The dew point is the temperature at which the air is saturated with water vapour. Condensation occurs as soon as the temperature drops at the same vapour pressure, that is to say that when condensation appears on the windows in winter, or when you get out of the shower and the mirrors are steamed up … this means that the dew point has been reached and condensation is taking place.

Nowadays, we place great importance on building insulation, but over-insulating, under-insulating or poor construction details can result in internal condensation.

A dew point calculation is used to determine where condensation may occur, and correct advice can be given to avoid possible mould growth and/or foul odours.

The calculations are based on the international standard EN ISO 13788: “Hygrothermal performance of building components and building elements – Internal surface temperature to avoid critical surface humidity and interstitial condensation – Calculation methods”.