This is a summary of an extensive research project on natural ventilation and thermal comfort in courtyard buildings in the Historical Centre of Havana. Based on a morphological study, a field work and a comfort survey (reported in previous papers), Computational Fluid Dynamics (CFD) simulations, thermal simulations and a comfort analysis are performed in theoretical generic courtyard buildings inserted in the compact urban morphology of Old Havana. The results of this study can be useful in order to promote the design of comfortable low-energy residential buildings in Old Havana in particular and in other compact cities in tropical-humid regions in general