More than two months of detailed test data have been gathered using modified constant concentration tracer gas techniques for a six-storey, 60 apartment, multi-family building. Weather, and interior conditions in the building were part of the data set. Because of occupant effects, large changes in air exchange rates were observed, often over short time period. The test apartment allowed us to evaluate the influences of weather alone with the added feature to employ controlled window openings.
The use of passive perfluorocarbon technique for air flow measurements has been developed and tested. The building and testing of the system took approximately one year. The reproducibility of the analysis was tested during the period. The results show that the relative standard deviation of the analysis for parallel samples is less than 7 % for each tracer in most of the cases. A drift of calibration was noticed, but it can be allowed for by using reference samples with known amounts of tracers. The accuracy of the method was tested in controlled laboratory conditions.
The accuracy of tracer gas measurements of building air infiltration rates has been a widely discussed topic. One question that has often come up at past AIVC conferences is the ability of passive methods, such as the Perfluorocarbon Tracer (PFT) method, to accurately measure fluctuation air flow rates. A series of field studies is being conducted to compare the air infiltration measurements of the constant concentration tracer gas (CCTG) and PFT methods and provide recommendations for their proper implementation in the field.
In this paper we describe the development of a multi-tracer gas system for measuring interzonal air movement in buildings. The system consists of simple and stand-alone gas injectors and sampling units. The injectors are capable of releasing up to four perfluorocarbon tracer gases in different parts of a building. Following tracer gas injection and mixing, small samples of air are collected using automatic sampling units. Each unit consists of a 16-position valve and a group of removable stainless steel tubes packed with solid absorbent.
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