Ventilation in Buildings: Measurements Techniques, Experimental Results and New Advances

Abstract

reduce the energy consumption used for heating and air conditioning in buildings neglecting the comfort and the indoor air quality of the occupants. This was achieved with an increase in buildings tightness. In the 80s it was realized that the adopted strategy in the last decade to reduce the energy consumption in buildings could lead to the sick building syndrome related with all the disastrous consequences to the occupants. In the 90s the concept of global building design have emerged taking in account the environmental aspects based not only in the equipment performance but also in other quality criteria which leaded to significant technological modifications such as the use of new refrigerants with zero ozone depletion potential and green effect in AVAC systems, /1/. This stated evolution in time of building concept and its rule leaded to its energetic analysis. One of the ways of the energy conservation in buildings goes trough the reduction of the air infiltration, which, in several countries, is the only way to promote the air renewal. As already stated this air renewal cannot go below certain limits as the occupants would be exposed to internal pollutants concentrations far behind of the acceptable limits, /2/. The maintenance of a clean indoor air in buildings depends on the removal capacity to eliminate the internal pollutants generated inside. These pollutants are due either to the internal materials that permanently release VOCs, and either by the physiological processes of the occupants. So the indoor air quality can be increased by several methods: i) promoting the reduction or elimination of the pollutant source; ii) using filters or other kind of material to absorb (eliminate) the pollutants or iii) increasing the airflow inside based either on the air infiltration, natural ventilation or mechanical ventilation. While the implementation of the first method is only possible for some specific cases, e.g., forbidden to smoke inside, the second one is usually too much expansive to be implemented. So the only effective way to achieve a better indoor air quality is by the implementation of the third method by one of the three mechanisms referred and so the necessity to know how to quantify these air exchanges. This work shows how to measure the air infiltration (the most frequent situation in several countries) or natural ventilation in buildings as well as new devices that enables the increase of the air exchange between inside and outside of buildings. When in presence of mechanical ventilation it is also shown the new developed probes that enable the measurement of duct airflows in complex duct nets.