About the use of CO2 as tracer gas for identification of air renewal; combination with co-heating test

Three types of tracer gas test are, until now, mentioned in international standards: Injection at constant indoor concentration, injection at constant flow rate and transient injection followed by a recording of the decontamination curve. A fourth method is proposed in this paper: it is based on the same scenario as the third method, but with weighting of the mass of tracer gas (CO2) injected and integration of the curve of indoor concentration on the whole testing period. The concentration peak is used to identify the “effective” volume of the building zone considered; this volume, associated to the final concentration, is used to calculate the amount of CO2 remaining inside the zone at the end of the test. The total mass of renovation air is then deduced from the corresponding CO2 mass balance. The CO2 can be injected from a bottle or directly produced by combustion on site. In the latter case, the tracer gas method is combined with a co-heating test. It can be done, for example, with a current camping butane cooker: From the weighting of this device and continuous recording of air temperature, CO2 concentration and humidity ratio, three significant (energy, CO2 and water) balances are established in such a way to verify and tune a reference simulation model of the building zone.