Starting from a practical design problem related to natural and hybrid ventilation systems, this paper looks at different airflow modeling methods that might be employed to assist in the decision-making process of a building design team. The question at hand is whether or not to make use of a double-skin façade system in a new office development. The airflow modeling methods considered are the mass balance network method and computational fluid dynamics (CFD). The paper gives an overview of the methodology of the design study. The underlying modeling and simulation work is elaborated. The paper finishes with some conclusions, both in terms of the actual performance of the double-skin facade and in terms of the modeling and simulation work. The main conclusions are that, for the foreseeable future, the network method is more suited for this type of "everyday" design support work. However, there are important areas where the network method in general might benefit from CFD, or vice-versa.