The rapid evolution of digital technologies and the resulting emergence of novel design methodologies are coinciding with climate change, population growth and increased pressure on global resources. This concurrence evokes opportunities to harness the new design methods to develop smart design solutions and processes that respond effectively to sustainability requirements. Meanwhile, parametric design is emerging as an ideal design methodology to support sustainably in design, whereby the associative parameters in parametric design systems enable automation and synchronicity in generating design forms and evaluating these forms against their environmental performance. This research explores the multifaceted way in which parametric design supports sustainability, and how this can lead to a more holistic understanding of sustainability by shifting the focus from sustainable buildings to sustainable processes. In addition, the work shows how the reusability of parametric definitions in parametric design applications can enable designers to recycle the design process, where a parametric definition acts as a building seed that can be 'planted' in different projects to automatically generate different forms. This may enable practitioners from all over the world to collectively develop a 'seed library' that has the potential for architects to empower, automate and enhance the environmental values of their processes. To achieve this, the main changes and shifts in computational design are reviewed, together with the impact of parametric design and its related applications on the architectural design process. In addition, a case study is conducted to explore how parametric design can significantly accelerate processes in real practice, and how the overlooked potential of reusing parametric definitions can make distinctive results in real architectural projects. Finally, the efficiency of the seed library is discussed as opposed to the apparent issues such as validity of seeds, motivation for sharing, and copyright.