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.

Within the framework of the Dutch participation in the IEA Annex XIV" Condensation" field experiments have been carried out to study airborne moisture transport in realistic circumstances. The experiments were done in an unoccupied 3-storey dwelling in Leidschendam in the Netherlands. Some of the results will be discussed in this paper.