Analysis of courtyard function in natural ventilation of traditional houses of coastal hot and dry climate using CFD technique (Case Study: Dehdashti Edifice in Bushehr City)

Subject Areas : Life Space Journal

malihe taghipour ¹ , Neda ghahraman izadi ² , Hamid Eskandari ³ , khosro movahed ⁴

1 - Associate Professor of Architecture, Department of Architecture, Faculty of Art and Architecture, Shiraz Branch, Islamic Azad University, Shiraz, Iran.
2 - Ph.D. Researcher, Department of Architecture, Faculty of Art and Architecture, Shiraz Branch, Islamic Azad University, Shiraz, Iran.
3 - Assistant Professor of Architecture, Department of Civil Engineering, faculty of Technical and Engineering, yasouj university, Yasouj, Iran.
4 - Associate Professor of Architecture, Department of Architecture and urban sustainability, University of the District of Columbia, Washington DC, USA.

Received: 2023-04-15 Accepted : 2023-09-30 Published : 2024-05-02

Keywords: Natural Ventilation, Courtyard&rsquo, s Form, Proportions, Mass, CFD Method,

Abstract :

The essence of the spatial organization of traditional houses in Iran's hot and humid climate should be found in the pattern of the central courtyard. An integrated and integrated structure that provides appropriate answers for the material and spiritual life of its residents over the years. Due to the lack of documented and systematic researches in examining and analyzing the characteristics, typology, classification, function and effect of the geometric shape of the central courtyard on the natural ventilation of the interior of hot and dry coastal climates, this research investigates the geometric structure and various types of the central courtyard in Bushehr traditional houses from the perspective of Climatic and factors affecting the behavior of natural ventilation. Therefore, the study of the form of the yard was done with the assumption that by changing the geometric shape of the yard, can control the velocity, local mean age of air inside the room. In order to determine the most optimal mode of benefiting from the wind for natural ventilation in the interior spaces, the most common characteristics of Bushehr traditional houses in terms of the form of the yard and room, the location of the openings and the classification of floors was classified in 9 different types. 9 different types of combination of geometric shapes of vertical rectangle, square and horizontal rectangle for the form of courtyard and room, 4 different modes of aligned and non-aligned openings and three height levels of ground floor, first floor and second floor, a total of 108 different simulation modes have been considered. In this article, by using a combined research method and using an experimental strategy, independent variables affecting the quality of natural ventilation were first identified, dependent variables were measured by precise digital devices in a case study (Dehdashti Building) and its data was used for software validation. In continuation and after typology of the yard, by cfd method and using Autodesk CFD 2018 software, 9 different types of combination of room and yard in the form of vertical rectangle, square and horizontal rectangle, in 3 height levels of ground floor, first and second floor was simulated. And it was analyzed based on the three components of "velocity", "local mean age of air". The shape of the yard, the shape of the room and the ratio of mass to space are considered as independent variables and the quality of air flow inside the room (velocity and life of air) is considered as a dependent variable. The findings show that with the increase in the length-to-width ratio of the rectangle from 1.15 to 1.3, in the case of a vertical rectangle, the velocity in the room first increases and then decreases, but in a horizontal rectangle, the velocity follows a more uniform trend. Since the more elongated shapes of 1/2 and 1/3 are less common for central courtyards and create tighter ventilation conditions, as a result, 1.1/3 proportions are desirable in real examples and this ratio has the amount of elongation which is necessary for good ventilation. In terms of Air flow speed: The contours show that vertical rectangular courtyards are the most optimal form of courtyards in terms of velocity, which has a relative advantage over square courtyards and has a better performance by a large difference compared to horizontal rectangular courtyards. According to Local mean age of air: The data shows that vertical rectangular courtyards with a small difference compared to the square and with a large difference compared to the horizontal rectangle have a shorter air life and fresher air quality. in general, considering the life of the air, the types of "vertical rectangular yard" have the most optimal air circulation in the yard and the types of "vertical rectangular yard" and "square yard" have the most optimal quality. Provides fresh air in the room. Meanwhile, type number 2 provides the most optimal quality of natural ventilation. From the direction of the pattern of wind movement in the yard, it can be said that in most species. The ground floor shows better air quality in the room, but with the increase in height, all three components increase. Key words: Natural ventilation, courtyard form, room form, opening, CFD method.