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Translation abstract Circular and climate‐effective – the new student house in BraunschweigThe new student house at the Technical University of Braunschweig is a multifunctional space that offers space for 200 workstations on over 1000 m2. Without solid walls the two‐story building allows for flexible use. The innovative structural concept is characterized by high resource and emission efficiency as well as recyclability, which is reflected in the reversibility of the primary structure. All components are easily detachable and can be reused in the same or a different combination after the life of the building. The modularly developed structural system can also be easily expanded, reduced or supplemented. [ABSTRACT FROM AUTHOR]

Reuse in new buildings of structural concrete components from demolitions holds the potential for avoiding the use of raw materials to produce new components, including cement for new castings. Reuse rates are high in the circular economy; however, reusing structural components requires documentation of the properties to equate the safety of using reused and new components. Yet, there is no structured or recognized way to perform the documentation. This paper discusses a framework for the documentation requirements for structural concrete, stating the need for documenting the mechanical properties, concrete heterogeneity, and corrosion status of the reinforcement. The possibility is explored for documenting the required properties while the components are in the donor building by use of non-destructive test (NDT) methods. Such use of NDT methods is new. A comprehensive literature survey on the indirect literature, where NDT methods are used to demonstrate similar concrete properties though related to other purposes, is conducted. The overall conclusion is that the use of NDT methods has the potential to document the requested properties before reuse. The next steps towards implementation of NDT for documenting the properties of structural concrete components for reuse involve research in combined NDT methods and the development of AI systems for data interpretation. [ABSTRACT FROM AUTHOR]

A new world record for crude steel production was recorded in 2021, which increased by 3.8% over 2020. This also affected the amount of slag produced with this production. Total waste from industrial and construction production throughout the European Union accounts for as much as 48%. Therefore, waste management should provide for the recovery of as many resources as possible. European Union strategies in line with the circular economy objectives focus on ensuring policy coherence in the areas of climate, energy efficiency, construction and demolition waste management and resource efficiency. Slags are a material of interest to researchers in terms of their use in construction. Slags, on the one hand, are materials that are becoming better understood on the other hand, we are making sure of the heterogeneity of these materials. The characteristics of physical properties of slags are influenced by many factors, including the furnace split in which they are produced. This prompts the search for tools to help determine the parameters of slags based on already available data. The study aimed to verify the hypothesis that it is possible to determine the parameter of the filtration coefficient, relevant to applications in earth structures using the machine learning algorithm – Random Forest. In the study, two types of material were analysed: blast furnace slag and furnace slag. The results of the analysis yielded a high coefficient of determination (R2) – 0.84–0.92. This leads us to believe that the algorithm may prove useful in determining filtration parameters in slags.

The circular economy is one of the main strategies for mitigating the environmental impacts of civil construction due to the generation of construction and demolition waste (CDW). In this transition, evaluating alternatives for using buildings as material banks is a way to make the process of reusing construction components more efficient. Thus, the article aimed to evaluate the state of the art of publications on the relationship between the circular economy in civil construction and the conceptual model of buildings as material banks to mitigate the environmental impacts of CDW. The authors chose the methodological design of Systematic Literature Review, using the Scopus and Web of Science databases for research, with the following search strings: ("construction" or "civil construction" or "built environment" or "construction industry") and ("circular economy" or "circular construction") and ("material banks" or "BAMB" or "buildings as material banks" or "building stocks" or "building materials") and ("construction waste" or "demolition waste" or "CDW" or "construction and demolition waste" or "environmental impacts"). After a screening in which only articles published in journals were selected, from 2013 to 2023, inclusion and exclusion criteria were applied, to evaluate only those that had a direct relationship with CDW management through circular economy strategies and buildings such as banks of material. As a result, 93 articles remained, which were analyzed using a quantitative and qualitative approach. The predominance of applied studies was also noted through case studies that evaluate the management of materials and waste in the urban environment. The qualitative analysis, carried out using a SWOT matrix, highlighted the strengths of the buildings, such as material banks, the potential reduction of resource extraction and urban mining, and promoting the circulation of construction products. However, the recycling of waste, such as aggregates, still stands out as the main end-of-life strategy adopted, even without occupying the top of the waste hierarchy. [ABSTRACT FROM AUTHOR]

A new world record for crude steel production was recorded in 2021, which increased by 3.8% over 2020. This also affected the amount of slag produced with this production. Total waste from industrial and construction production throughout the European Union accounts for as much as 48%. Therefore, waste management should provide for the recovery of as many resources as possible. European Union strategies in line with the circular economy objectives focus on ensuring policy coherence in the areas of climate, energy efficiency, construction and demolition waste management and resource efficiency. Slags are a material of interest to researchers in terms of their use in construction. Slags, on the one hand, are materials that are becoming better understood on the other hand, we are making sure of the heterogeneity of these materials. The characteristics of physical properties of slags are influenced by many factors, including the furnace split in which they are produced. This prompts the search for tools to help determine the parameters of slags based on already available data. The study aimed to verify the hypothesis that it is possible to determine the parameter of the filtration coefficient, relevant to applications in earth structures using the machine learning algorithm – Random Forest. In the study, two types of material were analysed: blast furnace slag and furnace slag. The results of the analysis yielded a high coefficient of determination (R² ) – 0.84–0.92. This leads us to believe that the algorithm may prove useful in determining filtration parameters in slags. [ABSTRACT FROM AUTHOR]

