Analysis of interrelationships between critical waste factors in office building retrofit projects using interpretive structural modelling

The number of office building retrofit projects is increasing. These projects are characterized by processes that have a close relationship with waste generation and therefore demand a high level of waste management. In a preliminary study reported separately, we identified seven critical factors of on-site waste generation in office building retrofit projects. Through semi-structured interviews and interpretive structural modelling method, this research further investigates the interrelationships among these critical waste factors, identifies each factor's level of influence on waste generation and proposes effective solutions for waste minimization. 'Organizational commitment' was identified as the fundamental issue for waste generation in the ISM system. Factors related to plan, design and construction processes were found to be located in the middle levels of the ISM model but still had significant impacts on the system as a whole. Based on the interview findings and ISM analysis results, some practical solutions have been proposed for waste minimization in building retrofit projects: (1) reusable and adaptable fit-out design, (2) a system for as-built drawings and building information, (3) integrated planning for retrofitting work process and waste management and (4) waste benchmarking development for retrofit projects. This research will provide a better understanding of waste issues associated with building retrofit projects and facilitate enhanced waste minimization.