The effect of space depth on improving natural ventilation with a focus on solar chimney performance

About a third of the total energy consumption in developed countries is summarized in the housing and building sector, while the provision of cooling, heating, and air ventilation. In this regard, air ventilation is a significant issue and a large part of the energy consumption in the building is dedicated to this issue. Various methods for natural ventilation have been exempted from sustainable architecture, one of which is solar chimneys. A solar chimney is a type of passive solar heating and cooling system that can be used to regulate the temperature of a building as well as provide ventilation. Like a Trombe wall or solar wall, solar chimneys are a way to achieve energy-efficient building design. Essentially, solar chimneys are hollow containers that connect the inside part of the building to the outside part of the building. Various research have been conducted in connection with the analysis of solar chimney performance; meanwhile, there has been no independent research regarding the effective depth of the solar chimney in creating ventilation in a closed space.

Accordingly, in this research, the issue of the effective depth of the space in improving the ventilation performance of a room equipped with a solar chimney is investigated. The research method used in this article includes two qualitative and quantitative parts. In this research, assuming that the depth of the space affects the amount of ventilation, the depth is considered as an independent variable, and the amount of airflow is a dependent variable. For this purpose, 7 rooms with fixed width and variable lengths were selected as case studies. The length of the rooms fluctuated from 3 meters to 9 meters, and the width of the room was considered a fixed value of 3 meters in all cases. A solar chimney with a height of 1.85 m, a width of 1 m, an air gap of 0.28 m, and an angle of 75 degrees is placed on the roof of the chamber in all the case studies. After the samples were selected, they were simulated in the Autodesk CFD soft wear. To measure the accuracy of the calculations, the validation of the software was done, and the result of this part was a 4% error between the numerical results and experimental research.

The results of this research showed that the ventilation speed has a direct relationship with the depth of the room. The most optimal dimensions of the room in terms of room ventilation are 4x3 and 5x3. Also, in the standing height, the minimum ventilation speed is seen in the end part of the spaces, and in the sitting height, except for the beginning and end of the room, the lowest speed is at one-third of the end of the room.