Two approaches have been established to develop urban metabolism studies. An ecological approach to urban metabolism was developed by Howard Odum, which is a conceptualization of energy flows that he termed Emergy, measured in solar emergy joules. An engineering approach to urban metabolism, developed by Baccini and Brunner, involves the quantification of energy and material flows in standard mass units, using Material Flow Analysis. In this video both methods are presented to describe the methods and demonstrate their application, as they apply to cities and urban sectors.