Developing a tier-hybrid uncertainty analysis approach for lifecycle impact assessment of a typical high-rise residential building

Abstract Reducing embodied impacts of buildings has become urgent given its dramatically increasing contribution to the total lifecycle impact. The embodied impact is traditionally assessed through a deterministic lifecycle assessment (LCA) approach whose validity is impaired by existing uncertainties in the building lifecycle, so that uncertainty analyses are necessary to improve the validity of buildings LCAs. However, there are many limitations in current uncertainty studies such as biases in the use of a pure data quality indicator (DQI) approach, a lack of uncertainty analyses for lifecycle phases such as the end-of-life stage, and the incomprehensiveness in uncertainty parameters. To address these gaps, this study: (i) proposed a tier-hybrid uncertainty assessment approach to evaluate parameter uncertainties in the lifecycle of buildings; (ii) adopted proper assumptions to explore the impact of scenario and model uncertainties as well as investigate strategies to reduce the energy use and carbon emission. A case study is conducted to estimate uncertainties in building LCAs where end-of-life management strategies and alternative design materials are comprehensively explored to reduce energy and environmental impacts. It is revealed that the materials production stage causes the least uncertainties although it contributes the most impacts. Uncertainties in other lifecycle phases reduce in the order of transportation, maintenance to construction. Also, it is proved that the alternative design strategies and materials explored can effectively reduce the energy use and carbon emission by 19.91% and 15.23%, respectively. Therefore, the developed tier-hybrid approach can increase the comprehensiveness and reliability of building LCAs.