The energy consumption in distributed systems depends on several inter-related factors, including task partitioning, process redundancy, fault tolerance, task and message scheduling, and communication bandwidth allocation. Although some of these issues have been considered in the literature in isolation, a systematic approach considering all the constraints is still missing. This paper addresses the problem of allocating a task set and the required communication bandwidth on a distributed embedded system, aiming at reducing energy consumption while guaranteeing timing and redundancy constraints. Two heuristic approaches are proposed and compared against a complete method and simulated annealing. Simulation results show the effectiveness of the proposed approaches.