Application of Adapted Tracer Gas Test for Ventilation Assessment in Two Locations

Abstract

In the wake of the current worldwide COVID crisis, the vital role of ventilation in keeping healthy indoor environments has become increasingly clear. But even before that, researchers have been pointing out how crucial ventilation is in avoiding the accumulation of pollutants in indoor spaces and in interpreting indoor air quality (IAQ) data. Given the importance of ventilation, especially in estimating pollutant sources’ strength and proposing remediation actions, it is imperative that IAQ assessments quantify the actual building ventilation rates. However, many IAQ field studies found in the literature do not report ventilation rates adequately. This paper describes the application of an alternative method to passively measure the average ventilation in two different locations. This alternative method consists of an adaptation of the traditional tracer gas test (TGT) used for long term average air change rates (ACH) measurement. This adapted TGT employs an alternative tracer gas (decane-D22) that is more adequate than the currently employed SF6 and perfluorocarbons. The selected tracer can be co-captured and co-analysed with commonly assessed VOCs by commercial passive IAQ-sampling. A passive source design of decane-D22, optimized in lab, provides stable and repeatable emission rates unaffected by varying RH and ACH. The actual source emission rate is determined from the average room temperature via an exponential prediction curve derived in lab. Results from the two field experiments described in this paper show the satisfactory applicability of the proposed adapted TGT in different types of environments and settings. The ultimate research goal is to provide an accessible enough method to quantify ventilation that it may encourage researchers, contractors and building owners to perform appropriate ventilation assessments more often and with a good degree of accurateness.