In recent times, the continuous growth of construction and demolition (C&D) activities have resulted in increases in the utilization of natural resources as well as global C&D waste production. A major part of C&D waste produced is dumped in landfills worldwide although some countries have adopted good recycling and reuse facilities to generated C&D waste. Based on an extensive critical review of published literature on the topic including global C&D waste recycling statistics and composition of generated wastes, this paper identifies key physical, mechanical, and geotechnical characteristics of recycled C&D waste aggregates specific to use as pavement base or subbase materials. Recycled aggregates typically have sufficient CBR, abrasion resistance, compressive strength and resilient modulus in accordance with various road standard specifications, which enable their applications for pavement base and subbase layer construction. Recycled aggregates typically have higher water absorption and lower specific gravity values than virgin aggregates. Furthermore, this study evaluates the feasibility and effectiveness of recycled aggregates in pavement base and subbase layers based on the detailed laboratory investigations. Additionally, case studies involving large-volume utilization of recycled aggregates for field-scale pavement construction are presented facilitating the broader adoption of recycled materials in sustainable construction of road pavements. These studies document crucial insights into its real field performance in terms of strength, durability and longevity. Finally, authors have discussed the potential challenges, research gaps and future insights on the use of recycled aggregates in pavement construction. The use of recycled aggregates in pavement construction still has some barriers and challenges such as availability in bulk quantity especially at the field scale and absence of road standards for application, which require further research and practical developments to promote the sustainable use of these materials in the future.

The construction industry faces the rising challenge of circularity, and digital transformation emerges as a pivotal solution. However, limited stakeholder involvement impedes the adoption of digital transformation. The existing literature does not analyze stakeholders' perceptions of digitalization adoption barriers. Therefore, this study investigates the barriers hindering digital transformation in circular construction by examining the varied perceptions of key stakeholders. The study contributes to aligning stakeholders' interests and leads to targeted and effective interventions, enhancing the likelihood of successful adoption. Using the Stakeholder Theory, the study identified contractors, investors, clients, waste managers and government as the most influential stakeholders in circular construction. This study explores skill and knowledge barriers, market barriers, regulatory barriers, organizational and cultural barriers, and financial and resource barriers as key dimensions hindering digital circular practices. The study integrates the fuzzy Delphi method, fuzzy decision-making trial and evaluation laboratory, and analytical network processing to address uncertainties and interrelationships among barriers. The findings indicate that stakeholders hold differing perceptions regarding the most critical barriers; however, there is a consensus that critical aspects are skill and knowledge, organizational and cultural, and regulatory barriers. Practical barriers include lack of government support, resistance to change, lack of feasibility information, lack of training capabilities, and poor digital literacy. The study provides theoretical and practical implications, informing future research and interventions to develop targeted strategies and initiatives.

This study explores the perspectives and practices of architects regarding the reuse of wood in construction across five South–Central European countries: Slovenia, Serbia, North Macedonia, Bosnia and Herzegovina (BiH), and Montenegro. Based on a survey of architectural professionals, this research explores their attitudes, challenges, and motivations for using reclaimed wood, with a focus on circular construction principles. Key findings reveal unanimous agreement among respondents that both their profession and government entities inadequately support or promote wood reuse within the context of circular construction. While architects value reclaimed wood, there are country-specific variations. Environmental benefits, unique aesthetics, historical value, and sustainability are cited as primary motivators for reclaimed wood use. Additionally, respondents emphasize the ecological aspect as the most important consideration in wood product reuse, followed by economic and technological factors. Common concerns revolve around the long-term quality and maintenance of wood products. This research provides insights into the challenges and opportunities surrounding reclaimed wood use in South–Central Europe, highlighting the need for support mechanisms and increased awareness to advance circular construction practices in the region. These findings can have implications for architects and investors by identifying market opportunities, promoting eco-friendly practices, and providing valuable insights for future building designs with a focus on reclaimed wood elements within circular construction. [ABSTRACT FROM AUTHOR]

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This paper proposes an effective approach to realise circular construction with concrete, and shows Unreinforced Masonry as a foundational building block for it. The paper outlines the importance of circularity in building structures. It specifically focuses on the impact of circular construction with concrete on improving the sustainability of the built environment in a rapidly urbanising world economy. Subsequently, the relevance of principles of structural design and construction of unreinforced masonry to achieve circularity is articulated. Furthermore, the paper presents and summarises recent developments in the field of Unreinforced Concrete Masonry (URCM) including digital design tools to synthesise structurally efficient shapes, and low-waste digital fabrication techniques using lower-embodied-emission materials to realise the designed shapes. The paper exemplifies these using two physically realised, full-scale URCM footbridge prototypes and a commercially available, mass-customisable building floor element, called the Rippmann Floor System (RFS). The paper also outlines the benefits of mainstream, industrial-scale adoption of the design and construction technologies for URCM, including accelerating the pathway to decarbonise the concrete industry. In summary, the paper argues that URCM provides a solution to significantly mitigate the carbon emissions associated with concrete and reduce the use of virgin resources whilst retaining its benefits such as widespread and cheap availability, endurance, fire safety, low maintenance requirements and recyclability. [ABSTRACT FROM AUTHOR]

