The massive environmental impacts of the construction industry due to its resource dependency and consumption, emissions, and waste generation cannot be neglected. Implementing the circular economy concepts is recognised as the main solution to the transition of this industry to a more sustainable one. While timber is considered as one of the sustainable construction materials, increased use and demand for timber lead to increased volumes of wood processing residues. In this study, state-of-the-art structural flooring elements that are made of a combination of industrial wood residues in the form of ungraded offcuts and graded timber are investigated. The flooring systems are designed for easier disassembly and circular use in the future. Uncertainties exist regarding these elements’ mechanical properties and expected service life. This research investigated the impact of using industrial wood residues on the long-term service life of these developed systems. Regression models were used to predict the flooring systems’ creep factor and deflection values at long periods in their future life cycles. The results of the long-term bending test are presented to ensure decisions on the long-term and extended service life of state-of-the-art flooring elements. The results highlight the possibility of defining new end-of-life scenarios for both industrial wood residues and flooring systems, ensuring the long-term quality of these systems based on long-term service life assessments. This can increase the utilization rate of industrial wood residues in high-quality structural systems, leading to an increase in the carbon storage time and contributing to the existing net-zero emissions strategies

Background and aim. Developing timber buildings suitable for deconstruction, reuse, and adaptability in practice is challenging and complex. The project “Design for the Future - Reuse of Timber Buildings in a Circular Economy” developed two concept buildings to be reused with preserved functionality. Focus was on environmental benefits and was obtained through collaboration within the circular value chain and according to real estate developers’ requirements. One building featured industrially manufactured volumes designed to be relocated and rebuilt. The other was an adaptable building with planar elements, designed to be flexible, relocated and vertically extended with two added floors. Methods and Data. The concept method, a co-creation process, was used that involved possible scenarios, construction, deconstruction, reconstruction, waste management and estimation of reusability. The method SimFORCE, Simulation for Future Oriented Reuse and Circular Economy, was developed. Evaluation of reusability and preserved functionality was conducted in cooperation with expert groups. The climate reduction potential of reuse was analysed using Life Cycle Assessments. Findings. SimFORCE helps identify whether structures are designed for deconstruction or need improvement. Further, the results were useful in preparing and writing deconstruction and reconstruction guides. Climate calculations show a significant reduction in environmental impact when buildings are reused. Theoretical/Practical/Societal Implications. With SimFORCE, two timber buildings were demonstrated as possibly being reusable with preserved functionality (structural, acoustics, fire resistance, etc.) with a considerably reduced climate impact. Assessments were based on profound knowledge and experiences of the building systems, deconstruction and testing. The actual buildings have not been deconstructed and rebuilt.

Cross-laminated timber (CLT) is increasingly used in sustainable construction but is sensitive to moisture, which can compromise durability and promote microbial growth. Damage to temporary weather protection during construction can lead to unintended moisture exposure. In such cases, it is important to understand how the material may have been affected. While X-ray computed tomography (CT) is not suitable for field application, it offers a detailed means of studying internal moisture behaviour and contributes to a better understanding of moisture-related risks in CLT following barrier failure.This study uses CT to investigate how moisture distributes and changes within CLT after protective covering damage. Eight CLT specimens from Scots pine were subjected to controlled wetting and drying cycles. Time-resolved CT scanning, combined with image processing techniques, was used to capture internal moisture variation with high spatial resolution. The method enabled detailed observation of both absorption and drying, revealing transport patterns between layers and interfaces.The study demonstrates that CT effectively reveals both moisture spread and slow drying in CLT following barrier failure.

Background and aim. Considering the significant amount of timber constructions that end up in landfills or are incinerated, promoting efficient and circular use is essential. Designing structural elements for dis- and reassembly can extend their lifespan. However, uncertainties remain about these elements' material properties and functional performance after being disassembled, and whether they meet technical requirements for structural building products. This study investigates the impacts of using industrial wood residues to produce I-beams and multiple disassembly cycles on the mechanical properties of floor elements. Methods and Data. The E-modulus and bending strength of elements were measured with bending tests performed according to EN 408:2010. The effects of dis- and reassembly on flooring elements made from a combination of graded sawn timber and industrial wood residues in the form of ungraded sawn timber offcuts were tested and evaluated after repeated cycles and compared to reference values. Initially, six elements were disassembled once or twice, and three elements were tested until failure to be considered as reference elements. Findings. Two different types of reassembly processes were considered for the elements. The first reassembly type resulted in a decrease in both bending strength and E-modulus mean values. In contrast, the second reassembly type led to an approximately 78% increase in bending strength and a slight 9% decrease in E-modulus. Theoretical / Practical / Societal implications. Using industrial wood residues in the form of ungraded sawn timber offcuts and graded sawn timber to produce load-bearing systems increases industrial wood residue utilization in structural elements. Studying the mechanical properties of elements after one or two dis- and reassembly processes ensures the user of the quality of elements after disassembly and increases the reuse rate and carbon storage time. The study shows that new end-of-life scenarios can be defined for flooring elements and industrial wood residues.

Hur kan träindustrin bidra till ökad cirkularitet och samverkan i byggandets värdekedja? Övergången från en linjär ekonomi till en cirkulär ekonomi innebär utmaningar och det är svårt att veta var man ska börja. Kan industriellt producerade trähus ge svaret på hur en sådan process kan se ut och visa hur vi kan bygga idag för att återbruka mer i framtiden och därmed spara på planetens resurser?

