EXPERIMENTAL STUDY ON AIR EXCHANGE EFFICIENCY IN HOUSES WITH CENTRAL VENTILATION SYSTEMS

This paper describes the results we got from the field measurement of air exchange effectiveness (i.e. local mean age of air and local air exchange index). The measurement was carried out on two wooden houses equipped with different kinds of ventilation systems. The results are as follows: (1) The value of local mean age of air, based on the definition of AIVC [1] and measured by the step-up tracer-gas method, is twice to five times as large as the value got through the step-down tracer-gas method, because of the infiltration of the houses. (2) The value of local mean age of air, based on the definition of Sandberg [2], is nearly the same through both the step-up and step-down methods. (3) The spatial distribution of local mean age of air (TP) and local air exchange efficiency (EP) is very large when a circulating fan is not operating, but when a fan is working the distribution of TP and EP is relatively small