This research investigates the viability of high-strength Recycled Concrete Aggregate (RCA) sourced from demolished structures containing high-strength concrete as a substitute for natural fine aggregates (NA) in cementitious mortar applications. Concrete specimens (40 × 40 × 160 mm) were prepared in a controlled environment with varying percentages of RCA replacing NA, ranging from 0% to 100% in 10% increments. The resulting RCA aggregates exhibited lower weight for sizes from 0.01 to 1 mm compared to NA, and for 1 to 3 mm sizes, RCA weights were 145% to 177% higher than SS aggregates. After curing for 28 days, flexural and compressive strength tests were conducted on the batches. The average compressive strength for the 0% RCA batch was 66.26 MPa, while the 50% RCA batch showed the closest average compressive strength at 63.10 MPa. Batches with varying RCA levels displayed compressive strengths between 49.52 and 58.18 MPa. The highest flexural strength was observed in the 0% RCA batch, with the closest result for a batch containing RCA being the 50% RCA batch. [ABSTRACT FROM AUTHOR]

Climate change has become a global problem, and the construction industry (CI) contributes significantly to this challenge. To circumvent these effects, the circular economy (CE) concept should be implemented in the CI. Developing economies could possess significant potential for implementing CE principles to attain sustainability, particularly in the CI. However, achieving this would require professionals in the CI to adopt some key competencies that should propel success in circular construction. Therefore, this study aims to identify the key competencies required by professionals in the CI to attain circular construction using Ghana as a case study. A quantitative research approach and purposive sampling technique were adopted. After an extensive literature review which showed several key competencies, a cross-sectional survey was conducted among five large construction firms and fifty-two responses from experienced professionals in the industry were obtained. Relative importance index and principal component factor analysis (PCFA) were adopted to evaluate the obtained data. Key significant competency skills for construction professionals to propel circular construction were identified such as specification writing for components and materials, designing for multiple-use cycles, and designing for near-zero energy buildings, among others. Three components were extracted from the PCFA which served as the guidelines for enhancing the competency skills of construction professionals namely, implementing sustainable circular practices, embracing sustainable operations management techniques, and adopting sustainable design principles. In addition, to enhance its practical implications, a competency implementation framework was also developed for construction professionals of developing economies to propel the adoption and evaluation of their competency skills toward circular construction.

Reuse in new buildings of structural concrete components from demolitions holds the potential for avoiding the use of raw materials to produce new components, including cement for new castings. Reuse rates are high in the circular economy; however, reusing structural components requires documentation of the properties to equate the safety of using reused and new components. Yet, there is no structured or recognized way to perform the documentation. This paper discusses a framework for the documentation requirements for structural concrete, stating the need for documenting the mechanical properties, concrete heterogeneity, and corrosion status of the reinforcement. The possibility is explored for documenting the required properties while the components are in the donor building by use of non-destructive test (NDT) methods. Such use of NDT methods is new. A comprehensive literature survey on the indirect literature, where NDT methods are used to demonstrate similar concrete properties though related to other purposes, is conducted. The overall conclusion is that the use of NDT methods has the potential to document the requested properties before reuse. The next steps towards implementation of NDT for documenting the properties of structural concrete components for reuse involve research in combined NDT methods and the development of AI systems for data interpretation.

The global population growth and the imperative to achieve decarbonization goals suggest a re-evaluation of conventional building design approaches. A shift towards sustainability, guided by the Triple Bottom Line principle, becomes essential. In this context, a design paradigm rooted in frugality and creativity can be a promising alternative. This study delves into the role of creative frugality within affordable housing. Through case studies, we showcase technological solutions designed following frugality and creativity. These solutions demonstrate key research findings, such as the relationship between sustainability, circular practices, and frugal, low-technology buildings. These findings are enabled by the concepts of flexibility, adaptability, and disassemblability. [ABSTRACT FROM AUTHOR]

