Sustainability is one of the key engineering priorities of our time. The 3STARS project will introduce sustainability as an engineering discipline to software-intensive applications. It will establish a measurable quality model, accompanied with a dedicated rating scale. The capability to make accurate predictions based on sensing the world around us will drive the market for sustainable systems. Therefore, 3STARS focuses on simulation- and AI-driven methods. Effective system design and development processes, efficient tools, new computing and communication architectures, and increased system interoperability will lead to circular flows of digital artifacts, enabling new business models.