MAIN TAKEAWAYS

• The main difference between the natural ecosystem and the built environment is that natural ecosystems are closed cycles, and mostly, a zero-waste metabolism. Contrary to this, the highly urbanised built environment operates in a linear metabolism.
• Sankey diagrams are used to describe the metabolism of a city by indicating the flow quantity through the width of an arrow. Additionally the ASMFA (Activity Based Spatial Material Flow Analyses) identify the economic activities from products and services by mapping the input (water, raw materials or energy), the outputs (wastewater, waste) and the stocks, which are materials or products that stay within the activity.
• The input of one activity might derive from the output of other activity, and in this way, economic activities are connected through the whole value chain. This will eventually draw a systems diagram, which shows the sectors, related activities, and the material and energy flows.
• Territorial metabolism refers to a multidisciplinary and integrated concept that examines material and energy flows in territories as complex systems.