A new ventilation strategy for humidity control in dwellings.

This report presents the results from the registration throughout a month of relative humidity, temperature and outdoor air exchange as well as the concentration of carbon dioxide in each room of an inhabited single family house, in which all rooms are ventilated by a mechanical balanced ventilation system with variable air volume. The outdoor air rate is controlled by the relative humidity, which is kept on a value adequate to reduce the living conditions for house dust mites and prevent condensation on the indoor surfaces of the building. Due to the demand controlled ventilation of each individual room a higher efficiency for reducing water vapors in the dwelling as a whole is likely to be achieved. The results show that it was possible in the context of Danish outdoor climate to maintain humidity conditions that is anticipated to reduce the number of house dust mites in all rooms of a dwelling during more than five months of the year. In all the months the mean daily mechanical ventilation rate is estimated to be 39 % below the level recommended by the N~rdicC omittee on Building Regulations and in the Danish Building Code. At the same time indoor condensation was avoided on poorly insulated surfaces of the building. The concentration of carbon dioxide was below the level recommended in national ventilation standards.