This study explores the climate change effects of building with wood structural frames in a life cycle perspective, with a focus on biogenic carbon. Analyses of a timber-frame building are carried out considering fossil and biogenic carbon flows during the production, construction, use, and end-of-life stages of the building. Both static and dynamic life cycle modelling are used and compared, to understand the implications of different biogenic carbon accounting methods, including a simplified approach and an entire chain approach integrating biogenic carbon flows from forestry, construction, and energy sectors. The findings show significant differences between the modelling approaches. Over a 100-year analysis period, the static modelling with simplified biogenic carbon accounting indicates a building life cycle climate impact of 164 kgCO₂e/m², and is the same when excluding and including biogenic carbon flows. The dynamic modelling with simplified biogenic carbon accounting indicates a life cycle climate impact at year 100 of 199 and 91 kgCO₂e/m² when excluding and including biogenic carbon flows, respectively. The corresponding life cycle climate impact for dynamic modelling with entire chain accounting of biogenic carbon flows is 51 kgCO₂e/m². The production stage dominates the building's life cycle climate impact, with insulation contributing the most. Overall, the dynamic modelling of biogenic carbon flows across the entire chain results in a significantly lower life cycle climate impact for the building. This study underscores the importance of robust accounting for GHG emissions, including biogenic carbon, to optimize the climate impacts of wood-based buildings.

The construction sector is a major contributor to global resource consumption and environmental degradation. Circular Economy (CE) has emerged as a transformative framework for sustainable construction, promoting resource efficiency, waste reduction, and regenerative practices. To enable advancement, this study conducted a Systematic Literature Review (SLR) of 384 peer-reviewed articles to map CE strategies in construction, assess their impacts, identify solutions, and highlight research gaps. The review reveals a growing academic interest in CE, yet the practical implementation of CE strategies remains limited. The thematic analysis categorised CE impacts under the three pillars of sustainability: economic (e.g., cost savings, market innovation), environmental (e.g., waste minimisation, decarbonisation), and social (e.g., job creation, stakeholder engagement). Solutions identified were synthesised into four overarching categories: Foundational Enablers, Design and Planning, Implementation, and Innovation and Knowledge-Building Solutions. Despite promising developments in CE in the construction context, the study identifies critical gaps: limited empirical validation, underexplored social impacts, fragmented implementation frameworks, and insufficient integration of digital technologies. The dominance of recycling over more sustainable strategies like reduction and reuse also reflects a partial transition toward circularity in the construction sector. The paper calls for interdisciplinary research, harmonised metrics, and collaborative ecosystems to advance CE adoption in the construction sector. By offering a comprehensive synthesis of CE strategies, impacts, and gaps, this study provides actionable insights for researchers, policymakers, and industry stakeholders. It advocates for a systemic shift toward regenerative, low-carbon, and resource-efficient construction practices, aligning CE principles with broader sustainability goals.

In an era of environmental awareness, the construction industry faces pressure to adopt resouurce-efficient practices that reduce waste, extend material lifespans, and support climate change mitigation. While the environmental benefits of multi-storey wood buildings (MWBs) are well recognized, understanding and evaluating circular economy (CE) applications in this context remains limited. This study explores CE strategies for MWBs, examines circularity indicators, tools and methods for evaluating CE, and identifies challenges hindering the application of CE in MWB construction through a systematic literature review. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocols, a structured search was conducted in the Web of Science and Scopus databases using relevant keywords. A total of 34 relevant studies were selected from an initial list of 347 studies. The results indicate that key CE strategies were increasingly implemented at the early-stage of MWBs. However, limited CE implementation exist at the end-of-life stage of MWBs. Key challenges to CE MWB construction include risk-averse approach of designers and engineers, the lack of standardized data and methodologies for end-of-life assessment, insufficient conceptualization and categorization of CE principles due to limited knowledge and education, and limitations in current life cycle assessment methods. The study highlights significant limitations in circularity indicators and evaluation methods, emphasizing the need for further research to advance CE integration in MWBs. By systematically synthesizing the state-of-the art research on CE practices in MWBs, this study presents a framework that highlights key challenges, knowledge gaps, and research priority areas for advancing circularity in MWBs.  

Careful selection of construction materials and the efficient management of post-use materials are vital for resource-efficient buildings with lower environmental impacts. This study explores the implications of circular economy practices, entailing efficient post-use materials recovery for reduced environmental impacts of cross-laminated timber (CLT) multi-storey construction. The global warming potential (GWP), acidification potential (AP) and eutrophication potential (EP) of a CLT building are explored in a life cycle perspective, including include all building materials-related activities in the product, construction, end-of -life stages, with a focus on circularity strategies - cascading, reuse, and recycling of post-use building materials. The results show that the building's end-of-life stage represent a significant share of the total life cycle GWP impacts. However, the stage represents a relatively smaller share of the AP and EP impacts. The implementation of circulatory significantly reduces the life cycle climate impacts of the building. The end-of-life stage, which represents about 20% of the total material-related GWP impact, can be effectively mitigated through these circularity strategies. Cascading proves to be a better option compared to reuse and recycling, offering a GWP benefit of 70kgCO_2eq/m2. Comparatively, the GWP benefit from cascading is 64% and 72% higher than that of the reuse and recycling options, respectively. This study highlight the importance of life cycle perspective and circularity strategies at the end-of-life stage of CLT buildings to reduce environmental impacts. 

