The article proposes an explicit modelization of households behavior by describing the possible relationship between the inter-temporal substitution rate and the opportunity cost of time which could afford the missing link between consumers' choices and macro variables in an Austrian trade cycle tradition. The changes of the value of time during expansions and recessions involve direct and indirect changes of households' demand and saving which create shadow prices. The variations of shadow costs are related to the competitivity of markets restoring equilibria by means of associated changes in monetary prices.