Ventilation Measured in the Wall Cavities of High Moisture Risk Buildings

Abstract

New building designs following the New Zealand Building Code Approved Documents complete a 'risk matrix' of climate and building design factors with associated 'risk scores' to guide the selection of wall cladding and cavity design. The risk matrix is briefly described in this paper, along with cavity ventilation results measured with a continuous emission carbon dioxide tracer method. Ventilation rates in a selection of wall cavities are compared with ventilation rates calculated from wind pressures and vent opening sizes. Fan pressurization methods are used to measure the effective leakage areas of infiltration paths because these contribute significantly to ventilation in some cavity types. Acceptable agreement between calculated and measured day average ventilation rates has been achieved in a range of water-managed cavities from drainage planes to drained and ventilated brick veneer cavities with results spanning three orders of magnitude.