SR341 The role of ventilation in managing moisture inside New Zealand homes (2015)

Ventilation, insulation and heating are the key components to ensuring a healthy indoor environment. This work studied airtightness and actual in-service ventilation rates in a variety of modern housing stock.

In-service ventilation rates indicated that, on average, around a third of these homes were underventilated. The airtightness results were also compared to previous work, indicating a clear trend to more airtight buildings. Further work evaluated the consequence of this from the point of view of managing moisture. An experimental facility that had airtightness variables from 1-9 ach @ 50Pa was constructed to evaluate ventilation options at different levels of airtightness.

It was shown there was a reduction in how long moisture remained in the air as ventilation was increased, though the effect was tempered by the sorption into building materials and condensation on surfaces. Our experiments were used to benchmark comprehensive computer models that allow for parametric studies using different input parameters.

Finally, a field study of supply-only ventilation systems was also completed, which gave input into refined control algorithms to minimise the energy impact of ventilation, while in turn maximising their moisture removal efficiency.