The construction sector accounts for a significant proportion of natural resource consumption and waste generation. This reveals the essentiality for gravitating the operations in the industry toward more sustainable paradigms. To tackle these concerns, the circular economy (CE) model has become a central concept to render conventional production and consumption behaviors in construction projects into innovative and sustainable patterns. In construction projects, selecting the most competent contractor is of paramount importance. Hence, the present research seeks to establish a comprehensive evaluation framework for sustainable circular contractor selection based on a hybrid fuzzy multicriteria decision-making (MCDM) approach. In this respect, the fuzzy analytical hierarchy process (AHP) was adopted for assessing the CE indicators, while the fuzzy technique for order of preference by similarity to ideal solution (TOPSIS) was utilized for evaluating circularity and eligibility of contractors. The utility of the proposed framework was predicated with regard to hydropower projects due to several environmental challenges encountered in the corresponding subsector. The results show that the contractors can be circular only if they have strong financial viability, develop strategies to implement ReSOLVE (regenerate, share, optimize, loop, virtualize, exchange), adopt specific construction methods to CE (e.g., modular construction), and propose sustainable innovative solutions. Overall, the proposed hybrid fuzzy MCDM framework can be used as a more systematic and transparent approach for selecting the most circular and sustainable contractors, contributing to the preservation of earth's resources. Given the current contractors' limited capacity to address circularity and sustainability concerns, the findings of this study can be regarded as a roadmap and contributes to practice by achieving circular and sustainable construction objectives with waste reduction, cost savings, and environmental benefits. [ABSTRACT FROM AUTHOR]

Circular economy (CE) is gaining traction in the construction industry, providing a responsible business model to decouple construction activities from excessive consumption of finite resources. This study conducted a systematic literature review to consolidate and conceptualize the factors that induce and enable construction organizations and stakeholders to adopt CE solutions in the construction industry. The analysis revealed 88 drivers of CE adoption in the construction industry, clustered into eight dimensions, comprising knowledge, organizational, environmental, social, business, regulatory, technological and supply chain drivers. The study further modelled the path dependencies and hierarchical structure of drivers of CE adoption in the construction industry. Thus, the findings provide a holistic insight into the factors inducing stakeholders to adopt CE in the construction industry. The model can provide decision support to develop integrated policies and targeted interventions to facilitate a successful transition to CE in the construction industry. [ABSTRACT FROM AUTHOR]

Construction projects using emerging bio-based materials have been realized over the past ten to fifteen years within Europe. Bio-based buildings utilize properties of natural materials to regulate internal environments, particularly fluctuations in temperature and relative humidity. Despite individual exemplar projects demonstrating functional performance and long-term operational cost savings, there hasn't been a proliferation of commercial or domestic bio-based projects. With a growing shift towards circular economy construction, bio-based buildings could be readily adopted to meet this development. This study evaluates barriers faced by bio-based materials, making the upscaling of production and a breakthrough into mainstream construction challenging. Evaluation was achieved through senior professionals with experience in bio-based construction participating in semi-structured interviews based on core categories of finance, knowledge, and policy. Challenges include the upscaling of production by manufacturers of emerging materials, inconsistencies in life cycle assessment, material certification and accreditation, vested interests in the construction industry, and concerns regarding initial costs, availability, and knowledge of products. Potential solutions for upscaling bio-based construction are identified and include increased case studies, positive legislation, regional economic regeneration, the wellness agenda, long-term economic sustainability, and engagement with established construction companies. This insight has informed the procurement process, material evaluation, and adoption of policy. [ABSTRACT FROM AUTHOR]

The rise of attention to the circular economy in the built environment faces a pervasive problem that buildings are designed to last longer than the careers of those who built them. Predicting how to best preserve and convey information on building construction and materials from the beginning to the end of life is difficult. This paper explores the impact of track and trace technology, specifically quick- response (QR) codes, on reusing elements at the end of a building’s life. In two case studies, we tested the effectiveness of using a material passport (MP) in small-scale construction, providing insights into the digital and physical processes. Ultimately, QR codes are shown to be good stores of static information but are not optimized for dynamic process information during construction life cycles. Despite the challenges of ensuring sustainable, circular construction, the results of this study should motivate those in the construction industry to implement and improve these processes in anticipation of future policy, environmental, and economic demands.

Due to the decarbonization of the energy sector, embodied carbon has been recognized as the dominant climate impact driver. In response, countries are currently accelerating their efforts to comply with climate change commitments and regulations, pressure grows for the construction sector to reduce its impact rapidly. In the present paper, the life cycle assessments (LCA) of purlin roof systems, used as secondary structural elements on single‐story industrial buildings, are compared. Three structural materials are considered: metallic‐coated structural steel, reinforced concrete, and structural timber. In addition, different steel grades are compared to highlight the environmental benefits of using high‐strength steels (HSS) allowing weight‐optimized design. The LCA focuses on the product stage (modules A1‐A3), transport (module A4), end‐of‐life (module C), and the benefits and loads beyond the system boundary (module D). The life cycle inventory (LCI) is composed of construction environmental product declarations (EPD) published according to EN 15804. All the LCA evaluations are performed using the commercial software One Click LCA following the recommendations of EN 15978. [ABSTRACT FROM AUTHOR]

