The hot, arid climate of the Qassim region in Saudi Arabia poses significant challenges for energy-efficient building design, especially in terms of passive cooling strategies. Courtyards, a traditional architectural element, offer potential for improving thermal performance in such climates. However, the impact of courtyard plan aspect ratio and orientation on energy consumption in semi-detached houses remains understudied. This research addresses this gap by investigating the thermal behavior of U-shaped courtyards in arid climates through IES simulations. The study aims to assess the influence of different courtyard shapes (square and rectangular) and orientations (north, east, west, and south) on cooling loads in adjacent spaces. Two semi-detached house configurations, each featuring either a square or rectangular U-shaped courtyard, were modeled and analyzed. The findings indicate that square courtyards perform better than rectangular, reducing cooling loads during summer months. South-facing courtyards exhibited the highest energy consumption due to prolonged solar exposure, while west-facing courtyards had the lowest cooling loads. Furthermore, the results show that the internal zoning of rooms adjacent to the courtyard should be strategically planned based on thermal performance, as specific zones experienced varying cooling demands depending on courtyard shape and orientation. In conclusion, optimizing courtyard design, including plan aspect ratio and orientation, can significantly enhance energy efficiency and thermal comfort in arid climates. These insights provide architects with practical guidelines for designing more sustainable and energy-efficient courtyard houses. Future research could explore the integration of social and environmental aspects, as well as the impact of natural light on adjacent spaces