This paper presents the results of the thermal and airflow simulation of an existing naturally ventilated shopping mall located near, Lisbon, Portugal. Thermal and airflow simulation is used to improve the original natural ventilation system design in order to address winter thermal comfort problems that were due to excessive cold airflow in the mall corridors. In the first part of the simulation work, computational fluid dynamics (CFD) is used to predict indoor airflow velocities for different levels of building envelop airflow permeability. In the second part, a coupled thermal and airflow simulation model is used to investigate wether the more closed envelop generated a summer overheating problem. The simulation results for the optimized natural ventilation opening geometry show that it successfully addresses the mall winter discomfort problem while resulting in limited corridor temperature increase in the warm season. The third and final part of this study compares the energy consumption of a naturally ventilated mall with a conventional mechanically ventilated mall. (c) 2012 Elsevier B.V. All rights reserved.