Natural Ventilation Characteristics and Indoor Air Quality of Buildings.

The importance of natural ventilation, typically restricted to residential buildings application, is rapidly increasing also within the commercial buildings. This is mainly due to the energy savings expected from a reduction of the use of the forced ventilation. Moreover, the remote control of the indoors, provided by means of the intelligent buildings features, allows an easier management of the environmental quality. Furthermore, the indoor air quality is also directly affected by the air exchanges obtained by natural ventilation. Flow rates are strongly influenced by the design characteristics of the openings and by the location of the building with respect to the external winds. On the other hand, the indoor ventilation rates are modified by people who properly operate the window sashes. Using a computer code developed by some of the authors and validated by comparison with experimental data provided by Ispra Joint Research Centre, a comprehensive set of graphs is introduced, in order to check the suitability of the natural ventilation in bringing well conditions of life to the occupants. Fanger's theory based on "olf' and "decipol" methodology has been used for the definition of the indoor air quality levels. Graphs, for assigned geometries of the building and layout of the openings, and for given pollutant sources, give both the proper amount of the flow rate necessary for attaining an assigned percentage of dissatisfied and the flow rates provided by the natural ventilation. By facing these values, it is possible to establish whether the natural ventilation is sufficient or not to ensure the requested air cleanliness.