In 2020, 37% of the global share of CO2eq. emissions were attributed to the construction sector. More recently, awareness has been raised on embodied carbon, where emissions from materials and products must be urgently addressed to ensure sustainable constructions. To assess the environmental impacts of a project, a Life‐Cycle‐Assessment (LCA) can be applied: it is a science‐based standardized methodology for quantifying the environmental impacts. It can be used to measure and provide insights to reduce the embodied carbon of constructions over their life. The present publication details the LCA of a wildlife bridge built in France. In addition to the original bridge structure, other structural systems are considered including different materials such as steel and reinforced concrete. The boundary of the LCA is a cradle‐to‐cradle analysis. The life cycle inventory (LCI) is composed of environmental product declarations (EPD) according to EN 15804. The influence of the structural design on the bridge's global warming potential (GWP) emissions and the influence of LCA assumptions (for example, EOL scenarios) are analyzed. This publication aims to support a holistic approach for bridge LCA and help identify the opportunities that can result from implementing sustainable construction strategies. [ABSTRACT FROM AUTHOR]

This study explores the perspectives and practices of architects regarding the reuse of wood in construction across five South–Central European countries: Slovenia, Serbia, North Macedonia, Bosnia and Herzegovina (BiH), and Montenegro. Based on a survey of architectural professionals, this research explores their attitudes, challenges, and motivations for using reclaimed wood, with a focus on circular construction principles. Key findings reveal unanimous agreement among respondents that both their profession and government entities inadequately support or promote wood reuse within the context of circular construction. While architects value reclaimed wood, there are country-specific variations. Environmental benefits, unique aesthetics, historical value, and sustainability are cited as primary motivators for reclaimed wood use. Additionally, respondents emphasize the ecological aspect as the most important consideration in wood product reuse, followed by economic and technological factors. Common concerns revolve around the long-term quality and maintenance of wood products. This research provides insights into the challenges and opportunities surrounding reclaimed wood use in South–Central Europe, highlighting the need for support mechanisms and increased awareness to advance circular construction practices in the region. These findings can have implications for architects and investors by identifying market opportunities, promoting eco-friendly practices, and providing valuable insights for future building designs with a focus on reclaimed wood elements within circular construction.

This research investigates the viability of high-strength Recycled Concrete Aggregate (RCA) sourced from demolished structures containing high-strength concrete as a substitute for natural fine aggregates (NA) in cementitious mortar applications. Concrete specimens (40 × 40 × 160 mm) were prepared in a controlled environment with varying percentages of RCA replacing NA, ranging from 0% to 100% in 10% increments. The resulting RCA aggregates exhibited lower weight for sizes from 0.01 to 1 mm compared to NA, and for 1 to 3 mm sizes, RCA weights were 145% to 177% higher than SS aggregates. After curing for 28 days, flexural and compressive strength tests were conducted on the batches. The average compressive strength for the 0% RCA batch was 66.26 MPa, while the 50% RCA batch showed the closest average compressive strength at 63.10 MPa. Batches with varying RCA levels displayed compressive strengths between 49.52 and 58.18 MPa. The highest flexural strength was observed in the 0% RCA batch, with the closest result for a batch containing RCA being the 50% RCA batch.

This paper systematically reviews published studies involving the recycling and reuse of alternative non-potable industrial and domestic wastewater, seawater, and oil-contaminated water sources in concrete, mortar, and cement paste applications. A summary of available industrial and domestic wastewater sources, their physical and chemical characteristics, optimum treatment methods is presented to provide additional context on potential future reuse of industrial and domestic water sources in concrete applications. Economic implications, gaps of knowledge, and future research needs are also discussed. There are several raw wastewater sources that are mostly aligned with standard water quality thresholds that may produce concrete on par with freshwater systems. In addition, developing specialized water treatments for concrete applications can improve performance, although the water remains non-potable (limited to only primary or secondary treatments).

The transition to a circular economy in the construction industry provides enormous opportunities to decouple construction activities, processes, and practices from finite consumption of natural resources and environmental externalities. Circular construction leverages the interconnected models of narrowing, slowing, and closing resource loops to minimize extractive and wasteful use of natural resources, eliminate waste and pollution from the outset, and retain construction products and materials in use for a longer duration. However, construction practitioners have struggled to implement circular economy principles into construction projects successfully. This study systematically reviewed the critical success factors for implementing circular construction projects. The results revealed 51 critical success factors for circular construction projects, clustered into six typologies: technological (n = 10, ∑ = 93, μ = 9.30), supply chain (n = 14, ∑ = 84, μ = 6.00), organizational (n = 9, ∑ = 82, μ = 9.11), institutional (n = 7, ∑ = 43, μ = 6.14), stakeholder success (n = 7, ∑ = 73, μ = 10.43), and management success factors (n = 4, ∑ = 27, μ = 6.75). A Pareto analysis revealed 30 vital critical success factors for circular construction projects. Thus, the study established the first comprehensive set of critical success strategies for circular construction projects and enriches the knowledge of construction organizations and project team members on how best to implement circular economy principles in construction projects. [ABSTRACT FROM AUTHOR]