Buildings are a major contributor to environmental impacts and energy consumption within the European Union. Consequently, the EU has established specific targets and policies for improved building energy and environmental performance, with the Renovation Wave being one of the most notable initiatives. However, current strategies mainly focus on energy efficiency in the operational phase of buildings, overlooking the embodied impacts from materials usage during the production, construction and retrofitting phases. Moreover, the emphasis on renovations and the neglect of alternative case entailing building demolition followed by reconstruction could present limitations in decision-making. Few studies provide comprehensive comparative assessment between renovation or reconstruction in a residential context. In the few studies which employ life cycle assessment methodology, the end-of-life stage and the potential benefits from recycling of materials are not considered in the comparison. This study compares the environmental impacts and benefits of different renovation and reconstruction scenarios of a social housing building in Ghent, Belgium, considering the entire building life cycle. The renovation scenarios differ in energy performance levels. While existing studies typically consider static average energy mix, this study performs an analysis to show the sensitivity of the results to the dynamics as well as the evolution of the electricity mix and marginal energy sources. The comparison between renovation and new construction shows a substantial decrease in environmental impact in new construction, with a reduction of up to 92% between analyzed scenarios, attributed to improved energy performance despite increased embodied impacts. Operational emissions remain a significant contributor to total impact across all scenarios, emphasizing the importance of electricity source composition. The findings underscore the effectiveness of more substantial renovation or reconstruction efforts over minimal adaptations, especially in meeting Belgium's environmental targets.

Cross-laminated timber (CLT) is increasingly proposed as a low-carbon alternative to steel or concrete in mid-rise multi-storey structures. In this study, the embodied carbon footprint of a CLT multi-storey building is analysed in a life cycle perspective, and strategies to optimise the carbon footprint are explored, based on CLT panel thickness optimisation and insulation material substitution. The analysis shows that the product and construction stage account for 72% of the life cycle embodied carbon footprint, and the effective post-use management of the materials arising from the end-of-life stage can give a significant climate benefit. A reduction of up to 5% of the life cycle carbon footprint can be achieved when employing the material optimisation and substitution strategies. This, together with effective post-use management of the building materials, results in a reduction of up to 20% of the life cycle carbon footprint of the studied CLT building. The study also emphasises the significance of service life in achieving a low carbon footprint for CLT buildings. Overall, this study shows that the life cycle embodied carbon footprint of a CLT building can be further reduced through material-related strategies.

A wider deployment of nearly zero energy buildings (NZEBs) is expected to contribute to the transition to a decarbonized and energy-efficient building sector in Europe. This study proposed an integrated energy-economic analysis to exemplify the feasibility of NZEB renovation in temperate climate. A parametric analysis was performed to identify technical building system configurations that give minimum share of renewable energy systems contributing to NZEB level. Final energy savings, global costs and cost-effectiveness of renovating a building to NZEB level are analysed, considering active and passive energy efficiency measures (EEMs). The active EEMs included efficient water taps and heat recovery ventilation, and the passive EEMs encompassed insulations to roof, exterior walls and ground floor, and improvements of windows and doors. The building had initial final energy use of 133 kWh/m2 year for space heating, domestic hot water production (DHW) and facility electricity. The results show that NZEB level is achieved with active and passive EEMs, without renewable energy systems for scenarios with low discount rates and high future energy price escalations. The annual final energy use for space heating, DHW and facility electricity is reduced cost-effectively by 37-54%. Furthermore, increasing size of PV-system enhanced cost-effectiveness by lowering total global costs.

This chapter discusses recent trends in management of postuse wood products and gives an overview of benefits and constraints associated with effective end-of-life management of wood. It highlights the implications of postuse wood management from resource efficiency and climate perspectives. Primary energy and GHG balances are important metrics to understand the resource efficiency of climate change mitigation strategies involving postuse wood products. The chapter describes mechanisms through which postuse management of recovered wood materials can affect primary energy use and GHG impacts of wood products. To further understand the implications of different postuse management options for wood products, we then explore several quantitative scenarios. There is potential for efficient management of postuse wood products by directing these resources to cascade uses including reuse, recycling, and energy recovery. This can offer significant opportunities to improve resource efficiency and reduce greenhouse gas emissions in the built environment.

There has been a growing interest in wood-based buildings in Europe in recent years. A reason for this is that sustainability issues are becoming increasingly important in the building and construction sector, which is responsible for around 40% of the total CO2 emissions and between 25-30% of the total waste discarded in landfills, worldwide. Previous studies have shown that linear economic practices regarding used wood in construction and discarding it with minimal reuse or recycling after the demolition of the building results in significant environmental impacts. Therefore, applying circular economy concepts and criteria in wood building construction seems vital. This article provides state-of-the-art literature review of circular economy and its implementation in wood multi-storey building construction. A systematic literature review is conducted in which relevant peer reviewed articles were retrieved and explored to identify the state-of-the-art and current knowledge gaps that require further research. From an initial set of 157 scientific papers, a set of 15 highly relevant papers were selected for in-depth examination. The visualization tool VOSViewer is used to identify and gather the relevant data and information from the following academic databases: Web of science, ScienceDirect and Google Scholar. This systematic review provides concepts, indicators and tools for circular economy and circular construction solutions for multi-storey wood building construction. It also highlights the key knowledge gaps that require further research. By addressing these issues, this study aims to contribute to promoting circularity in design, construction, use, and post-use phases of wood multi-storey buildings, which are urgently needed in the construction sector to mitigate climate change.