Abstract. The design of architectural environments has to take into account various sources of heterogeneous information. Not only quantitative spatial constraints and qualitative relations but also functionally-dependent and abstract conceptualizations are relevant aspects for architectural design. We aim at a modular ontological approach based on the theory of E-connections to formally present and bring together these different perspectives on the domain. Modularity here allows a flexible integration of the various sources while keeping their thematically different aspects apart. We show how modular ontologies reflect the domain for architectural design and how they can be applied to smart office environments in ambient intelligence. Keywords. Ontologies, Modularization, Heterogeneous Information, Architectural Design, Ambient Intelligence