Systems on Chip (SoCs) congregate multiple modules and advanced interconnection schemes, such as networks on chip (NoCs). One relevant problem in SoC design is module mapping onto a NoC targeting low energy. To date, few works are available on design and evaluation of mapping algorithms. The main goal of this work is to propose some algorithms and evaluate its results and performance with regard to low energy NoC mappings. These include exhaustive and stochastic search methods and heuristic approaches, and some combinations. The use of combined approaches compared to pure stochastic algorithms provides average reductions above 98% in execution time, while keeping energy saving within at most 5% of the best results. In addition, one heuristic provided average reductions in execution time above 90% when compared to pure stochastic algorithms, and obtained better energy saving than combined approaches.