Nowadays, Wireless mesh networks are being widely used as a cost-efficient means for coverage extension and backhaul relaying between IEEE 802.11 access points (APs). Recently, there has been a proliferation of application development that involves wireless access networks which is responsible for the raising in consumption and increasing demand for energy which results in the increase in carbon dioxide levels in the environment. This paper focuses mainly on different existing energy conservation methods in different networks. Several approaches are presented and discussions on the details related to energy management WMN are also presented. The classification of the layers of TCP / IP model of the largest existing approaches spent on energy conservation is treated.