Search Results (71)

This paper presents LokAlp, a modular timber construction system invented and developed by the authors, inspired by the traditional Blockbau technique, and designed for circularity and self-construction. LokAlp utilizes standardized interlocking blocks fabricated from CLT and GLT off-cuts to optimize material reuse and minimize waste. The study explores the application of massive timber digital materials within an open modular system framework, offering an alternative to the prevailing focus on lightweight structural systems, which predominantly rely on primary engineered wood materials rather than reclaimed by-products. The research evaluates geometric adaptability, production feasibility, and on-site assembly efficiency within a computational design and digital fabrication workflow. The definition of the LokAlp system has gone through several iterations. A full-scale demonstrator constructed using the LokAlp final iteration (Mk. XII) incorporated topological enhancements, increasing connection variety and modular coherence. Comparative analyses of subtractive manufacturing via 6-axis robotic milling versus traditional CNC machining revealed a >45% reduction in cycle times with robotic methods, indicating significant potential for sustainable industrial fabrication; however, validation under operational conditions is still required. Augmented reality-assisted assembly improved accuracy and reduced cognitive load compared to traditional 2D documentation, enhancing construction speed. Overall, LokAlp demonstrates a viable circular and sustainable construction approach combining digital fabrication and modular design, warranting further research to integrate robotic workflows and structural optimization. Full article

This study provides a bibliometric analysis of life cycle assessments (LCAs) to explore the sustainability potential of mass timber buildings, focusing on glulam. The analysis highlights regional differences in carbon footprint performance within the ISO 14040 and EN 15978 frameworks. LCA results from representative countries across six continents show that wood buildings, compared to traditional materials, have a reduced carbon footprint. The geographical distribution of forest resources significantly influences the carbon footprint of glulam production. Europe and North America demonstrate optimal performance metrics (e.g., carbon sequestration), attributable to advanced technology and investment in long-term sustainable forest management. Our review research shows the lowest glulam carbon footprints (28–70% lower than traditional materials) due to clean energy and sustainable practices. In contrast, Asia and Africa exhibit systemic deficits, driven by resource scarcity, climatic stressors, and land-use pressures. South America and Oceania display transitional dynamics, with heterogeneous outcomes influenced by localized deforestation trends and conservation efficacy. Glulam buildings outperformed concrete and steel across 11–18 environmental categories, with carbon storage offsetting 30–47% of emissions and energy mixes cutting operational impacts by up to 67%. Circular strategies like recycling and prefabrication reduced end-of-life emissions by 12–29% and cut construction time and costs. Social benefits included job creation (e.g., 1 million in the EU) and improved well-being in wooden interiors. To further reduce carbon footprint disparities, this study emphasizes sustainable forest management, longer building lifespans, optimized energy mixes, shorter transport distances, advanced production technologies, and improved recycling systems. Additionally, the circular economy and social benefits of glulam buildings, such as reduced construction costs, value recovery, and job creation, are highlighted. In the future, prioritizing equitable partnerships and enhancing international exchanges of technical expertise will facilitate the adoption of sustainable practices in glulam buildings and advance decarbonization goals in the global building sector. Full article

