Measuring technology and assessment of natural ventilation applied in a complex building

By natural ventilation, the air rate varies randomly. Therefore, it is difficult to evaluate the natural ventilation performance due to insufficient measured data. In the present work a complex office building was taken as a study object for the experimental investigation. A measurement technology is developed in this work for the assessment of the natural ventilation performance in the building. The measuring sensors for temperature, moisture and airflow velocity were located along the flow-paths of the natural ventilation and on some other dominant positions according to the structure of the building. An assessment system is proposed for the evaluation of the utility of the natural ventilation. The air rate of natural ventilation should be evaluated according to the necessary ventilation rate. In the paper, the necessary ventilation rate is determined by three factors: human health, indoor air quality and heat extraction. The alignment chart for the necessary ventilation rate can then be obtained. The complex building discussed in the paper was tested comprehensively in May, 2005 and was evaluated by the assessment system of nature ventilation proposed. The evaluation results show that the measured natural ventilation rates were always larger than the necessary ventilation rates, and the coefficient of ventilation effective utilization and the efficiency of ventilation exchange were always greater than 1. The air circulation ratio was 5 times per hour when the opening ratio of the lower windows was 28%.