COSA is a project funded by the Scientific Commission V of the Italian Institute for Nuclear Physics (INFN). The main focus of the project is to investigate the performances, the total cost of ownership and the possibilities offered by computing systems based on commodity low power Systems on Chip (SoC). Computing performances will be measured running real life applications taken from the High Energy Physics (HEP) community belonging to the Institute. The project is building and maintaining three clusters. One is located in Bologna (CNAF department) and will be composed of development boards powered by the state of the art low power SoCs running Linux. Another one, located in Rome (ROME1 department) exploits the last generation FPGAs to prototype low latency network connections between low power CPUs. The third cluster, located in the Padova department, is based on traditional, non-low-power, CPUs, accelerators and network connections. This cluster is used as a reference for the performance of the scientific applications run on the other two clusters