A first study of natural and hybrid ventilation systems in the urban environment

An experimental campaign was organized during the summer period 2002 in Athens, in the framework of the European RESHYVENT Project. The main purpose was to indicate the impact of the urban environment on the natural and hybrid ventilation air flow process in urban canyons. Field and indoor experimental procedures were carried out in two urban canyons, presenting different geometric and urban features. The experiments were organized for more than three consecutive days within three different periods in summer and on a 24-hour basis. Meteorological data around the buildings, inside and outside the street canyons were measured. A number of 114 ventilation experiments were conducted in three urban dwellings, consisting of natural, hybrid and mechanical ventilation, together with indoor environmental measurements. A first analysis of the observed airflow characteristics and the mechanisms driving the airflow inside canyons, as well as, of the estimated air changes for the applied ventilation systems is presented for one of the two studied canyons. The results of the second canyon are in process and will be compared with the present canyon in a future research in order to have general conclusions for the performance of these systems in canyons with different geometric characteristics under various outdoor urban conditions.