Stocks, flows, services and practices: Nexus approaches to sustainable social metabolism

Societies use material and energy resources to build up, maintain and utilize long-lasting structures such as buildings, infrastructures or machinery, i.e. entertain a ‘social metabolism’. Nexus approaches provide useful heuristics for interdisciplinary analyses of (un)sustainable society-nature interactions, for example by highlighting relations between different resources (e.g. land, water and energy). Assuming that social metabolism is mainly motivated by the aim of deriving benefits from products or services leads to the concept of a ‘stock-flow-service nexus’. This nexus approach connects biophysical stocks and flows involved in social metabolism to the services, benefits and well-being contributions they provide to society. It thus reaches beyond narrower concepts of ‘eco-efficiency’. At the same time, it remains mired in controversy over the valuation of services. The complementary approach of a ‘stock-flow-practice nexus’ is focused on the relationships between stocks, flows and practices, i.e. the routines of everyday life linked with resource use. Building on prominent theories of practice, in particular those that have gained traction in consumption research, it avoids controversies around the service concept and offers a fresh perspective on structure-agency issues at the heart of social metabolism. In this conceptual article, we discuss how these two complementary nexus approaches can serve as heuristic models for interdisciplinary sustainability research and sketch the different conceptual and empirical research directions each of these two approaches inspires.