The primary advantage of CO 2 is that the human body can be used as its release source. In comparison with SF6, carbon dioxide (CO 2) is cheap to manufacture, easy to measure, and less harmful to the environment than SF6. Therefore, the SF6 concentration decay method is not suitable for long-term or large-scale use in civil building and practical engineering. However, SF6 is a powerful greenhouse gas, and SF6 itself along with the measuring instruments is very expensive. Some studies have shown that the average calculation error of air exchange rate (AER) could be controlled within 8% using the SF6 concentration decay method when the rate of infiltration air change is artificially controlled and the indoor fan stirring is enabled. As a result, a small amount of SF6 can be used to quickly estimate the infiltration air change rate in a closed room. The AIVC and several other organizations found that the most perfect tracer gas is sulfur hexafluoride (SF6), which is chemically stable and is normally not found in the natural environment as it is man-made. The AIVC has been offering technical support for industry and research organizations who aim at optimizing ventilation technology. In 1979, the International Energy Agency (IEA) inaugurated an Air Infiltration and Ventilation Centre (AIVC) to recognize of the impact of ventilation on energy use and indoor air quality. It is very difficult to accurately and rapidly measure the infiltration rate in air changes per hour (ACH), although the development of the tracer gas technique provides ways for solving this problem for about 40 years. Our results indicate that the ASHRAE China-specific modified model has the best performance with an average deviation of −6.67% and a maximum deviation of −14.6% with multiple measurement points, a stable personnel activity, and proper Parameter settings in a single room in China.Īs one of the common ways of passive ventilation in civil buildings, infiltration has a non-negligible impact on the energy consumption, thermal comfort, and indoor air quality of buildings. We also analyzed the potential factors that could affect the uniformity of the indoor tracer gas distribution. We verified these models by comparing the exhaled CO 2-based AER with AER from field measurements using sulfur hexafluoride (SF6) as a tracer gas. This study introduced three models (the ASHRAE model, the ASHRAE China-specific modified model, and the BMR model), which were proposed to estimate the AER based on exhaled CO 2. The tracer gas method was widely applied to estimate the AER in these buildings, and human metabolic carbon dioxide (CO 2) was often used as a tracer gas in different models. It is difficult to accurately measure the air exchange rate (AER) in residential and office buildings during occupation via on-site field measurement.
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