The building sector significantly contributes to global energy consumption and carbon emissions, primarily due to the extensive use of carbon-intensive materials such as concrete and steel. Mass timber construction, particularly using cross-laminated timber (CLT), offers a promising low-carbon alternative. This study aims to calculate the embodied carbon emissions and biogenic carbon storage of a CLT-based affordable housing project, 340+ Dixwell in New Haven, Connecticut. This project was designed using a honeycomb structural system, where mass timber floors and roofs are supported by mass timber-bearing walls. The authors are not aware of a prior study that has evaluated the life cycle impacts of honeycomb mass timber construction while considering Timber Use Intensity (TUI). Unlike traditional post-and-beam systems, the honeycomb design uses nearly twice the amount of timber, resulting in higher carbon sequestration. This makes the study significant from a sustainability perspective. This study follows International Standard Organization (ISO) standards 14044, 21930, and 21931 and reports the results for both lifecycle stages A1–A3 and A1–A5. The analysis covers key building components, including the substructure, superstructure, and enclosure, with timber, concrete, metals, glass, and insulation as the materials assessed. Material quantities were extracted using Autodesk Revit^®, and the life cycle assessment (LCA) was evaluated using One Click LCA (2015)^®. The A1 to A3 stage results of this honeycomb building revealed that, compared to conventional mass timber housing structures such as Adohi Hall and Heartwood, it demonstrates the lowest embodiedf carbon emissions and the highest biogenic carbon storage per square foot. This outcome is largely influenced by its higher Timber Use Intensity (TUI). Similarly, the A1-A5 findings indicate that the embodied carbon emissions of this honeycomb construction are 40% lower than the median value for other multi-family residential buildings, as assessed using the Carbon Leadership Forum (CLF) Embodied Carbon Emissions Benchmark Study of various buildings. Moreover, the biogenic carbon storage per square foot of this building is 60% higher than the average biogenic carbon storage of reference mass timber construction types. Full article

Mass timber construction is gaining popularity in mid-rise and tall buildings due to its sustainability, aesthetics, versatile prefabrication, light weight, and faster construction time compared to conventional building materials such as concrete and steel. One of the challenges with timber construction is a potential fire hazard, and the risk is even aggravated in taller buildings due to the increased evacuation period. Several researchers have identified and reported important parameters that will have direct influence over mass timber fire performance behaviour. However, the current findings from the literature do not provide a correlation between the key parameters and the fire performance behaviour. This paper presents a review of experimental fire testing of mass timber structures and analyses the fire performance results output obtained from the experimental testing. This paper attempts to identify several key parameters that influence the fire performance behaviour of mass timber structures, such as peak temperature, charring rate and decay behaviour. The correlation between the key parameters and the fire performance behaviour of mass timber structures will enhance in developing a rational model to determine the time to reach the fire growth, peak temperature, charring behaviour, structural integrity (strength and stiffness reduction) and decay behaviour of the exposed timber. Full article

The construction sector’s increasing eco-consciousness is driving the need for higher-performance wood-based engineered products from underutilized timber resources, such as small-diameter trees from hazardous fuel treatments of our forests. Strand-based products, including oriented strand board (OSB) and lumber (OSL), are widely used. However, hot-pressing during their manufacturing generates approximately 10% waste, which includes a substantial amount of resinated strands that are landfilled. The huge potential of using strand-based products has led to many studies and growing interest in strand-based three-dimensional sandwich panels that can be used as wall, floor, or roofing panels. As the market grows, understanding the recyclability of these resinated strands becomes crucial. This study investigates the feasibility of using re-resinated waste strands that were collected during lab-scale production of strand-based panels. Results demonstrate significant improvements in dimensional stability, mechanical properties, and fire resistance. Specifically, recycling increased internal bond strength, flexural strength, time to ignition, time to flameout, mass loss, and time to peak heat release rate by 107%, 44%, 58%, 35%, 51%, and 27%, respectively, and helped decrease water absorption and thickness swell by 51% and 58%, respectively. Full article

Timber–concrete composite (TCC) floors are gaining popularity in sustainable construction due to their enhanced stiffness and structural efficiency. However, excessive vibrations, particularly those induced by human activity, pose significant challenges to occupant comfort and structural integrity. This study investigates the application of Tuned Mass Dampers (TMDs) to mitigate vibrations in TCC floors, with a focus on enhancing damping performance through the incorporation of pre-strained Shape Memory Alloys (SMAs) (Kellogg’s Research Labs, New Boston, NH, USA). A novel pre-strained SMA–TMD system was designed and experimentally tested to evaluate its effectiveness in vibration control under various loading conditions. The results demonstrate that pre-straining significantly increases the damping ratio of the SMA–TMD, improving its vibration mitigation capability. Compared to non-pre-strained SMA–TMD, the pre-strained SMA–TMD system exhibited superior adaptability and robustness in reducing floor vibrations, achieving a peak acceleration reduction of up to 49.91%. These findings provide valuable knowledge into the development of advanced damping solutions for timber floors, contributing to the broader application of vibration control strategies in sustainable and high-performance building systems. Full article

