We formulate two kinds of sustainability criteria by using feedback and arbi- trary rules for selecting policy variables in non optimizing economies. We show that when policy variables are selected arbitrarily their accounting prices could determine sustainability in addition to the accounting prices of the economy?s assets. We use our theoretical framework to obtain es- timates of sustainability conditions in real economies. Thus, the paper?s contribution consists in developing a systematic theoretical framework for determining value functions, accounting prices and sustainability criteria, under fairly general non-optimizing behavioral rules, and then showing that this framework can be used in applied work to estimate sustainability con- ditions. Based on our theoretical model, we examined the case of the Greek economy. When there is no binding environmental policy then migration rate, growth of capital per worker and exogenous technical change are strong positive factors for sustainability. When we introduce potential environmen- tal damages due to sulphur dioxide (SO2) emissions, our ?ndings indicate that these damages a?ect negatively the sustainability criterion.