An analysis of the microclimate of Australian wall cavities

The microclimates in wall cavities of brick-veneer houses sited in tropical (Darwin), subtropical (Brisbane) and temperate (Melbourne) zones of Australia were recorded over a complete year. Relative humidity (RH) and temperature in wall cavities of two different orientations and in the house interior were measured every 20 minutes. It is apparent that as well as the daily cycles in temperature and RH, cycles with a range of periods, up to 1 year, occur. Statistical temporal decomposition techniques are used firstly to derive spectral density functions defining the frequency of such cycles, and secondly to construct stochastic models of the RH and temperature variations. In addition, diagrams defining the exceedences of the climatic variables on a seasonal basis are presented. The use of such data for the assessment of material durability and life prediction is outlined.