Abstract：

Carbon dioxide (CO₂) as a tracer gas is widely applied to estimation of air exchanges in buildings. Air changes are often used as an important characteristic of the indoor environment, and have a significant impact on human health. However, measuring air changes in an easy, effective, real-time and low-cost way in natural ventilation residential buildings is still a huge challenge. Presents a new method to release a stable rate of the tracer gas CO₂, by using dry ice contained in an insulation barrel. In theory, the sublimating rate of the dry ice should remain constant, as long as there is sufficient quantity of dry ice in the barrel. In other words, the sublimating rate of dry ice should be the same at any time once a steady state heat transfer has been formed. This method can be used with people present if necessary, and can be used in almost all types of applications both natural and mechanical ventilation.