Energy efficient data aggregation is an essential system requirement for the type of wireless sensor network used in highly-reliable applications (e.g. surveillance, fire detection etc.). Recent research works shows that significant energy saving can be achieved in WSN's by using Mobile Element (ME), capable of effectively carrying the data's mechanically. The main reason for energy consumption is due the heavy involvement sensor nodes in data recovery, processing, buffering and distributing tasks. Thus we proposed to minimize the overall network overhead by building cluster structures and also balance the energy expenditure through exploiting ingress nodes, which is located in propinquity to the preset ME trajectory. Assigned Cluster heads collect the recorded information from the sensor nodes and perform filtering upon raw data and forward the filtered information to the appropriate "Ingress Node". The latency in data collection due to low speed of Mobile element can be addressed by using subset of nodes as ingress nodes that buffer and aggregate data from other nodes and transfer to the ME when it arrives, achieving a balance between energy saving and data collection delay. Surplus workload of CH's leads to decrease in network efficiency which is recovered by dynamically changing the role of cluster head by using HEF algorithm, considering the energy drain as a major factor. © 2013 IEEE.