Airflow Rates between Multiple Rooms by Using Multiple Gas Technique

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Air distribution in airtight houses should be carefully designed in order to prevent future problems with air quality. It is important to understand airflow paths and interzonal airflow rates in such houses. One method for calculating ventilation rates within a house is the multiple tracer gas technique, the accuracy by using it do not have always evaluated by the other method in a strict sense. Usually, most houses do not have a device for measuring airflow rates. Accordingly, the multiple tracer gas technique can be used for measuring the airflow rates in such houses.In this study, the interzonal airflow rates in actual-sized test houses or in model spaces were measured by using the multiple tracer gas technique. The results obtained from the multiple tracer gas technique were compared with those obtained from other method such as a differential pressure method in order to evaluate the accuracy of the tracer gas technique.The multiple tracer gas technique is evaluated by using actual-sized test houses or model spaces with known airflow rates. The experimental results can be summarized as follows:(1) The values obtained by tracer gas technique have errors of 20 %, to 30 %. This degree of accuracy is similar to those shown in the previous reports.(2) When the degree of air-tightness was low (e.g., 5 cmィイD12ィエD1/mィイD12ィエD1), the errors became larger. As a large number of cold drafts produce an extreme distribution of gas concentrations, a fan should be used to diffuse them if the airflow paths are not affected by the use of the fan.(3) If the kinds of tracer gas used are restricted, the modeling should suppose the interconnected space to function like an imaginary duct. If the volume of the interconnected space is not considered in the calculation of airflow rates between zones, the results of the calculation is almost unaffected. In addition, we found that we can calculate the interzonal airflow rates between restricted zones by using some restricted tracer gases.