Advancing the circular economy and environmental sustainability with timber hybrid construction in South Korean public building: A case study

Timber is attracting attention as an alternative to conventional materials owing to the carbon sequestration effect during the growth process and the low carbon impact of timber use. Recently, carbon reduction, environmental impact reduction, and circular economy (CE) have been considered for sustainable development. There is a need to evaluate effective buildings in terms of CE and environmental impact, and timber has advantages in terms of circularity and environmental impact. However, few studies have quantified both environmental impact and circularity of timber buildings. In this study, environmental impact was introduced into the Building Circularity Indicators (BCI; a method of evaluating the circularity of materials and buildings). Then, the material circularity and environmental impact were verified through a timber hybrid case study of an actual public building using LCA and BCI. Environmental impact reductions of -13.5%, -11.5%, and -5.0% were achieved by the hybrid alternative that applied timber to the structure, the alternative that excluded the core, and the alternative that applied it only to the exterior wall, respectively. Furthermore, the BCI improved from 0.26 for the concrete structure to 0.31, 0.29, and 0.25, for the respective timber hybrid buildings mentioned above. The research results would aid designers and policymakers in their initial planning by verifying the realistically quantified environmental impact savings and circularity. In addition, as an example of introducing environmental impact into the BCI, it would contribute to the reduction of the disparity between the circularity indicators and environmental impact.