Prevention of winter mould growth in housing

Abstract

This paper reports on a study that researched the possibility of building passive designs to prevent mould growth in housing in humid and mild winter climatic zones without permanent thermal active controls. This study also investigated indoor relative humidity related to insulation, window cross ventilation, exhaust fan ventilation and temporary heating. The study found that for controlling mould growth on indoor surfaces there are two options available for different climatic conditions and housing designs: a conventional method for buildings designed for permanent thermal active controls and a newer method using passive building design and passive controls to keep the indoor relative humidity under 80%. Implications from the study include the passive prevention of winter mould growth in houses without permanent active thermal controls, insulation levels and thermal resistance, appropriate insulation levels to prevent mould growth, winter daytime cross ventilation, temporary exhaust fan ventilation and temporary heating and their impacts on decreasing mean indoor relative humidity levels and the relative humidity of air near ceilings. Educating occupants on how to ‘drive’ their passive designed house is also critical to prevent mould growth problems.