During the past decades buildings have become one of the highest energy demanding component of cities, hence alternatives solutions been sought to reduce their impact. This study presents an experimen-tal evaluation to improve the thermal performance of roofs in semi-arid climate conditions when Phase Change Material (PCM) and natural ventilation are combined. In addition, the results evaluated the ther-mal comfort under an adaptive model. The performance of two modules (base and PCM) were defined as a function of indoor air temperature, lag time at peak temperature, surface temperature, and heat flux. Four configurations were evaluated: continuous roof components (Cases A) and with an air gap in the roof (Cases B), both with and without natural ventilation. The results, for the configurations with PCM, showed a maximum indoor air temperature reduction between 3.94% and 7.02% and a peak lag time between-10 and 70 min. Likewise, an increase in the solidification time of PCM between 19 and 41% was observed with natural ventilation. The configuration of PCM with 30 cm air gap without natural ven-tilation obtained the best result, reducing the maximum interior air temperature by up to 2.5 degrees C, 6.85% cooling load reduction, and thermal comfort improved by 50 min.(c) 2022 Elsevier B.V. All rights reserved.