To reduce energy consumption in a duty-cycled asynchronous wireless communication network values of operation parameters, i.e. duration of the awake interval and duration of the sleep interval, of routing nodes of the network are determined and set. The network is partitioned into clusters so that each cluster comprises one cluster-head node. The energy consumption of a cluster is a function of the probability of busy channel when nodes of the cluster attempt transmission, the probability of communication collision during transmission, the duration of the awake interval and the duration of the sleep interval of its cluster-head node. Reduction of the energy consumption is carried out under predetermined values of the probability of busy channel and of the probability of communication collision and under predetermined constraint for the probability of successful transfer of data packets within the cluster and for the average delay of transfer of data packets within the cluster.