Characteristics of airflow from open windows

In natural ventilation systems fresh air is often provided through opening of windows. However, the knowledge of the performance of windows is rather limited, especially with regard to their impact on thermal comfort and draught risk in the occupied zone. This paper describes and summarizes the results of a series of laboratory measurements that is performed on two different window types to determine the characteristics of the air flow in rooms. It is shown that the air flow can be described by traditional theory for jets and stratified flow and semi-empirical flow element models are developed for estimation of thermal comfort parameters in the occupied zone.