Material and energy flow analysis(MEFA)focuses on the role of resources for social and economic developmentand aims to inform sustainable resource management. One of itsfoundersis Robert U. Ayres59,76, who advocated the mass-balanced analysis of economic systemsas a counterpart to monetary-economic perspectives (Fig2).

Biophysical economicsfocuses on the central role of energy for the economy, which is often ignored in mainstream economics. Its founders include KennethBoulding58and Robert U.