Situating needs and requirements in the FBS framework

The paper proposes an extension of Gero's Function–Behaviour–Structure (FBS) framework aimed at representing Needs and Requirements and their relationships with the Function, the Behaviour and the Structure of an artefact. Needs and Requirements are 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. The proposed model is clarified through an application to the information gathered within an industrial project to reduce water and energy consumption of a washing machine. By situating Needs and Requirements into the FBS framework, it is possible to properly represent all the tasks and the related cognitive processes characterising the earliest stages of the new product development.

► The FBS model is extended so as to comprise Needs and Requirements definition in the early stages of design.
► Needs and Requirements are ‘situated’ in relation to the External, the Interpreted and the Expected world.
► The revised model is illustrated by examples from a case study of innovative washing machine design.
► A parallel between the extended model, and one proposed by Simon in 1960 is drawn.