Search Results (2)

Natural ventilation is a common passive cooling method for improving air quality and thermal comfort; however, hot temperatures in summer and safety and privacy issues at night often result in its unideal performance. Therefore, we proposed the use of floor-level windows, mainly combined with microclimate improvement, to improve the indoor thermal environment by enhancing the cooling effect of natural ventilation during summer. Our study area was a house in Machida, Tokyo. We evaluated the effectiveness of our method in improving the indoor thermal environment in summer and performed a numerical simulation, while illustrating the detailed horizontal and vertical distribution of airflow in the house through the floor-level windows. The influence of different window types and opening angles of floor-level windows on ventilation and cooling was determined using the simulation. We found that: (a) natural ventilation-based passive cooling methods reduced semi-outdoor and indoor temperature and increased the humidity; (b) the airflow formed an indoor wind path; south-westerly inflow was from western floor-level windows and the skylight, and the outflow was from northern floor-level windows; and (c) the side hung windows (with an opening angle of 60°) were an ideal option to improve indoor airflow. However, there was no improvement in the passive cooling performance, due to the inflow of warmer outside air. Full article

As most existing office buildings in China lack fresh air systems for ventilation, natural ventilation with windows remains the main means of improving indoor air quality and adjusting indoor thermal comfort. However, knowledge of the ventilation characteristics of various window-opening forms in actual buildings is limited and current methods for evaluating ventilation performance lack a comprehensive consideration of ventilation rate and thermal comfort. In this study, the ventilation characteristics of different window-opening forms were systematically compared by conducting computational fluid dynamics (CFD) simulations. A full-scale experiment was conducted in a typical office room in a university in Tianjin to validate the CFD simulation. Two ventilation modes (wind-driven cross-ventilation and temperature-driven single-sided ventilation), three window-opening angles, and seven window types were investigated. Additionally, the ratio of the ventilation rate to the absolute value of thermal sensation was used to quantify the indoor natural-ventilation performance. The results showed that a sliding window with a full opening has the highest discharge coefficients of 0.68 and 0.52 under wind-driven cross-ventilation and temperature-driven single-sided ventilation, respectively, and top-hung windows opening both inwards and outwards have better ventilation performance than other window types under the two ventilation modes. This study is applicable to the design and practice of natural ventilation. Full article