Mapping of biogenic carbon flows in the forest-based value chains in Sweden

The sawmill and wood industry sector is characterized by a high proportion of the use of domestic raw materials, where only around 2% of the timber comes from imports. 2950 kt of carbon is exported, which can be compared to the domestic use (including for energy purposes) of 8720 kt of carbon. Of the primary raw material used in the sawmills, 28% ends up in sawn spruce (2280 kt of carbon) and 18% in sawn pine (1460 kt of carbon). The sawn timber is then sent to the construction trade or for further processing within the wood manufacturing industry into various construction products, as well as to the furniture industry. The remaining portion of the wood raw material in the sawmills becomes by-products that go to energy production or to the pulp and paper industry.

From the Swedish wood manufacturing industry, there is a flow consisting of by- and residual streams where the majority becomes return wood chips (RT chips) that are either burned in their own boilers for heat production at the industry or sent to heating or combined heat and power plants. The amount of RT chips that enter the Swedish power and heating plants annually amounts to 1300 kt of carbon. The difference between what goes into the wood manufacturing industry and what is energy recovered in the form of primarily RT chips is bound in long-lived products such as wooden frames, building interiors, furnishings, and furniture, which are also partially exported.

The market for reuse and recycling of wood within the construction sector is still underdeveloped in Sweden, pilot studies are ongoing, and only small amounts of timber flow in this process. Since construction products often have functional and quality requirements that need to meet current building codes upon reuse, reuse is complicated, and the issue of responsibility also complicates matters. Regulations, test methods, new actors, and business models need to be developed.

There is a clear potential to use by- and residual streams from the wood value chain more efficiently considering the increasing competition for wood raw material from the forest. Two clear tracks

• Capture juvenile fibers from the breakdown and postprocessing processes in the wood value chain and coordinate flows into volumes that can be utilized for products instead of energy production. This requires coordination of more sectors than just the actors in the forest sector to find the right biogenic raw materials for energy production.

• Develop processes, methods, and business models that contribute to RT chips being used to a greater extent for products instead of energy production. A prerequisite for change is that both industry and society's energy supply (electricity and heat) can be managed with less energy from combustion of wood raw material.

Among the actors in the value chain, there is an understanding and even a willingness to make a transition, but above all, there is a lack of economic incentives to do so.

A further perspective, given the increasing competition for wood raw material from the forest, is to reflect on the volumes of exported wood, its use, resource efficiency and possible national need.

Today, there is a significant lack of detailed public statistics and data on the amount of sawn timber that goes into various types of products. The risk of disclosing company- that data collected by, for example, SCB (Statistics Sweden) cannot be published officially. Not all companies report data either. Statistics are available for flows upstream for sawmill production and downstream for distribution. Individual companies in the value chain have good knowledge of their internal flows. Statistics for product categories within wood manufacturing are specified at the product level and not in the level of detail for the input material. The low resolution makes it difficult to compile reliable statistics for flows of wood-based material. For energy and heat production, statistics are available via Energiföretagen (Swedish Energy Companies) and industry organizations. However, there is currently poor knowledge about the material flows that go to RT chips, which then go to combustion. A further perspective, given the increasing competition for wood raw material from the forest, is to reflect on the volumes of exported wood, its use, resource efficiency and possible national need.

När en byggnad rivs skickas det mesta av virket till förbränning och energiåtervinning. Tänk om det i stället är möjligt både tekniskt och ekonomist att använda en del av virket för att industriellt tillverka fasader av återvunnet trä till nya hus! Tillsammans undersöker branschen och forskare möjligheterna för att använda återvunnet trä på ett lönsamt sätt.

The implementation of computer design within the building industry has created new possibilities for creating digital tools for users such as architects. There is however a lack of easy to use, efficient digital tools to aid and explore design alternatives for architects when using products within the wood building industry. This paper demonstrates how a modular facade system in wood can be adapted for facade configurations in different contexts by using computational design. The goal is to develop a digital design tool that is easy to use and provides the architect with a high degree of freedom to create project-unique facades. The design tool is developed with computational design methods for flexible and adaptive design. In parallel, assessment is made that the design solutions can be manufactured smoothly and quickly via digitalization and industrial production. The result of this research shows that the façade system can be customized by using parametric programming methods, and thus enable architects to design facades for different contexts. The design tool was verified with the architect partners concerning usability and manufacturers concerning production.

Hur kommer framtidens byggande att se ut? Forskningsinstitutet RISE och IVL Svenska miljöinstitutet genomför tillsammans med industriparter ett projekt för att studera återanvändning av träbyggnader i en cirkulär ekonomi. Projektparterna har bland annat arbetat med två demonstratorer där trähus ska kunna ändras, flyttas och byggas på efter behov.

There is a need for a shift towards circular economy in the building and construction sector. Design for deconstruction and reuse (DfDR) and design for adaptability (DfA) have been suggested as means to facilitate reuse of buildings and diminish waste and material consumption. A standard, ISO 20887:2020, has appeared to support the implementation of DfDR/A. One objective of this study is to demonstrate timber building design examples that can be considered consistent with the standard and designs that should be avoided. Another objective is to examine if there are important aspects of DfDR/A for timber buildings that are insufficiently covered by ISO 20887:2020. The broader, long-term aim of the work is to remove thresholds to DfDR/A by providing support for designers and industry in applying the standard. The principles and strategies in ISO 20887:2020 are illustrated with practical examples from case studies, organised in a searchable database.