humidity

Air Infiltration in Norwegian buildings has been an unknown parameter. This paper is based on results from measurements in nine different buildings in Norway. 

Demand controlled ventilation systems have recently become an interesting opportunity to achieve acceptable indoor air quality while minimizing energy consumption. Although they are usually designed for buildings showing relevant variations of occupancy (e g, office buildings, schools, etc.), there are now examples of applications also in residential buildings. One example is the passive humidity-controlled ventilation system recently developed in France. This type of installation has been tested in a five- storey apartment building located in Torino, Italy, during the winter 1989.

The ventilation system described here combines a central air shaft in the hall area with a mechanical waste air extraction system in the bathroom and in the kitchen. If there is a large amount of moisture in the dwelling, the volumetric flow of thewaste air fans is increased, the increase being controlled by means of hygrostats. This ventilation system ensures adequate ventilation of the dwelling. In dwellings without a supply air shaft, this hardly applies any more with the installation of windows with very low joint permeability.

As a consequence of measures required for reducing the heating energy consumption in residential buildings , there have been more and more complaints in the last few years on the appearance of mould in dwellings . In most cases, it is retrofitted or renovated old buildings which are affected [1]. Mould growth is frequently the result of a severe reduction in the natural air change rate in old buildings following the installation of airtight windows, while user habits remain the same as before.