Designs of architectural environments have 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 an 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.