Analysis of errors for a fan-pressurization technique for measuring interzonal air leakage.

The problem of predicting air flows in a multi-zone building has received considerable attention in the past ten years. An important issue identified by this work was the lack of reliable measurements of the flow resistances between the zones of such buildings. This report analyzes the uncertainties associated with 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 multi-family building under typical wind conditions using typical fan pressurization equipment. These simulations indicate that wind-induced uncertainties in the determined leakage parameters do not exceed 10% for windspeeds lower than 5 m/s, but that pressure and flow measurement uncertainties raise leakage parameter uncertainties above 40% at any wind speed. By performing additional simulations, the sensitivity of our results to the subtleties of the measurement protocol and the assumed test conditions are examined. These examinations highlight the importance of using an appropriate reference for the pressure difference across the primary-zone envelope, as well as the importance of improving the precision this measurement.