How to quantify natural ventilation rate of single-sided ventilation with trickle ventilator?

This study quantifies the natural ventilation rate in single-sided natural ventilation with a trickle ventilator, inserted in a window frame or a shutter box. The seasonal characteristics of natural ventilation in actual residential conditions were examined by long-term field measurements in a multi-residential building during spring and summer seasons. The wind velocities and pressure differences between indoors and outdoors in the summer season, which are the driving forces of natural ventilation, were relatively lower compared to the spring season. The turbulence intensity was greater in summer when the outdoor wind velocity was lower. During this study about 90% of the outdoor wind velocity was less than 2.5 m/s, and the wind speed and wind direction constantly fluctuated. The ventilation rate of the trickle ventilator was quantified by four methods: the tracer gas method, inlet air velocity-based, pressure difference-based, and reference wind velocity-based. The tracer gas method was considered the reference to which the other three methods were compared. The calculation method based on the indoor/outdoor pressure difference, which is widely used for calculating the natural ventilation rate, failed in this case to capture the actual natural ventilation rate; only 63% of the ventilation rate quantified by the tracer gas method could be explained by this method. In addition, the reference wind velocity-based quantification showed the worst agreement, with an error rate around 54%. The inlet air velocity-based quantification of the ventilation rate showed the best agreement with the results of the tracer gas method in the trickle ventilator.