A mobile ad hoc network (or manet) is a group of mobile, wireless nodes which co-operatively form a network independent of any fixed infrastructure or centralised administration. In particular, a manet has no base stations: a node communicates directly with nodes within wireless range and indirectly with all other nodes using a dynamically computed, multi-hop route via the other nodes of the manet. Simulation and experimental results are combined to show that energy and bandwidth are substantially different metrics and that resource utilisation in manet routing protocols is not fully addressed by bandwidth-centric analysis. This report presents a model for evaluating the energy consumption behaviour of a mobile ad hoc network. The model was used to examine the energy consumption of two well-known manet routing protocols. Energy-aware performance analysis is shown to provide new insights into costly protocol behaviours and suggests opportunities for improvement at the protocol and link layers.