Reflections on the FBS model: proposal for an extension to needs and requirements modeling

The paper proposes an extension of the Gero’s Function-Behaviour-Structure (FBS) framework aimed at representing Need and Requirements and their relationships with the Function, the Behaviour and the Structure of an artefact. Needs and Requirements can be modelled as further types of variables to describe with the same formal approach of the situated FBS model the transformation processes which occur in the earlier stages of design, when the requirements still need to be specifi ed. The proposed model is clarifi ed through a simple, but comprehensive example related to the design of a kettle.