The present work is on the implementation of a multi-functional ventilated façade model within an existing parallel and object-oriented platform for the prediction of the thermal performance of the buildings. Owing to its modular design, and its versatility, different configurations of new or retrofitted buildings can be numerically analysed using the present methodology, which is intended as a powerful design and optimization tool. The potential of this tool is tested for the numerical study of three retrofitted public buildings located in different climate conditions in Europe, proving to be a useful tool in predicting the channel width that maximizes the evacuated heat, thus helping to achieve the selection of the best possible retrofitting solution, customized to the needs of each particular building.