In monitoring scenarios, Wireless Sensor Networks commonly transmit measurements from a large number of sensor nodes to a central data sink. This communication pattern is known as concast. Different approaches have been proposed to improve the energy-efficiency of concast and thus the lifetime of the WSN. However, energy-efficiency evaluations that are close to reality are missing. This paper systematically analyzes the influence of aggregation strategies, tree topologies, and different MAC protocols on the energy-efficiency of concast communication. We implement a sample concast application and analyze it using the \avrorap simulator to gain realistic evaluation results. Our results disproof some common assumptions. We show that aggregation improves energy-efficiency only in a few cases and can even degrade it. Instead, MAC protocol and parametrization have a higher impact on energy-efficiency.