Investigation of a Fan-Pressurization Technique for Measuring Interzonal Air Leakage

Although the prediction of airflow through single-zone buildings has improved significantly during the past ten years, the more complex problem of predicting airflows in a multizone building has seen relatively little progress. One impediment to the solution of this problem has been the lack of reliable measurements of the flow resistances between the zones of such a building. This report analyzes a fan-pressurization technique for measuring the interzonal leakage (inverse flow resistance) in a multi-zone building. The technique involves two blower doors, one in each of the two zones between which the leakage is being measured. The evaluation of the technique is based upon simulations using MOVECOMP, a multizone infiltration and ventilation simulation program, which is used to determine what data would be recorded when using the procedure in a multifamily building under typical wind conditions. These simulations indicate that wind-induced uncertainties in the determined leakage parameters do not exceed 10% for wind speeds lower than 5 m/s. By performing additional simulations, the effects of wind conditions, building location, and measurement protocol on the uncertainties in the measured leakage parameters are examined in detail. These examinations highlight the importance of using an appropriate reference for the pressure difference across the primary-zone envelope.