Using multi objective optimization in term of position and area of the air outlet shaft in Showadan

Using the geothermal energy is one of the best solutions that led to construction of underground spaces in different parts of the world. "Shovadan" is one of the underground buildings which can be seen in the southwestern regions of Iran, especially in the cities of Dezful and Shushtar. Shovadan consists of a main space called "Sahn" that is usually built at a depth of 8 to 12 m under the ground and is accessed by a stairs. Fresh air enter the Sahn through these stairs and exit through a vertical channel called the air outlet shaft (AOSh). The configuration of various components of the Shovadan have a great impact on the thermal performance and ventilation efficiency inside it separately. In this paper a multi-objective optimization method is used to find the best position and the most optimal cross-section area of the AOSh. First, one of the most common forms of the Shovadan in Dezful city was selected as the base sample; then based on the different positions and cross sectional areas of the AOSh, 45 case studies were extracted for analysis. In the next step, the case studies were simulated in CFD and the average temperature and velocity inside their Sahns were calculated. Finally, using EDT analysis and Genetic algorithm (GA), the most optimal position and cross-section area of the AOSh were determined. The results showed that the most optimal case for thermal comfort in summer is formed when the distance between the stairs and the AOSh is increased and the cross-sectional area of the AOSh is decreased.