Automated tracer equipment for air flow studies in buildings.

This paper describes tracer gas methods and equipment developed to measure infiltration and inter-zone air flow rates in New Zealand houses. Air flows in houses have been studied in detail, in order to understand the role of ventilation in controlling indoor moisture, and the role of air flows through the construction cavities in transferring mloisture to parts of the structure most sensitive to moisture. The main technical content of this paper, however, concerns an automated tracer gas detection and delivery system based around a gas chromatograph and an electron capture detector. Constant composition and decay modes of operatmionh ave been automated and the control loops for both modes are illustrated with a flow diagram. Favourable comparisons bet- ween air flows measured and calculated by various methods are presented. Against this background of consistency, a passive technique is shown to give plausible infiltration rates.