Development of an automatic opening system for sliding and casement windows to control the natural ventilation rate

Abstract

Under the influence of COVID-19, ventilation is recommended to reduce the risk of infection in the room. Window openings can increase the ventilation rate caused by indoor and outdoor temperature differences. However, there is a concern that opening the window in the air-conditioned room will increase the heating and cooling loads due to air leakage. In addition, it is difficult to maintain an adequate ventilation rate because the outdoor temperature changes from time to time. To solve this problem, we have developed an automatic opening system to control the natural ventilation rate. This system can control the adequate ventilation rate for the room by adjusting the opening area of the window automatically. In this study, the control equations for the system for sliding windows were derived, and actual measurements were taken with the system. Additionally, the flow coefficients of the casement windows were numerically analyzed. Then, the control equation for the system for casement windows was derived from the relationship between the opening angle and the flow coefficient. As a result, the ventilation rate could be controlled using an automatic opening system for the sliding windows. Also, the flow coefficient of the casement window could be approximated by a sinusoidal function of the opening angle.