23 FOCUS I Jordan University of Science and Technology Abstract The paper investigates the influence of different courtyard wall geometries on the thermal performance and natural ventilation of adjacent spaces in a typical two-storey building. Computer simulations using IESVE were conducted to assess the impact of various wall configurations, including vertical walls, inward staggered walls, inward sloped walls, outward staggered walls, and outward sloped walls. The wall geometries play a crucial role in regulating thermal performance and natural ventilation within the rooms surrounding the courtyard. The ratio of the courtyard's top width to its ground width (T/G) affects the flow patterns inside the courtyard. The findings suggest that courtyards with outwardly sloped or staggered walls exhibit improved heating load performance and promote increased air movement within the courtyard and facilitate better air exchange between the courtyard and the adjacent spaces. Courtyards with inwardly sloped or staggered walls demonstrate enhanced cooling load performance. Based on these results, a courtyard with an inwardly staggered or sloped wall is highly recommended for hot climates. In contrast, a courtyard with an outwardly staggered or sloped wall could be utilized in an overcast climate. Keywords: Courtyard wall geometries, Thermal performance, Natural ventilation, CFD Simulation, IES VE software. Introduction The main goal of energy-efficient building designs and the role of passive design devices is achieving the needs of users with minimum energy consumption and less impact on the environment and natural resources. It emphasizes the significance of courtyards as a traditional architectural feature that can regulate and control the interaction of indoor spaces with the outdoor environment. Courtyards can provide climatic protection, visual and acoustic comfort, and contribute to energy efficiency. The quality performance of a courtyard relies on two main strategies: shading and natural ventilation. Shading helps control solar radiation exposure to the courtyard's envelope, reducing heat gain in the summer and increasing heat gain in the winter. Natural ventilation replaces hot air with cooler air, effectively lowering the courtyard's temperature. Several studies have been conducted to explore the potential and challenges of courtyard design. Akbari et al. (2021) investigated various geometrical parameters of courtyards and their impact on performance throughout the year. They found that these parameters had contradictory effects during different seasons. Sánchez de la Flor et al. (2021) developed a methodology to assess the energy-saving potential of courtyards, concluding that they can significantly reduce cooling loads, particularly in lower floors. Lopez-Cabeza et al. (2022) focused on the role of building materials, specifically the albedo (reflectance), in inner courtyards of urban heat islands. Their simulation-based study revealed that high albedo surfaces resulted in improved comfort and significantly reduced surface temperatures compared to low albedo surfaces. Lizana et al. (2022) studied the mitigation of urban heat impacts on building performance in inner courtyards. Their findings demonstrated that courtyards can effectively reduce discomfort hours and mitigate the effects of urban overheating by over 88%. Freewan (2011, 2019) investigated the influence of courtyard wall geometries on daylight performance. Different configurations were recommended based on climate conditions. Horizontal elements or multi-layered configurations were suggested for hot climates to enhance daylight performance, while specific configurations were preferred for regions with overcast climates or low daylight availability to increase illuminance levels. Overall, these studies underscore the significance of courtyards in energy-efficient design, considering factors such as shading, natural ventilation, building materials, and daylight performance. This paper addresses the gap in previous research by examining how courtyard wall geometries can enhance the courtyard's performance as microclimate modifiers in hot climates. It also introduces new courtyard forms for improved thermal efficiency. The study focuses on Aqaba, Jordan, which experiences hot and dry summers and cold winters. The cooling period is from May 1st to September 30th, and the heating period is from December 1st to February 28th, simplifying the calculations. By considering the specific climate conditions of Jordan, the research aims to explore the impact of courtyard wall geometries on microclimate regulation in a hot climate context. The present paper aims to fill the gap in previous research by exploring the impact of courtyard wall geometries on the courtyard's performance as microclimate modifiers, specifically in hot climates. It also introduces new courtyard forms that can be efficient during summer or winter. Jordan, located at a latitude of 29.53°N and a longitude of 35.0°E. Aqaba, being the southernmost region in Jordan, was selected as the location for the study. The cooling period for the simulation was set between May 1st and September 30th, while the heating period was between December 1st and February 28th as seen in figure 1. These periods were chosen based on air temperature measurements in Aqaba, taking into account the heating and cooling load requirements. The selection of these periods simplifies the calculations while capturing the relevant seasonal variations in temperature. By focusing on the specific climate conditions of Jordan and the chosen location of Aqaba, the study aims to investigate the impact of courtyard wall geometries on the courtyard's performance as microclimate modifiers in a hot climate setting. Fig.1 - Max and Min Air temperature in Aqaba- Jordan Research parameters The study focuses on two key variables to investigate the courtyard as a microclimate modifier: courtyard wall geometries and the ratio of the courtyard's top opening width to its ground width (T/G). The main design principles involve minimizing heat gain in summer and maximizing heat gain in winter. The courtyard wall geometries were varied by implementing different types of walls (staggered and sloped) for the rooms on the north and south facades of the courtyard. The T/G ratio was introduced to THE IMPACT OF MODIFYING COURTYARD WALL GEOMETRIES ON THERMAL PERFORMANCE AND NATURAL VENTILATION OF TWO-STOREY BUILDING Ahmed A. Freewan I Anas Khatatbeh I