Uncertainty Analysis of Interzonal Airflow Rates by Tracer Gas Methods

Interzonal air movements are important tocharacterize overall ventilation perfosmance ofcomplicated multi-zone indoor spaces. Tracergas techniques are widely used to measureventilation rates or ventilation effectiveness aswell as air movements between indoor spacesusing either a single or multiple tracer gases.This paper compares the tracer gas methods interns of procedures and uncertainties inmeasuring air exchange rates between rooms.Experiments have been conducted in a simpletwo-room model with known airflow rates. In amulti-gas experiment, the concentration decaysof two tracer gases, i.e SF6 and R134a aremeasured after simultaneous injections in eachroom. A single tracer gas method is also appliedby injecting SF6 gas with a time lag betweentwo rooms. The data reduction procedures aredeveloped to obtain the interzonal airflow ratesusing the matrix inversion method. Several datamanipulation procedures are applied, whichinclude data shift, interpolation, and smoothingof concentration data. Uncertainties of thecalculated airflow rates are estimated dependingon the intrinsic behavior of the airflow patternsand the data reduction procedures.