This paper provides a multicriteria evaluation model, based on the AHP methodology for the evaluation of the Circular Economy 4.0's, which develops the metric called "Circularity indicator for urban road projects (CIROAD)". The main contribution of this work is to provide a measurement scale specifically designed for urban road infrastructure projects. It is a useful tool to assess the degree of implementation of the principles of the Circular Economy (CE) and the Fourth Industrial Revolution (I4.0) in an integrated manner in these types of projects, generating valuable information for all stakeholders and contributing to the objective of accelerating the transition towards a Circular Economy 4.0 model in the construction industry. The model is defined with twenty-five sub-criteria and seven general criteria, which are: (1) Circular Materials; (2) Circular Design Approaches; (3) Circular Construction Approaches; (4) Circular Operation Approaches; (5) Approaches to Deconstruction and Resource Recovery; (6) Social Value Creation; and (7) Economic Performance. The developed CIROAD model was applied to three projects in the urban transport area of the Chilean Ministry of Housing and Urbanism (MINVU/SERVIU) in the Santiago Metropolitan Region (RM). In these three projects, low performance was observed in terms of CIROAD scores (between 21% and 28% of a maximum of 100%); that is, there is a significant opportunity for improvement by incorporating more circular practices in the development of projects by the studied organization. To accelerate the transition to a circular economy model in the development of its projects, it is proposed that the organization prioritize improving the following circular practices (in order of importance): (1) the design of pavements with environmental criteria; (2) preserving value; (3) conducting cost–benefit analysis (CBA) of waste management; (4) environmental declaration of materials (EPD); (5) the used of recycled materials; and (6) BIM-based design. Finally, the suggestion for the organization in charge of these projects is to use the developed CIROAD model as a tool to support decision making regarding the prioritization of its project portfolio. That is, the organization should use CIROAD to generate a ranking score for each project and allocate resources for investment in the initiatives that show the best circularity performances, as estimated by CIROAD. [ABSTRACT FROM AUTHOR]

The global population growth and the imperative to achieve decarbonization goals suggest a re-evaluation of conventional building design approaches. A shift towards sustainability, guided by the Triple Bottom Line principle, becomes essential. In this context, a design paradigm rooted in frugality and creativity can be a promising alternative. This study delves into the role of creative frugality within affordable housing. Through case studies, we showcase technological solutions designed following frugality and creativity. These solutions demonstrate key research findings, such as the relationship between sustainability, circular practices, and frugal, low-technology buildings. These findings are enabled by the concepts of flexibility, adaptability, and disassemblability.

The goal of optimizing material resources and the polyvalent use of space lead to the development of new technologies within a renewed architectural spatiality, which from the point of view of effectiveness of choices allow for low-carbon buildings. The climate emergency, in fact, asks us today to reinterpret Vitruvius’ concept of Firmitas according to the criteria of durability reliability and resilience associated with widespread usability functionality and circularity (Utilitas) traceable throughout the life cycle a building. The paper illustrates the results of a scientific research project that led to the construction of a prototype of a “minimal” residence, designed and built with the “total low” approach, characterized by regenerative design, economy, lightness, ease of assembly, recyclability, as well as excellent overall performance and high levels of comfort. The idea of a building, easily assembled and disassembled, is a strength of the “Petite-Cabane” design concept: a 3x3 m single-user minimum residential unit made with the Light Gauge Steel Building System (LGS) produced with controlled automatically roll forming machine, for which high technological and energy performance envelope packages. The design of a small house becomes the “mise en forme” of a space in which “essential” equipment, energy performance, architectural qualities, economic and environmental costs are linked to the ease and immediacy of construction but also to the flexibility and circularity of technological choices. [ABSTRACT FROM AUTHOR]

Timber-Cardboard Sandwich (TCS) panels are an emerging class of lightweight and low cost structural composite material, made from bio-based and recycled waste materials. However, there is a lack of data and knowledge as to their compressive behaviours, preventing their structural application as column or wall panel elements. This paper conducts experimental and analytical investigations to address this knowledge gap by characterising the eccentric axial performance of TCS columns. Thirty columns were tested under uniaxial compressive loading, with specimen types developed to investigate the influence of four key design parameters: cardboard core source material, the type and thickness of timber facings, and column slenderness ratio. Test results indicate that the face crushing governing failure mechanism and column ultimate capacity were primarily controlled by the timber facing material, with no observable influence of failure contributions from the cardboard core. Based on experimental observations, analytical models were developed to predict load-carrying capacity and lateral deflection for eccentrically-loaded TCS columns, giving ultimate load predictions within 5% for all studied column types. Research findings provide valuable insights that will enable cardboard to be more widely used in sustainable composite building products. [Display omitted] • Structural performance of timber-cardboard sandwich composite columns is investigated. • Columns achieve high load-bearing capacity with performance governed by timber facings. • Analytical models accurately predict eccentric load capacity and lateral deflection. • Cardboard core material type has minimal influence on structural performance but impacts production cost. [ABSTRACT FROM AUTHOR]

