Abstract: A large number of single-family and multi-family buildings, managed accommodation facilities and institutional buildings both in Poland and throughout Europe are equipped with a natural ventilation system. The operation of this system depends, among other things, on weather conditions, and the system itself is prone to design and operational errors. The analyses of the functional programme of typical flats in multi-family residential buildings as well as of single-family houses indicate that in certain rooms, such as kitchens and bathrooms, the values of the basic microclimate parameters can differ significantly from the parameters’ values of the remaining parts of the flat or building. Kitchens and bathrooms particularly require appropriate ventilation. In their day-to-day operation, these rooms are exposed to a more elevated level of relative humidity than other rooms in the flat or building. The paper presents the results of the study conducted in autumn and winter in five flats located on different floors in three multi-family buildings in Poland. All the flats under study were fitted with a natural ventilation system with exhaust ducts in their kitchens and bathrooms. The outdoor air was supplied through window vents installed in the window frames in the selected rooms. Special attention was given to the variability in the levels of relative humidity in these rooms. However, the variability in the indoor air temperature as well as the concentration of carbon dioxide were also considered in the analysis. Only buildings with a natural ventilation system and windowless bathrooms were selected for the study. The results of the analysis showed an elevated level of relative humidity persisting in the rooms in focus throughout the entire period of the study. This salient fact should be noted, since the elevated relative humidity levels combined with the relatively high temperature of the indoor air kept in such rooms in winter are conducive to the development of moisture of the partitions, and in extreme cases, to the development of mould fungi on their surface.
DOI 
Web of Science