Combining Life Cycle Assessment and System Dynamics to improve impact assessment: A systematic review

Life cycle assessment has been widely applied to quantify the environmental impacts of products and processes; however recent studies highlight its limitations. Critics state that environmental impacts may be misrepresented if spatial and temporal dynamics of production systems are not accounted for. Some authors have used systems thinking methods to account for the temporal dynamics of production systems in life cycle assessment. These applications have been in the areas of solar electricity, wastewater management , electric vehicles, fly ash in cement, mobile phone waste, steel, and the long-term impacts of material sourcing amongst others. The approaches to combining systems thinking methods with life cycle assessment have been both qualitative and quantitative. Some studies have conceptualised the dynamics of systems using causal loop diagrams. They are a systems thinking tool used to map cause and effect as feedback loops that control system behaviours, nurturing a qualitative understanding of the system under study. Over sixty percent of the studies identified in this review have proceeded to using a rigorous mathematical evaluation of the system, namely, a system dynamics model in combination with life cycle assessment. This paper conducts a systematic review of efforts to combine systems thinking methods with life cycle assessment (in their various forms). In particular, it focuses on the two main approaches to combining system dynamics models and life cycle assessment: the inclusion of life cycle inventory and impact assessment factors in a system dynamics model and the inclusion of system dynamics model results in a life cycle assessment. The advantages and disadvantages of these two approaches will be discussed in this paper to provide guidance for future work. • Sixty percent of studies combined system dynamics and life cycle assessment. • There are two approaches to combining system dynamics and life cycle assessment. • Attaching LCA results to a system dynamics model was most frequently used. • Integration prevents overestimation of impacts when technologies change over time. • Integration prevents underestimation of impacts due to unintended consequences.