AbstractNumerical simulations and computational fluid dynamics can be usefully integrated with architectural modelling to provide designers with a powerful single CFD based architectural modelling and design framework. This framework can be interfaced with building thermal performance modelling thus further integrating the full thermal and flow domains within architectural modelling. CFD analysis is generally restricted to the building’s environment flows or indoor single rooms and flow in spaces. In addition the designer must supply boundary conditions in the form of the external and internal building envelope/wall surface conditions. In the case of natural and mixed ventilation, this presents a fundamental problem since the outdoor and indoor boundary conditions are dynamic, inter-related and interactive via the building’s architecture. Furthermore they are dependent on external weather conditions, the indoor environment, controls and related heat gains. Therefore, in this study the boundary conditions ...