Abstract. We demonstrate the manner in which high-level design requirements, e.g., as they correspond to the commonsensical conceptualisation of expert designers, may be formally specified within practical information systems, wherein heterogeneous perspectives and conceptual commitments are needed. Focussing on semantics, modularity and consistency, we argue that our formalisation serves as a synergistic interface that mediates between the two disconnected domains of human abstracted qualitative/conceptual knowledge and its quantitative/precisionoriented counterpart within systems for spatial design. Our demonstration utilises simple, yet real world examples. 1 Conceptual Modelling for Spatial Design This paper investigates the role of ontological formalisation as a basis for modelling high-level conceptual requirement constraints within spatial design. We demonstrate the manner in which high-level functional requirements, e.g., as they correspond to the commonsensical conceptualisat...