The construction industry faces the rising challenge of circularity, and digital transformation emerges as a pivotal solution. However, limited stakeholder involvement impedes the adoption of digital transformation. The existing literature does not analyze stakeholders' perceptions of digitalization adoption barriers. Therefore, this study investigates the barriers hindering digital transformation in circular construction by examining the varied perceptions of key stakeholders. The study contributes to aligning stakeholders' interests and leads to targeted and effective interventions, enhancing the likelihood of successful adoption. Using the Stakeholder Theory, the study identified contractors, investors, clients, waste managers and government as the most influential stakeholders in circular construction. This study explores skill and knowledge barriers, market barriers, regulatory barriers, organizational and cultural barriers, and financial and resource barriers as key dimensions hindering digital circular practices. The study integrates the fuzzy Delphi method, fuzzy decision-making trial and evaluation laboratory, and analytical network processing to address uncertainties and interrelationships among barriers. The findings indicate that stakeholders hold differing perceptions regarding the most critical barriers; however, there is a consensus that critical aspects are skill and knowledge, organizational and cultural, and regulatory barriers. Practical barriers include lack of government support, resistance to change, lack of feasibility information, lack of training capabilities, and poor digital literacy. The study provides theoretical and practical implications, informing future research and interventions to develop targeted strategies and initiatives. [ABSTRACT FROM AUTHOR]

Revitalization and conversion of a heritage‐protected barn in Gerswalde, Uckermark Rural areas outside of larger cities with their suburbs are currently experiencing a renaissance. Unfortunately, the potential of existing buildings and local structures of the community often remains untapped. Thereby they offer added value beyond the usual architectural solutions for residential or commercial use. The practical example presented below describes the process and constructive measures for making a dilapidated historic barn usable again. The building was stabilized by means of a highly efficient steel structure in terms of minimum additional (space) volume consumption. The flexibility of use was increased by dismantling the inner walls. The planning team successfully dealt with the currently relevant topics of building activity and building culture: revitalization both at building level by making a ruin usable again, and on a village scale by adding attractive and, above all, active businesses in the community; reuse of existing grey energy; circular construction through appropriate material selection and joints; reduction to essential structural intervention to make the existing building usable; regional participation by involving local craft businesses in workshops and in the structural implementation; interdisciplinary collaboration in cross‐trade and holistic‐simultaneous planning of concept, detail and states of construction. [ABSTRACT FROM AUTHOR]

The demand for building materials has been constantly increasing, which leads to excessive energy consumption for their provision. The looming environmental consequences have triggered the search for sustainable alternatives. Mycelium, as a rapidly renewable, low-carbon natural material that can withstand compressive forces and has inherent acoustic and fire-resistance properties, could be a potential solution to this problem. However, due to its low tensile, flexural and shear strength, mycelium is not currently widely used commercially in the construction industry. Therefore, this research focuses on improving the structural performance of mycelium composites for interior use through custom robotic additive manufacturing processes that integrate continuous wood fibers into the mycelial matrix as reinforcement. This creates a novel, 100% bio-based, wood-veneer-reinforced mycelium composite. As base materials, Ganoderma lucidum and hemp hurds for mycelium growth and maple veneer for reinforcement were pre-selected for this study. Compression, pull-out, and three-point bending tests comparing the unreinforced samples to the veneer-reinforced samples were performed, revealing improvements on the bending resistance of the reinforced samples. Additionally, the tensile strength of the reinforcement joints was examined and proved to be stronger than the material itself. The paper presents preliminary experiment results showing the effect of veneer reinforcements on increasing bending resistance, discusses the potential benefits of combining wood veneer and mycelium's distinct material properties, and highlights methods for the design and production of architectural components. [ABSTRACT FROM AUTHOR]

The activities conducted in the building and construction sector should be guided by circular economy principles, which will result in the implementation of greener practices fostering both the development of economy and protection of the environment. This work proposes and discusses an innovative approach based on a concerted strategy between stakeholders to accelerate the transition to a circular construction paradigm, which involves, as sustainable development, the definition of three dimensions to guide the process: (a) the assignment of key roles to the government and construction professionals; (b) the improvement of the industry to perform a proper management of construction and demolition waste; and (c) the development of sustainable practices at the construction site. In addition to the discussion about the different stakeholder partnerships that must exist, key ideas that should be adopted by industry to deliver recycled materials and products to the building and construction sector are proposed in this work. Moreover, measures to assist in the management of both the traditional and innovative materials and products incorporating recycled waste at the construction site are suggested targeting the implementation of more sustainable practices within this context. A broad use of the ideas proposed in this work in the building and construction sector may lead to encouraging outcomes in the next decade. [ABSTRACT FROM AUTHOR]

