Achieving Sustainable Construction Through Construction & Demolition Waste Minimisation in Residential Building Projects
Human desires and their fulfilment through urbanisation have become a global environmental concern. In addition, the factual claims made on socio-economic and environmental benefits achieved through Construction & Demolition (C&D) waste minimisation, are yet to be fully explored. This research sought to find out the contribution of C&D waste minimisation, to Sustainable Construction. Worldwide, the Construction Industry (CI) is considered as an instrument for economic growth and employment. As an industry, construction accounted directly for 6% of global GDP. In New Zealand (NZ) the building and construction sector contribute 7% to the nation’s GDP. Further, the residential sector in NZ contributed up to half of the total construction value. The NZ CI is in a period of growth and expected to remain a significant contributor to the national construction value. However, the CI’s growth is occurring at the expense of social, environmental and economic impact on the New Zealanders. The impact has urged the need for Sustainable Construction (SC) for the NZ CI. SC is a well-known concept, which is used as a method to optimise resource consumption, minimise waste and maximise investment returns. Three key aspects of SC are social, economic and environmental. All SC aspects are independent yet interlinked. Some of the important environmental elements are resource consumption, land and water pollution, energy consumption and C&D waste. The literature finding that brought attention was C&D waste labelled as the third largest waste stream in the world, largest waste streams in Auckland and NZ. However, less interest has been shown in minimising C&D waste, especially through life cycle thinking i.e. pre-design, design, construction, refurbishment and demolition. In addition, knowledge gaps exist in the implementation of C&D waste minimisation approaches to advocate SC. The overarching aim to develop a C&D waste minimisation framework considering life cycle thinking is achieved through a mixed-method approach. This study conducted semi-structured exploratory interviews and on-site observations to achieve the research aim. A pragmatic approach was adopted for the data collection. Further, data analysis was done through multiple techniques, for example. thematic analysis, content analysis and descriptive analysis. The finding of this study provided factors influencing C&D waste, challenges in C&D waste minimisation and their remedial measures. In the pre-design stage, contractual requirements were identified as the most influencing factors and the top challenge. One of the remedies, is putting a waste minimisation clause (mandatory/voluntary) in the contractor document. Subsequently, in the design stage, the circular economy was identified as the most influencing factor and a leading challenge for CI practitioners, which needs to be addressed through client education and demand. Further, in the construction stage, waste sorting was the most influencing factor and the top challenge. Contractors need to use multiple bins on-site depending on the activities and educate site labourers through tool-box meetings to sort waste efficiently. In the refurbishment stage, environmental impact of refurbishment waste was the most influencing factor and key challenge. The remedy for this challenge was found to be the introduction of compliance for reuse. In the demolition stage 10R thinking (Refuse, Rethink, Reduce, Reuse, Repair, Relocate, Remanufacture, Repurpose, Recycle and Recover) and waste levy, were the most influential factors and top two challenges. Increase in waste levy for landfill and introduction of waste levy for C&D waste fills, was noted as a positive step towards waste minimisation. 10R thinking needs to be stimulated in the Auckland CI through: providing technical and financial guidance to innovative businesses; investing in remanufacturing and recycling infrastructure; and commercialisation of innovative waste minimisation ideas. This study proposes a waste minimisation framework and required actions from clients, contractors and policymakers and influencers to promote C&D waste minimisation. Some of the most significant actions are: • Client: Demand for eco-labelled materials and changed attitude towards second life products. • Contractors: Establish SC group and implement product stewardship scheme • Policymakers and Influencers: Support innovative businesses For efficient waste minimisation, actions from one group requires support from other two groups. For instance, if policymakers decide to fund community recycling centres, the client needs to demand sustainable materials, and contractors need to use them. The proposed waste minimisation framework attempts to promote C&D waste minimisation and serves as a guideline for practitioners and researchers to establish a link in current research areas and future trends.