The urgent need for climate change mitigation has increased the focus on reducing embodied carbon and energy, particularly in the construction sector. Utilizing sustainably sourced mass timber products provides a low-carbon alternative to traditional concrete and steel structural systems in buildings. These carbon impacts can be quantified by evaluating the total environmental impact of a building, from material extraction and product manufacturing to construction, operation, and demolition. This study evaluated the environmental impacts of a 14-storey mass timber–steel hybrid building in Madison, USA, through a Whole-Building Life Cycle Assessment (WBLCA) using the Tally LCA tool integrated with Autodesk Revit. The hybrid design was compared to full mass timber, full steel, and post-tensioned concrete structures, which are common structural systems for high-rise buildings, enabling meaningful comparisons of their environmental performance. The results showed that the full mass timber design had the lowest global warming potential (GWP), reducing emissions by 16% compared to the concrete structure. The hybrid design achieved a 14% reduction, with both timber-based systems demonstrating about 30% lower non-renewable energy use. In addition, they provided significant biogenic carbon storage during the building’s lifespan. However, the mass timber and hybrid systems showed higher impacts in categories such as acidification, eutrophication, ozone depletion, and smog formation. Full article

The plastic profile of construction waste is varied and complex, particularly when compared to other waste streams such as timber, concrete, metals, and plasterboard. There are fewer incentives for recycling this low-density, low-value waste stream. Plastic waste generated by construction activities remains poorly characterised, obstructing efforts to optimise reduction, reuse, and recycling practices. To understand its types and sources, and better address plastic waste management, this study audited plastic waste produced across six new-build construction sites in Auckland, New Zealand. A total of 7.2 tonnes of plastic construction waste was collected on-site and audited. Plastics were separated, weighed, and categorised by function and construction stage. Polymer type was determined using Fourier transform infrared (FTIR) spectroscopy. In total, 62% of plastic waste was diverted from landfill through reuse or recycling. On average, 0.61 kg of plastic was generated per m² of construction. Soft plastics were the most generated by mass (33%), followed by PVC and HDPE pipes (22%), shrink wrap (12%), and expanded polystyrene (5%). The majority of plastic waste was generated in the final stages of the projects. The authors recommend the separation of soft plastic, pipes, shrink wrap, and polystyrene on construction sites, particularly towards the finishing stages of construction. Full article

The increase in population and urban migration has incentivized the construction of mid-rise and tall buildings. Despite the incremental rise in vertical construction, there are still investigation gaps related to high-rise buildings, such as carbon emissions and the use of low-carbon materials in tall structures. Timber presents a potential sustainable solution for mid-rise and tall buildings. The history of topics in timber building investigations began with the material characterization of innovation in construction technologies such as cross-laminated timber (CLT) and practical topics like construction collaboration, sustainability, engineering, and construction science. To identify potential topics and understand the research history of mid- and high-rise timber buildings, a bibliometric analysis is proposed. Therefore, this article aims to perform a bibliometric analysis with a science mapping technique to categorize and analyze the evolution of mid- and high-rise timber building research topics and identify the most relevant trends and current challenges. A co-occurrence keyword analysis was performed with the software SciMAT to analyze the evolution and actual trends of mid-rise and tall timber buildings. The results show an evolution in the investigation topics from timber frame elements to mass timber and CLT for high-rise buildings, which was expected due to the higher structural capacity of the mass timber product. Surprisingly, sustainability topics such as carbon emission and life-cycle analysis (LCA) were transversal in all periods with concrete as a recurrent keyword in the analysis. More specialized topics such as robustness, disproportioned collapse, perceptions, and attitude were observed in the final periods. Research projections indicate that for mid-rise and tall timber buildings, the environmental potential has to be aligned with the structural feasibility and perception of the construction’s actors and society to improve the carbon emissions reduction and support the increment of the population in an urban context. Full article

