Life cycle assessment of construction and demolition waste management systems: a Spanish case study

The aim of this study is to develop and analyse a life cycle inventory of construction and demolition waste (C&DW) management systems based on primary data collected directly from Spanish enterprises involved in the life cycle of this type of waste material. Special emphasis is placed on assessing the environmental profile of inert waste sorting and treatment (IWST) facilities. Taking the management of 1 t of C&DW as the functional unit, this study describes the boundaries of the C&DW management system and the scope of the research, which includes all stages from the temporary storage of waste in containers to its recovery or disposal on landfills. Primary data were collected directly from some Spanish enterprises involved in the life cycle of C&DW management: two firms that manufacture containers and bags, two companies responsible for the temporary storage of waste and transporting it, five firms devoted to sorting and treating the waste and two enterprises that operate inert landfills. Special attention was given to the IWST facilities, whose inventory data were related to four phases: pre-treatment and the primary, secondary and tertiary sectors. Finally, indicators were obtained for different impact categories. The environmental profiles of IWST facilities for mixed C&DW show that the greatest environmental impacts are produced in primary and tertiary sectors. From the life cycle analysis of C&DW management, it can be seen that transport, sorting and disposal make a net contribution to the environmental impact. Savings are due to the recycling of plastics, metals, aggregates and wood for all the impact assessment categories, except global warming in the case of wood and cardboard. Impact of IWST can be reduced by selective collection at source, since it avoids the separation of light fractions at plants. Life cycle assessment of C&DW shows that transportation stage plays a decisive role and recycling is not always beneficial.