Windows Size and the Performance of Natural Ventilation

Abstract

Natural ventilation is efficient for passive cooling of buildings, to improve indoor air quality, occupant comfort and, consequently, the reduction of the use of electric energy. Characteristics such as the type of windows, if fixed or mobile; effective ventilation area; operation; if present elements that offer greater resistance to the passage of the air, it influences directly on the conditions of natural ventilation. Therefore, the present work aimed to compare the natural ventilation conditions that different window areas provide to an environment, by means of computational simulations using Computational Fluid Dynamics (CFD) - – Ansys CFX. To develop the study were changed dimensions of the inlet openings of a model, specifically the windows, to evaluate the influence of this parameter in the amount of airflow in the change rates, the pressure coefficients in the openings (windows and doors) and in the qualitative distribution of internal airflow. Two different dimensions were analysed: window area corresponding to 10% and 25% of the floor area, whose dimensions were determined based on codes and construction legislation. The conditions of natural ventilation were influenced by the modifications in the size of the openings and variation of the angle of incidence of the winds, presenting significant changes in the values of the pressure average coefficients and the air change rates. In addition, variations in the pattern of air flow distribution were also recorded.