Carbon Dioxide Concentration and its Application in Estimating the Air Change Rate in Typical Irish Houses

In this study, the function of carbon dioxide as an index of indoor air quality and as a tracer gas to estimate the air exchange rate in naturally ventilated single family houses was investigated. Carbon dioxide concentrations were measured continuously in the occupied room of six selected Irish houses for periods of 2 to 7 days. The air change rates were then calculated according to the mass balance equation and the time variation of carbon dioxide levels. In each house, SF6 tracer gas decay tests and fan pressurization tests were also conducted to estimate the ventilation rates and the average infiltration rates according to recommended test procedure. A comparison of the different methods was made to find out the relations of the results. The correlations between calculated ventilation rate and maximum room carbon dioxide levels were also discussed. Results show that occupant generated carbon dioxide can be used in dwellings to estimate the ventilation rates, and the time variation of carbon dioxide concentrations indicate some houses are at risk of poor indoor air quality caused by inadequate ventilation.