small number of NGO hubs mediate most cross-cluster connectivity; (iii) layers operate with mismatched coordination logics, producing gaps between awareness, collective action, and resource mobilization. As a result, ideas circulate widely but rarely translate into joint projects, local teams coordinate effectively yet remain isolated, and material flows depend on a narrow and fragile logistics spine. By diagnosing these structural misalignments, this study demonstrates a key novelty: scalable circular economy adoption depends not only on technology and policy but also on the design and alignment of underlying coordination networks. Full article

This article examines the role of coworking and flexible workspaces in promoting sustainable spatial development in the non-metropolitan areas of Bulgaria. A mixed-method approach was applied, combining inventory enumeration, spatial classification, SDG-based sustainability assessment, and qualitative coding (open, axial, selective). A total of 74 coworking and flexible workspaces were identified across the six national planning regions, evaluated according to six analytical criteria (accessibility, seasonality, specialization, municipal administrative district, urban planning zone, building function) and assessed against five SDG-aligned dimensions (SDG 8, 9, 11, 12, 13). The results reveal uneven territorial distribution, strong concentration in major cities outside the capital, and emerging sustainable models in peripheral areas. Comparative SDG scoring and typological interpretation demonstrate three recurring models—Sustainable Reuse, Nature-Oriented, and Innovative/Experimental—each associated with distinct spatial and environmental characteristics. A metropolitan benchmarking exercise further contextualizes the strongest sustainability profiles. Based on these findings, a conceptual sustainable coworking model is developed for a nationally significant spa and climatic resort, illustrating how coworking can address regional disparities, support green transition policies, and reinforce territorial cohesion. The article concludes by outlining research directions related to digitalization, circular construction, environmental performance indicators, and feasibility assessments for non-metropolitan coworking development. Full article