Nano-satellites emerged as pedagogical concepts thus having elementary functions. Today we face an increased deployment of cubesats for scientific and other space operations as well. This paper examines from a systems design perspective the adoption of one of the ECSS specifications at the cubesat level. Drawing from our experience on the development of UPSat, we conceptualize design challenges implied by satellite miniaturization. More specifically, based on the design approach we followed, we propose a design methodology for the implementation of the ECSS-E70-41A standard at the nano-scale. Depending on the mission requirements and the specificities of a cubesat platform, designers should adhere to, ignore or transform aspects of the standard.