Energy consumption of computers rises with the continuous development of more powerful and complex components. To counter the increase in energy consumption resulting from this continuous developments, several solutions were implemented over the years including manufacturing more efficient hardware by shrinking the size of various components like the transistor or optimizing the software used to consume less energy. Many people nowadays use separate computers for work and entertainment with each one being used mainly to perform one or a couple of specific tasks like writing documents, compiling code or video editing. This thesis investigates if the operating system (OS) influences the energy consumption of software and algorithms running on it. To archive this, a series of tests were conducted. These include algorithms written in different programming languages and different software. In addition, the tests were performed across three different operating systems on two different computers. This not only allows the impact of different operating systems on the efficiency of programs or algorithms to be examined, but also whether this impact is the same with different hardware. The result of the conducted tests showed that some algorithms exhibited an increase in efficiency and performance of up to 50 % by simply changing the operating system.