Reusing the building elements is the highest possible level of circularity for buildings that must be demolished, potentially slowing down climate change. This study explores the embodied carbon reduction of construction of a pilot building with structural elements of reused concrete. The assessment focuses on applying different methodological approaches and discussing the upscaling opportunities of reusing concrete elements from a global warming potential perspective. The assessment shows large embodied carbon savings compared to conventional building practices like recycling the concrete and building with new low-carbon and prefabricated elements. Embodied carbon saving is also obvious when applying alternative system modelling, future market projection and different allocation approaches of the production emissions of the elements. Finally, the study emphasises the need for further research in evaluating the benefits of reusing structural concrete elements broadly, like including the deconstruction impact related to elements for reuse, to be able to draw general conclusions.

Environmental Product Declarations (EPDs) play an important role in documenting the environmental impacts of building products, particularly reclaimed components, yet their methodologies for allocating impacts remain unclear. This study evaluates the methodology in EPDs for reclaimed components to support the development of harmonised frameworks in EPDs and Life Cycle Assessment (LCA). A systematic analysis of 23 EPDs revealed an increasing trend in EPD publications for reclaimed building products, reflecting a growing industry focus on reuse and transparency in environmental reporting. However, variations in the interpretation of standards, such as EN 15804, were observed, particularly regarding the End-of-Waste (EoW) state and impact allocation for reuse. Current EoW criteria are primarily designed for recycling, creating ambiguity in how reclaimed components are classified and when transitioning into a new product system. The findings underscore the need for harmonised guidelines that explicitly address reuse-specific scenarios and align allocation practices with the modularity and polluter-pays principles to enhance consistency and transparency in environmental reporting. While the observed allocation practices aim to ensure completeness by accounting for all relevant processes, they may inadvertently disadvantage reclaimed elements by making them less competitive than new products. Thus, quantitative analyses of allocation scenarios are recommended to prevent the disadvantageous treatment of reclaimed components, ensuring their competitiveness in the construction sector.

Circular Economy has been highlighted internationally as a solution to mitigate global warming. This study examines the reuse potential of precast concrete elements in Swedish residential buildings, quantifying its impact on element flows and stock using life cycle assessment. While reuse achieves higher carbon savings than recycling, the overall impact remains modest due to limited demolition and high demand for new materials, with most precast concrete elements still embedded in the stock. Assuming all deconstructed elements are reused, savings reach up to 1 % of lifecycle emissions, with a proportional relationship observed between reuse share and embodied carbon savings. Despite aligning with IPCC recommendations for increased prefabrication, the growing precast concrete intensity in buildings with precast concrete structure reflects rising resource consumption. Further studies should assess how technological advancements affect life cycle impacts and reuse feasibility, while also exploring reuse in non-residential buildings and policy measures to strengthen circular economy strategies.

To enable an industry-level transition towards the circular economy, complementary companies and other actors from the focal industry sector, resembling an industrial ecosystem, can jointly increase circulation via reuse or recycling in the system. Although all involved actors must benefit from doing so if their engagement is to be secured, little is known about how industrial ecosystem renewal towards circularity creates benefits. Therefore, this study aims to contribute by applying ecosystem and circular industry development approaches to examine how industrial ecosystems change towards circularity, particularly in regard to the little-studied reuse principle, and identify the diverse benefits of an industry's shift towards circularity via reuse. Thus, this study examines changing industrial ecosystems in the construction industry which have high environmental impacts and focuses on the needed changes to the roles, interactions, and perceptions of ecosystem actors and the diverse benefits gained by increased reuse at company, industry, and societal levels. We conducted an extensive multiple-case study of two industrial ecosystems, namely pilot projects addressing concrete-element reuse, in Finland and Sweden and gathered extensive data covering over 20 interviews, over 18 months of ethnography, and over 300 documents. Our findings show that industrial ecosystems' renewal towards circularity requires changes in the ecosystem actors' roles (role expansions and emergence of new roles), interactions (communication, collabo-ration mindset, utilization of tools), and perceptions (understanding the value of circulated resources, design thinking, and change resistance to conformity). We found that such changes towards circularity generate benefits at the micro level to companies (direct business, competence, and work satisfaction benefits), at the meso level to the industry (environmental, competition, and industry feasibility benefits) and at the macro level to society (environment and employment benefits). Pragmatically, we provide insights and tools for development, business, and sustainability managers, industry associations, and policymakers seeking an increase in circular practices and principles among the industry sectors, involved companies, and surrounding society. Our study contributes to industry-level and sectoral circular economy transformation, reuse, circular construction, and ecosystem research.

In this study, the life cycle environmental implications of modular multi-storey building with cross-laminated timber (CLT) volumetric elements are analysed, considering the product, construction, service life, end-of-life and post-use stages. A bottom-up attributional approach is used to analyse the environmental flows linked to the global warming potential (GWP), acidification potential (AP) and eutrophication potential (EP) impacts of the building for a 50-year reference study period. The result shows that the building’s life cycle impacts can vary considerably, depending on the energy production profile for the operation of the building. The product, construction and end-of-life stages constitute a significant share of the life cycle impacts, and the importance of these stages increase as the energy production profile evolves towards a low-carbon energy mix. For the GWP, the product and construction stages constitute 13% of the total life cycle impact when the operational energy is based on a coal-based marginal electricity. The contribution of this stage increases to 81% when electricity is based on a plausible long-term Swedish average mix. The patterns of the life cycle EP and AP impacts are also closely linked to the energy production profile for the assessment. The analysis shows that a 5% reduction in the GWP impact in the product stage is achievable with emerging solutions for the improved structural design of CLT buildings. This study highlights the need for strategies to improve the life cycle environmental profile of modular CLT buildings.