In timber construction, Glulam post-and-beam systems are commonly used to transfer vertical loads to the foundation. In such systems, the connections play a critical role in structural performance. Pre-engineered connectors, which facilitate fast and efficient assembly, are typically designed to resist only vertical shear loads. However, during seismic and wind events, post-and-beam systems deform horizontally, and axial forces develop at the connections. In this research, the performance of RICON and MEGANT pre-engineered connectors was studied under biaxial loading involving concurrent shear and axial forces. A total of 12 full-scale tests on Glulam frame segments were conducted. Neither type of connector experienced any resistance loss under concurrent shear loads equal to the factored shear resistance and axial loads equal to 5% of the factored shear resistance. The axial load-carrying capacity of the RICON and MEGANT connectors was up to 124% and 97% of their factored shear resistance, respectively. The global failure of all the studied connectors demonstrated both ductility and residual deformation capacity. These results provide valuable information for engineers designing Glulam post-and-beam systems in seismic regions. Full article

In contemporary building design, partition walls combined with doors and windows are commonly used to control the spread of smoke. Understanding the smoke leakage characteristics of cross-laminated timber (CLT) walls is crucial for enhancing safety. This study investigates the smoke-sealing performance of CLT walls through full-scale tests, focusing on the application of this type of mass timber construction in smoke control. The test specimens included four joints, with leakage measured under two conditions—non-fire and fire exposure—at three different pressure differentials. A total of 72 tests were conducted. The results showed that under non-fire conditions, the leakage rate was 0.00 m³/h, while exposure to fire caused a significant increase in leakage. Under a pressure differential of 25 Pa, the average leakage rate was 8.17 m³/h, with a maximum of 8.27 m³/h. This study also proposes a method for evaluating the leakage rate of a single joint, which helps estimate the smoke layer descent time and, in turn, the allowable evacuation time. The findings not only enhance the fire safety performance of mass timber construction but also provide valuable insights for evacuation planning. Full article

Mass timber is increasingly being employed in constructing low- and mid-rise buildings. One of the primary reasons for using mass timber structures is their sustainability and ability to reduce environmental consequences in the building sector. One criticism of these structures is their lower subjective sound insulation quality. Therefore, acoustic treatments should be considered. However, acoustic solutions do not necessarily contribute to lower environmental impacts or improved thermal insulation performance. This paper discusses a design methodology that incorporates the development of a sound insulation prediction tool (using an artificial neural networks approach), life cycle assessment analysis, and thermal insulation study. A total of 112 sound insulation measurements (in one-third octave bands from 50 to 5000 Hz) are utilized to develop the network model and are also used for the LCA and thermal insulation study. They are lab-based measurements and are performed on 45 various CLT- and ribbed CLT-based assemblies. The acoustic model demonstrates satisfactory results with 1 dB differences in the prediction of airborne and impact sound indices ($R_w$ and $L_{n,w}$). An acoustic sensitivity study and a statistical analysis are then conducted to validate the model’s results. Additionally, an LCA analysis is performed on the floor assemblies to calculate their environmental footprints. LCA categories are plotted against the acoustic performance of floors. No correlations are found, and the results emphasize that a wide range of sound insulation can be achieved with similar environmental impacts. Within each acoustic performance tier, the LCA results can be optimized for a floor assembly by selecting appropriate materials. The thermal insulation of floors is then calculated. Overall, a strong positive correlation is found between the total thermal resistance and heat loss against acoustic performance. Designers should be cognizant of the trade-offs between acoustic, thermal insulation, and environmental performance when choosing assemblies with favorable environmental impacts relative to acoustic and thermal insulation ratios. Full article

