Double skin façades are façade technologies that have the perspective of reducing energy use and improving comfort in buildings due to their adaptable nature. Exhaust-air façades offer the possibility to utilize solar energy by recovering heat from the façade cavity. However, the cavity overheating can be detrimental on the summer performance. Predicting performance and optimizing the system during the design phase is a challenge, especially when the cavity-air is integrated into the HVAC system. Whole-building energy simulation (BES) software tools are an adequate tool for calculating whole building performance, although these can have limitations in the accurate replication of complex building elements. The paper analyses the available and applied modelling approaches within a BES tool, and compares the outputs in terms of cavity temperature, horizontal and vertical temperature profiles, and heat flux through the façade. The sensitivity of the results on the modelling approach is evaluated. Results can serve as a guide for practitioners on the selection of the modelling approach for a given task.