Firstly, for the proper understanding of this project, the main architectures and technologies used to develop a network over fiber are going to be presented. In addition, some energy-saving models proposed by different working groups, applicable in a close future at the optical unit, will be introduced. Next, the most important devices used in the deployment of a network over fiber optics are shown. Also, the main technical data, relevant for some simulations described in the final part of the project, are presented. Finally, the results on the energy efficiency of the different technologies discussed will be shown. The efficiency of each one will be studied based on the most important physical parameters in the deployment of an access network over fiber.