Massive construction systems have always characterized traditional architecture and are currently the most prevalent, straightforward, and cost-effective in many Mediterranean countries. However, in recent years, the construction industry has gradually shifted towards using lightweight, dry construction techniques. This study aims to assess the effects on energy consumption, comfort levels, and environmental sustainability resulting from the adoption of five high-performance construction systems in a multi-family residential building: (i) reinforced concrete structure with low-transmittance thermal block infill; (ii) reinforced concrete structure with light-clay bricks and outer thermal insulation; (iii) steel frame; (iv) cross-laminated timber (CLT); (v) timber-steel hybrid structure. To achieve this goal, a multidisciplinary approach was employed, including the analysis of thermal parameters, the evaluation of indoor comfort through the adaptive model and Fanger’s PMV, and the quantification of environmental and economic impacts through life cycle assessment and life cycle cost applied in a long-term analysis (ranging from 30 to 100 years). The results highlight that heavyweight construction systems are the most effective in terms of comfort, cost, and long-term environmental impact (100 years), while lightweight construction systems generally have higher construction costs, provide lower short-term environmental impacts (30 years), and offer intermediate comfort depending on the thermal mass. Full article

The building and construction industry is one of the largest greenhouse gas producers, accounting for 39% of global emissions, most of these coming from concrete and steel. Mass timber construction (MTC) potentially offers a sustainable alternative to these traditional building materials. However, more research is needed to establish the sustainability credentials of MTC relative to traditional concrete and steel structures, especially for mid-rise structures. The aim of this study is to evaluate the environmental and cost performance of mid-rise mass timber buildings by conducting a life cycle assessment (LCA). The LCA uses a cradle-to-cradle approach, considering the global warming potential (GWP), freshwater use (FW), and total use of non-renewable primary energy resources (PENRT). Results indicated that mid-rise mass timber buildings have significantly lower impacts than concrete buildings, with their GWP approximately 30 times lower, FW about 20 times lower, and PENRT reaching a negative value. Additionally, the cost analysis revealed that MTC buildings can be cheaper to build and thus possibly more profitable than concrete buildings. These findings establish mass timber as a viable and sustainable option for the future of Australia’s construction industry. Full article

Mass timber construction has recently gained popularity due to its outstanding environmental benefits and building performance, which hold revolutionary potential for the construction industry. However, its impacts from the perspective of occupants have not been thoroughly explored. This study introduces an innovative empirical approach that explores the potential benefits of mass timber construction for individuals and organizations, with an emphasis on the workplace. We review the conceptual framework regarding how visual and physical exposure to timber construction materials and finishes have a positive effect on individuals and organizations at a broad level. We propose a more holistic mixed-method behavioral approach to studying occupant behavior and well-being by integrating self-reported questionnaires, objective biomarkers (heart rate variability and hair cortisol), and indoor environmental quality (IEQ) measures. Our study offers a novel research primer on the exploration of mass timber construction impacts and benefits for both office workers and construction workers. Participants from different office settings completed pre- and post-occupancy evaluation surveys to assess their experiences, including IEQ satisfaction, productivity, and health. Office workers were located in three different offices: a controlled laboratory environment, an open-plan office, and an open-plan space with a timber interior. The construction workers worked in a timber space for three months and then moved to work in a building with a concrete structure. The analysis included descriptive statistics, t-tests, ANOVA, and linear regression to compare differences between office settings and assess the relationship between environmental variables and overall satisfaction in IEQ, comfort, productivity, and health. In office workers, in terms of building image, thermal comfort, and artificial lighting, the data analysis revealed significant differences in occupants’ satisfaction levels between office settings. However, the low number of participants affected the results, and some factors were not found significant in relation to the office setting. Among tradespeople, there was no relationship between the building environment and productivity, health, or comfort. However, the results of hair cortisol testing indicated that working in a timber space can decrease the level of cortisol (stress) and have an impact on the productivity of workers. Such occupant’s perspective research is pivotal to informing policy makers, developers, business owners, construction professionals, timber industry stakeholders, environmentalists, and researchers in their decision-making processes. Fostering the future widespread adoption and advancement of mass timber construction. Full article