The net zero as a target: examples for building in line with the reduce‐reuse‐recycle principle The building sector is currently facing an unprecedented challenge: How can we drastically reduce emissions of climate‐damaging greenhouse gases and still meet the growing global demand for a built environment? It is certain that sustainability can only be achieved through a holistic architectural approach. Just as important as taking into account operational emissions are the emissions generated during construction itself. After all, the amount of these embodied emissions produced by 2050 is crucial to achieving the United Nationś climate goals. The three R's of "Reduce – Reuse – Recycle" are essential for the building industry to be able to meet these objectives. In the following, projects are presented that are guided by these three R's and successfully demonstrate how innovative approaches and concepts can drive the change to net‐zero. Among these are the roof of the Olympic Stadium in Munich as a pioneering model for all light‐weight structures, the hanging timber canopy for the 2024 Olympic Aquatics Center in Paris as an example of materials‐based design, the free‐form steel and glass domes of the Moynihan Train Hall in New York City, as well as the modular container stadium serving as examples for preserving and extending the life cycle of structures or entire building components, the City of Dream Pavilion "Cast & Place" made of recycled aluminum, and the youth facility Betonoase in Berlin, whose exterior walls and porches are made of the particularly recycling‐friendly infra‐light concrete (ILC). [ABSTRACT FROM AUTHOR]

It is important to preserve historic buildings in their original conditions, not only to protect building integrity but also to sustain Traditional Knowledge Systems. As stated by ICCROM, those Traditional Knowledge Systems play an important role in the conservation and management of heritage. Among them, building service systems including heating, cooling, ventilation, lighting, drainage, and their architectural construction technology help sustain heritage buildings and extend their life cycle with a minimum level of energy demand. Passive survivability means also contribute to comfort conditions, opening new scenarios for the designing of contemporary buildings. Hence, in this research, first, traditional Kutahya houses were examined in terms of their construction, technology, and architecture. Then, among them, Lajos Kossuth House, dated the 18th century, has been chosen as an exemplary to investigate its traditional building service systems in more detail from the point of circularity in construction, their contribution to circular economy, Cradle to Cradle (C2C) strategies, and design for adaptability principles (DfA). It is observed that they are mostly in a well-preserved condition in terms of both function and character-defining features. However, after 1982, during its refurbishment work to be used as a museum, some of its original details, especially the ones related to waste and clean water were destroyed. To be able to sustain and protect the rest of the original service systems and related architectural construction details in this case study building, they should first be documented, well defined and their recognition should be increased to serve as a model for the maintenance of similar building systems. In addition, it might be possible to transfer the knowledge of those passive survivability means and circular construction principles to contemporary buildings.

This paper aims to be a contribution to establish a position to the reuse of obsolete railway buildings in the field of circular construction. Recent discussions argue that considering that the circular economy is only related to the use of materials or waste is a misconception. The reuse of buildings is also an issue circular architecture. The European Union itself, since 2002, supports the Programme ESPON - European Territorial Cooperation Programme, which incisively inserts obsolete buildings in the "spirit of the circular economy", giving greater attention to industrial areas undergoing change and deindustrialisation. Considering that the concepts of circular construction and circular architecture originated in the circular economy, which emerged as a way to promote and ensure urban sustainability, this article addresses in a first moment the concept of circular construction from the first documents developed in the context of sustainable development to the latest policies proposed by ESPON. It also analyses the reuse of obsolete railway spaces based on the analysis of some emblematic examples of reuse, namely the Musée d'Orsay and the Promenade Plantée in Paris. These two examples represent different types of railway infrastructure and their fate will frame the reuse of railway buildings within the concept of circular construction.

Exorbitant greenhouse gas emissions associated with commercial sodium silicates (SS) have curtailed the large-scale practical implementation of geopolymers and have also led to discrepancies related to their sustainability. As a result, the extraction of SS from silica-rich biomass/agricultural waste ashes (AGWA) have gained the attention of researchers. This process involves heat treatment of AGWA with sodium hydroxide in addition to the calcination to produce the ash itself, thus requiring a systematic study to justify its sustainability. Therefore, this study presents an integrated techno-economic analysis (TEA) and life cycle assessment (LCA) to determine the economic and environmental feasibility of AGWA-derived activators for geopolymer concrete synthesis. The LCA results showed a 60–62% reduction in the greenhouse gas emissions of commercial SS-based geopolymer. A significant improvement was also observed in photochemical ozone formation, wherein the emissions were lesser from binders using AGWA based SS as compared to binders produced with commercially available SS. The TEA indicated that although the AGWA-derived SS reduced the cost of the activator by 50–70%, the overall cost of geopolymer concrete with these activators was still higher than OPC based concrete. The hydrothermal process was found to have a lower CO 2 emissions and production cost as compared to the thermochemical method to prepare AGWA-derived SS. All in all, the innovative valorization of biomass-waste-derived sodium silicate in geopolymer concrete has a lot of potential to foster a circular bioeconomy by closing the loop of agricultural waste and also promote circular construction by repurposing of waste materials in concrete. [Display omitted] • Biomass waste derived sodium silicate can be used as an activator for geopolymer. • 60–62% lesser GHG emissions than commercial SS based geopolymer. • Cost of commercial activator reduced by 40–70%. • Hydrothermal method had lesser production cost than thermochemical method. • Biomass waste derived activators foster circular economy. [ABSTRACT FROM AUTHOR]