Abstract: This paper presents a study of the runtime, memory usage and energy consumption of twenty seven well-known soft- ware languages. We monitor the performance of such lan- guages using ten different programming problems, expressed in each of the languages. Our results show interesting find- ings, such as, slower/faster languages consuming less/more energy, and how memory usage influences energy consump- tion. We show how to use our results to provide software engineers support to decide which language to use when energy efficiency is a concern.