Estimation of energy demand and greenhouse gas emission reduction effect of cross-laminated timber (CLT) hybrid wall using life cycle assessment for urban residential planning

The building and construction sector accounted for 36% of final energy use and 37% of energy and process-related carbon dioxide (CO₂) emissions in 2020. According to a recent study, if the global population grows to 9.3 billion by 2050, new infrastructure development will cause approximately 350 Gt of CO₂ emissions, corresponding to 35–60% of the remaining carbon budget available up to 2050 if the average temperature increase is to be limited to 2 °C. Material substitution is one way to reduce embodied energy and CO₂ emissions. Cross-laminated timber (CLT), a bio-based material, can be an alternative to concrete and steel, which are the most energy- and carbon-intensive materials. However, there is a limit to the immediate application of CLT to the entire building. This study confirmed greenhouse gas (GHG) emission and energy consumption reductions when CLT was applied to the exterior walls of 52 apartment building types. Substituting CLT for concrete in the exterior walls resulted in a 44.6% savings in GHG emissions and 49.3% in energy demand. GHG emissions per floor were reduced by −16,906 kg CO₂-eq, while energy consumption per floor was reduced by −256,896 MJ. If CLT is used in 30% of the exterior walls of the 800,000 houses planned to be constructed in Seoul by 2030, the energy savings and GHG reduction effect are expected to be −11,495 TJ and −0.86 Mt CO₂-eq, respectively.