Existing green/eco responsible approaches for IT are frequently domain-specific and very focused on one topic. For example, some works are focused on saving energy with better virtual machine management on cloud infrastructures or data management in wireless sensor networks, in order to minimize the data transfers and sensors’ wakeups. Nevertheless, they consider only limited aspects in the whole software development process; indeed, very few researches propose a global approach. In this context, we envision a green development methodology that approaches energy saving aspects from the design phase and at all the system layers (software, hardware, user requirements, execution contexts, etc.), which can provide positive leverage as well as avoid side effects (one decision can be positive at one system layer but may trigger negative impact on other layers). We motivate the interest of this vision and describe key ideas regarding how to address these considerations in the development methodology.