Evaluating the carbon emissions of Hong Kong's building sector from the life cycle perspective

The building sector is a typical end-use sector that involves multiple stages associated with carbon emissions (CE). Accurately quantifying the CE of the building sector from the life cycle perspective can establish a foundation for its decarbonisation. This study focuses on Hong Kong to develop a six-stage CE calculation methodology with the process-based life cycle assessment framework. Specifically, the datasets of newly-constructed buildings are analysed to classify the buildings into 11 archetypes. Furthermore, the logarithmic mean Divisia index is used to identify the primary driving factors of the CE. Results show that the CE of Hong Kong's building sector ranged from 34.75 to 40.23 Mt per annum during the ten-year period 2012-2021. Electricity consumption accounted for over 90 % of the operational CE, while the production of major building materials, such as steel, cement, and aluminium, took up over 80 % of the embodied CE. Moreover, energy efficiency and CE efficiency factors were revealed to impose significant impacts on CE decrease by 1.94 and 1.68 Mt cumulatively in 2012-2021, whereas the population factor was found to increase the CE by 1.43 Mt. The findings should inform Hong Kong building sector's decarbonisation plan, and the study provides an innovative approach for tracking the climate change impacts of building sectors in cities.