To mitigate the overheating problem in the warmer seasons, and thereby improve thermal performance and energy efficiency of the double-skin facade (DSF) system, this study introduced an innovative design approach involving the integration of passive thermal mass technique with the air channel of the conventional DSF. To assess the contribution of this integration to energy efficiency of the system, a numerical model was developed, capable of determining the thermal performance of the conventional DSF. The numerical model is composed of airflow and thermal models. This paper briefly describes the development of the models as well as the models' verifications. Models were then used to carry out a series of parametric studies to investigate the effect of thermal mass on the energy performance of the integrated system. The simulation results revealed that mechanically ventilated DSF can save energy based on configuration from 21% to 26% in summer and from 41% to 59% in winter as compared to conventional DSFs without thermal mass. The results also showed the total saving for a naturally ventilated DSF is negligible year-round. (C) 2010 Elsevier B.V. All rights reserved.