Life cycle impacts of structural deterioration and seismic events on cross-laminated timber buildings

Life cycle assessment (LCA) has become the preferred tool for evaluating the environmental impacts of buildings over their lifetime and informing infrastructure-related policy decisions. Traditionally, LCA is conducted using static inputs, which assume a building's current performance remains representative of its long-term carbon emissions. However, buildings naturally deteriorate over time-a factor particularly significant for timber structures-and this deterioration can be exacerbated by extreme natural hazards such as earthquakes. The associated repair or replacement activities introduce additional material and energy demands that influence environmental performance. This study introduces a stochastic approach to incorporate the environmental impacts associated with repair and replacement of timber buildings subjected to seismic hazards. The approach is comprehensive in nature, it accounts for the progressive structural deterioration of timber over time, demonstrating its substantial influence on structural performance and subsequent LCA results. The proposed framework is applied to a series of multi-storey cross-laminated timber (CLT) apartment buildings located in a seismically active region in Europe. Using nonlinear response history analyses (NRHAs) under multiple earthquake intensities, various structural deterioration rates are considered to assess their effects on building performance. A comparative LCA is conducted to analyse the contributions from both structural and non-structural damage, while also evaluating the impacts of design behaviour factors and number of storeys. Our findings highlight the importance of an integrated approach to incorporate long-term structural deterioration and seismic hazard impacts into LCA, providing a more realistic and dynamic assessment of timber buildings' environmental footprint over their lifecycle.