The approach described in this paper aims to offer designers a new way to investigate use processes of products by integrating scenarios of expected user behaviour with simulations of physical artefact behaviour. Use is considered a key process in the life cycle of a product, being the phase in which an instance of a product is put into service or applied for its purpose. Our approach aims at resolving three issues: (i) dealing with the diversity of use processes in behavioural simulations, (ii) the integration of simulation and modelling approaches and (iii) extending the deployability of behavioural simulations towards conceptual design. Currently, options for behavioural simulation of the use process of a product are limited. Performing complete-picture behavioural simulation in which the product and the human user react on each other’s behaviours is not practicable. To make this possible, a hybrid approach is proposed. Behaviour that is commonly modelled based on the laws of physics is simulated as continuous behaviour, while information-processing behaviour is simulated as discrete behaviour. This paper elaborates on modelling and simulation of discrete behaviour and linking it to continuous-behaviour simulation. Scenario structures are introduced to represent knowledge about different human decision-making patterns that influence the courses of a use process. Depending on what is available to the designer, these can be based on observations from real users or on conjecture. The objective is to make what-if studies possible to compare different scenarios of product use. This is demonstrated with a pilot study of a basic use process.