Efficiency in computer science often refers to the runtime or memory usage, that a certain algorithm needs to produce an output. However, efficiency can also describe the amount of energy, that is consumed by the hardware during the runtime of an algorithm. This course explains the relevant computer architecture components, as well as different coding techniques, that allow computer scientists to design and program energy efficient algorithms. Participants will learn how intrinsic functions work and how they can be applied to an algorithm to reduce its energy consumption. In addition, the course presents a hands-on approach to measuring energy consumption of programs using the Intel VTune Profiler tool. In contrast to the existing clean-IT courses on openHPI (https://open.hpi.de/channels/clean-it-forum), this course provides a deeper dive into specific, energy efficient, architecture coding techniques.