Improved framework for estimating carbon emissions from prefabricated buildings during the construction stage: Life cycle assessment and case study

The construction industry is a significant contributor to global greenhouse gas emissions, with the architecture, engineering, and construction (AEC) sector accounting for more than one-third of these emissions. Prefabricated buildings, known for their efficiency and reduced on-site waste, offer a promising avenue for mitigating the environmental impact. However, the consistent estimation of carbon emissions during the construction phase, specifically considering comprehensive factors for the embodied carbon, remains challenging. This study presents an improved framework for estimating carbon emissions from prefabricated buildings using life cycle assessment (LCA). The framework focuses on embodied carbon, which encompasses emissions from building materials production, transportation, and construction processes. The research identifies key sources of embodied carbon, including materials, machinery, transportation, and labor. It proposes a new estimation method that comprehensively considers factors such as load rates, human energy consumption, and construction delays. Through a detailed case study of a three-story teaching building in China, the study demonstrates the application of the proposed framework. The results highlight that embodied carbon, mainly from material production, constitutes most of the total carbon emissions during construction. In addition, the embodied carbon emissions from transportation and labor also exceed 10 tons, which cannot be ignored. The study's findings emphasize the need for a comprehensive approach to carbon management in the construction industry, advocating for sustainable practices in material production and optimized construction processes.