Group technology empowering optimization of mixed-flow precast production in off-site construction

Abstract

Faced with immense pressure to reduce carbon emissions, off-site construction (OSC) is considered as a sustainable alternative from conventional practices. However, challenged by component diversity and a sharp rise in demand, deficient management in off-site precast production struggles to effectively tackle real-world challenges of component grouping, coupled with insufficient attention to environmental impacts, ultimately resulting in falling short of expected benefits in OSC projects. Therefore, this study discusses carbon emissions and component grouping issues in off-site precast production. A multi-objective optimization framework is proposed, aiming to minimize carbon emissions and reduce tardiness/ earliness penalty while considering the incorporation of grouping technology for component grouping.The non-dominated sorting genetic algorithm II (NSGA-II), adjusted by adaptive population initialization strategy and group technology, is introduced for solving this problem, striking a balance between sustainability and penalty costs.Through a real-case analysis, the proposed approach demonstrates an average reduction of 37.5% in carbon emissions compared to rule-based scheduling methods, a 30.1% reduction compared to previous research methods, along with over 10% reduction in tardiness/ earliness penalty. This study enhances carbon efficiency from a production scheduling perspective and establishes an automated, practical method, fostering low-cost, high-efficiency green production for construction component enterprises, particularly for small and medium-sized enterprises, thereby promoting sustainable development in the construction industry.