Engineering models generally find that most consumers are unwilling to adopt energy efficient appliances, even though the financial returns are positive. It is commonly thought that this is either due to market imperfections such as an incomplete credit market, very high intertemporal consumer...

Gorman’s theory of demand is extended comprehensively to incomplete systems. The incomplete systems approach dramatically increases this class of models. The separate roles of symmetry and adding up are identified in the rank and the functional form of this class of models. We show that...