Timber-based Façades with Different Connections and Claddings: Assessing Materials’ Reusability, Water Use and Global Warming Potential

Abstract

Timber-based façade technologies have the potential to effectively reduce the carbon footprint, reduce water use in construction, and minimize waste, when their manufacturing process is highly prefabricated. Additionally, avoiding glue parts can enhance the sustainability of the façade as its elements can be replaced (extending the durability of façades and therefore buildings) and separated once that they reach their end of life (to re-use or recycle them). Thus, the connection between materials might have a considerable impact on the façade’s sustainability. Moreover, timber-based façades can have different claddings, impacting on the water needed for the technology and their Global Warming Potential (GWP). This paper assesses, through a novel methodological approach, materials’ reusability, water use, and GWP for different façade connections and claddings. Four prototypes with different connections (staples, screws, timber nails, and geometrical assembly) were built. Experimental activities representing façade elements’ substitution and disassembly provided qualitative and quantitative information about production, extraordinary maintenance, and end-of-life phases. Through these tests, the quantity of material that could be re-used and disposed in such phases was quantified and then inserted in a Life Cycle Analysis (LCA). LCA was conducted using EF v.3.0 impact method and components were modelled with EPD information and Ecoinvent cut-off 3.7 database. According to the results, a timber-based façade with timber nails and wood cladding is the most promising of reusable façade materials, decreasing the water use and GWP.

Assessing the circular re-design of prefabricated building envelope elements for carbon neutral renovation

“…This study revealed that, compared to the baseline, an increase in disassembly potential of up to 100% can be achieved for an end-of-life scenario reusing the building envelope element at large and an increase of up to 49% on the level of materials and components being applied. In line with previous research (Juaristi et al, 2022), this research, therefore, advocates that, based on a careful design process and within the framework of existing product certification, it is possible to substantially increase future reuse potential contributing to improved material efficiency in the construction sector.…”

“…However, beyond efficiency gains, the full potential of prefab façade elements has not yet been met, and substantial improvements can be achieved to improve the level of sustainability, circularity, and customization in a way that does not increase project risks, complexity, and building costs of renovation projects (Juaristi et al, 2022;Lam et al, 2022). The level of circularity of prefab façade elements can be substantially improved by facilitating access to individual components of the product system, thereby facilitating refurbishing, reuse, and recycling (Chung et al, 2014;Kimura et al, 2001;Ma & Kremer, 2016;Okudan Kremer et al, 2013).…”

“…This is especially relevant for components that age more rapidly than parts they interface with or that improve faster, for example, due to higher innovation clock speeds, leading to an opportunity for modular upgrades of the system. As indicated by previous studies, the two most prominent indicators to take into consideration are the design for disassembly index and embodied carbon to subsequently assess the potential to replace, reclaim, and reuse valuable construction materials and reduce the overall environmental footprint (Juaristi et al, 2022;Bitar et al, 2022).…”

“…Their key finding was that a substantial LCEP is possible close to 100% for a zero-energy building retrofit with circular prefabricated building elements. In a comparative study, Juaristi et al, (2022) showcased that timber-based façades have the potential to substantially reduce the carbon footprint relative to façades constructed with inorganic construction materials (Hildebrand, 2014). Moreover, these authors calculated that the carbon footprint can be further reduced if components are reused in a second life cycle depending on the careful selection and design of construction materials and connections.…”

“…This particularly calls for empirical studies validating 'systemic' frameworks assessing circularity in the construction industry (Attia and Al-Obaidy, 2021;Lam et al, 2022). Juaristi et al, (2022) further suggest that future works should be on the effect of ageing on reclaiming and reusing construction materials and its impact on efficient material usage, waste, and environmental footprint. This article, therefore, attempts to contribute by answering the following research question: Assuming the current system conditions, i.e.…”