More than 20% of global carbon emissions are linked with the production of construction materials used in the built environment. The use of bio-materials along with urban densification strategies that avoid demolition and reduce material demand, have been recommended to achieve urban sustainability goals. Addressing these measures, this study compares the life cycle embodied carbon emissions of seven hybrid top-up structural systems composed of concrete, steel and advanced engineered timber products made out of softwood and hardwood species. The life cycle carbon emissions (expressed in kgCO2-eq) were estimated following a cradle-to-grave approach, with a functional unit equivalent to 1 m2 of top-up structural system and focusing on The Netherlands and the city of Amsterdam as main geographical scope. A statistical analysis was included to account for the potential variation of emissions across each life cycle stage, using Monte Carlo simulations for random sampling. The results indicate that predominantly bio-based structures present a staggering 60% lower embodied carbon emissions compared with predominantly concrete, steel and modestly hybrid systems. Preserving the long-term carbon storage capacity of timber elements through high-quality reuse can offset 30–60% of the total positive emissions of the predominantly bio-based systems. Up to 6MtCO2-eq of the national carbon budget in The Netherlands can be saved from a radical uptake of bio-based structures in Amsterdam by 2050. Diversification of material diets with bio-based alternatives is recommended, along with established policy that can guarantee sustainable sourcing and prolonged lifespans through high-end reuse practices.@en

From a global perspective, the building industry stands as a significant factor of environmental impact on the planet. Wood has emerged as a promising construction material as a sustainable building source, gaining traction in the industry due to its carbon storage capabilities and prefabricated possibilities [13]. Particularly in the context of rural Colombia, the integration of prefabricated timber constructions, coupled with advancements in digital fabrication technologies, holds the promise of facilitating social reconstruction. Furthermore, such an approach poses the potential to enhance material performance and contribute positively to its end of life [1].

Nevertheless, existing research identifies a critical gap within the wood-to-wood timber connections to tackle better design, manufacture, assembly, and deconstruction (DfMA + D) [20]. Consequently, this study endeavours to explore the application of Computer Numerical Control (CNC) technologies in conjunction with the material's response to changes in relative humidity. The aim is to devise a mechanism for tight-fitting structural wood connections, the central focus of this research lies in understanding the collaborative interaction between sawn timber and moisture fluctuations. By doing so, the study seeks to introduce a new construction methodology and building system centred around material climate reaction and its expansion capacity applications in traditional connections, thereby mitigating the need for chemical and mechanical structural joints, ultimately resulting in a self-assembly system destined to low-income populations in the Colombian territory. This study proves the enhancement of timber connection to tensile stress up to 50% of its original capacity by implementing the moisture induced process and developing a building system utilising this joining method for the assembly of elements for housing in Colombia.@en