Construction Waste Reduction in Buildings through Modular and Offsite Construction

Construction waste causes severe environmental problems. Reducing construction waste generation becomes a major policy measure of governments to achieve sustainable development. Offsite construction approaches are effective for reducing onsite construction waste. Nevertheless, there is a lack of a clear understanding of the types and amounts of construction waste that different offsite construction approaches can reduce. This study aims to investigate the performance of the modular construction (MC) approach in construction waste generation and reduction and how it differs from that of the nonmodular offsite construction (NMOC) approaches by comparing 59 selected cases of building projects that adopt these offsite approaches compared with stick-built construction. Results indicated that the adoption of offsite construction contributed to significant onsite construction waste reduction. On average, adopting MC reduced 78.8% of overall construction waste, outperforming other construction approaches. The level of prefabrication influenced onsite construction waste generation and reduction the most, followed by the other properties like building typology, density, and material used. Seven knowledge gaps were identified in the area of waste identification, quantification, and assessment. The findings demonstrate the advantages of using offsite construction in waste control and management and add to the existing body of knowledge on onsite construction waste generation and on waste reduction through adopting MC. The identified knowledge gaps point directions of future research on waste reduction through offsite construction.