In this work, an energy efficient routing technique for WSNs is introduced. Here the routes between the source nodes and the base station are formed considering the energy levels of the intermediate nodes. These routes are refreshed dynamically to recover topology changes and to keep the energy level of the nodes close to each other. The technique introduced together with data aggregation are implemented on the WSN testbed at the department of computer enngineering, ITU. The results obtained have shown that the routing technique introduced and data aggregation contribute to the lifetime of WSNs.