Holistic life-cycle accounting of carbon emissions of prefabricated buildings using LCA and BIM

Abstract

Prefabricated concrete building (PCB) can save resources, reduce construction, improve quality, and reduce pollution. Understanding PCB environmental benefits versus traditional buildings could reinforce relevant policies and adoption. This study aimed to develop a holistic life-cycle accounting system based on BIM technology to calculate carbon emissions of PCB accurately and efficiently, and verify the effects of energy saving and emission reduction. Existing international and national databanks allowed the compilation of carbon emission factors. Five representative residential PCB projects were enlisted to calculate carbon footprints in six individual life-cycle construction stages. In most stages, carbon emissions were reduced with an increasing prefabrication rate. In the operation and maintenance stage, carbon emissions accounted for approximately 91% of the total, and the building materials production stage accounted for about 11%. The “negative carbon emission” in the demolition and recycling stage was about −4%. Carbon emissions of the remaining three stages were minimal at about < 2%. This study established the whole life-cycle carbon-emission indices of residential prefabricated buildings, with average annual carbon emission per unit area at around 105.88 kgCO2/(m2.a), and computed values for individual building stages. For comparison, a completely cast-in-place building was studied, with average annual carbon emission per unit area at around 130.79 kgCO2/(m2.a), significantly higher than the PCB. The study contributed to knowledge by furnishing the holistic carbon footprint calculation method and establishing the empirical patterns and trends of carbon emissions of PCB. The findings could inform construction projects' carbon-emission control and achieve the construction industry's green and low-carbon goals.