Risk of indoor condensation related to thermal insulation standards.

Condensation phenomena on internal surfaces of buildings are becoming recurrent eventualities in contemporary buildings, particularly in residential buildings. Despite the general belief, this accumulation of water on walls is not mainly due to mass migration from outdoor to indoor, but to a modification of behavioural approaches of people, especially referring to the preferred air temperature. In addition to new lifestyles of people, air changes established in buildings are strongly affected by new thermal insulation standards that call for more insulated and sealed buildings and, consequently, for less heat loss by ventilation. Both these causes generate a tendency to an increase in the air vapour concentration inside buildings: this turns into a rise of dew point temperature and, finally, in the risk of condensation on colder indoor surfaces of the envelope.