Airtightness and ventilation of social housing in Ireland – A review of field measurements and occupant perspectives pre- and post- retrofit

Airtightness and controlled ventilation are important factors affecting energy use and indoor air quality. Airtightness tests were carried out on nine naturally ventilated social houses in Ireland. Subsequently, four of the houses were retested following energy efficient upgrading. The upgrading largely consisted of improving fabric insulation and where required the mandatory installation of passive wall vents. Interviews were conducted with the occupants to gain their perspectives of airtightness and ventilation in their homes. The occupants of the upgraded houses were interviewed pre- and post- the process.

The paper compares the results obtained to that assumed in the Dwelling Energy Assessment Procedure (DEAP), which is Ireland’s National Methodology for calculating the energy performance of dwellings. The location of the most onerous visible air leakage paths, identified using a smoke pencil are presented.

As an unintentional side-effect, fabric upgrading considerably improved the airtightness of the dwellings.  However, due to lack of cognisance of airtightness principles, simple airtightness techniques which would further improve results were not integrated into the upgrading process. The survey revealed that although occupants understand that ventilation is important, their understanding of required ventilation levels and control is limited. Airtightness levels in one house were high, but the house was under-ventilated resulting in condensation and potential for mould growth on external walls. Whilst a number of houses had considerable levels of uncontrolled infiltration leading to occupant comfort levels being compromised. Overall occupants were happy with the upgrading but had a number of concerns about the newly installed passive vents.

The paper takes a novel approach combining quantitative and qualitative data gaining an insight into occupant attitude and behaviour. The paper highlights the importance airtightness and controlled ventilation in naturally ventilated houses. The paper discusses the potential to reduced air leakage to a level where mechanical ventilation with recovery (MVHR) becomes viable and can be integrated as part of the upgrading process.