The Impact of the Combination of Positive and Negative Spaces on the Performance of Solar Chimney; Case Study: Office Buildings in the Hot and Dry Climate of Shiraz

Given the intense rise of the world's population and ever-increasing energy consumption, the application of passive solutions is of paramount importance to the development of countries. A large share of energy consumption is attributed to the construction industry and office buildings, whose consumption levels can be significantly reduced through passive solutions such as solar chimneys. Solar chimneys, also known as thermal chimneys, greatly contribute to reduced energy consumption and thus can be employed for building ventilation, as well as heating and cooling by absorbing and storing solar energy. The present study aims to examine the effect of the solar chimney on ventilation and indoor temperature of office buildings in the hot and dry climate of Shiraz City, where buildings have different urban forms. In this study, a room with a solar chimney, in five different urban forms, is considered as a case study. The simulation is performed using ANSYS Fluent and Comsol Multiphysics software. By measuring the mean ambient temperature, inlet air velocity of the chimney and the amount of exhaust air pressure and comparing them in all four seasons of the year, it is found that the best performance in terms of ventilation is related to the summer season. Also, in cold seasons, the chimney should be closed so that the heat absorbed from solar radiation by the chimney keeps the environment warm. The values of temperature, velocity and pressure are only slightly varying in the models, but the findings indicate that the more the inlet air and the outlet air pressure, the higher the ventilation rate and the air change rate. With a slight difference, in the summer, the central courtyard is the most optimal urban form, which offers the highest increase in ventilation rate and decrease in energy consumption by being connected to a solar chimney, followed by the shaded courtyard on the north side and then the two-courtyard form.