When assessing the sustainability of a product, an ideal life cycle is considered which could include the “Use” and “End of Life” phases. Does human behaviour affect the environmental sustainability? This paper intends to propose a methodological framework for assessing sustainable behavioural scenarios. The framework will be then developed in a specific case study on Compostable Single Use Products (CSUPs), with the aim of designing the identity of compostable materials for packaging in order to guide consumers to behave in a sustainable way in CSUPs disposal phase.