Indoor air quality in residential buildings: costs, effects and benefits of mechanical ventilation systems

The presence of high levels of urban pollution imposes at the international level the need tothink again about the type of ventilation systems in residential buildings. This has to be donein order to provide a better IAQ level. Natural ventilation cannot guarantee either the correctchange of air inside the buildings or a good IAQ level, as there is no possibility of checkingthe supply and extraction airflow rates in any thermo-hygrometric condition. The high level ofpollution in urban air, due to the traffic, civil and industrial processes of combustion in bigmetropolis, causes a second problem, stronger than the first one: natural ventilation in thesekinds of conditions implies a dangerous and uncontrollable exposure of people to substancesof human origins that are injurious to health. For these reasons the use of mechanicalventilation as a part of the technical equipment of buildings seems to be necessary for thefuture. In this way two effects would be produced at the same moment: the continuousextraction of smells and steam caused by human activities and the supply of treated outdoorair into the civil rooms, to achieve the best control of the quality of the internal air. In thisdirection the revision of international technical laws concerning the ventilation parametersmust be seen and a further acceleration of this process should be provided. In this paper someanalysis about the levels of pollutions in external air of European cities are carried out andconsiderations about costs, effects, benefits, complexity of installation and performances ofmechanical ventilation systems, in terms of IAQ, for residential buildings are developed aswell.