IEEE 802.15.6 standard has been designed for wireless body sensor networks (WBSNs) that consist of several sensors and a coordinator node in, on or around the human body. In WBSNs, the body sensors continuously send their data to the coordinator node for remote healthcare applications. Continuously sensing body signals is a requirement for vital signs but continuously sending these signals to a destination over coordinator node is not necessary. Measured signs may be in a normal range for a healthy person, so these measurements may not be transmitted to a destination. In this study, the event-driven approach in an IEEE 802.15.6 based WBSN architecture are examined. If a vital sign exceeds the normal range in the proposed architecture, the corresponding sensor must send the sign to the coordinator node. In addition, a WBSN architecture is designed with the energy harvesting capabilities for purposing energy efficiency in a different way. Comparative performance analysis of three WBSN; traditional WBSN, event-driven WBSN, and energy harvesting aware WBSN is given in this study to show the impacts of energy efficiency methods to WBSNs. The event-driven scheme outperforms traditional WBSN, with a delay of 21% and energy consumption of 67% and the proposed energy harvesting aware scheme provides 5% additional energy to the traditional WBSN. Simulation results show that our proposed methods yield much better performance than the traditional approach.