To predict the thermal and indoor air quality performance of vertical displacement ventilation systems using two-zone modeling, it is necessary to account for the different nature of the air flow due to thermal and contaminant mixing within these zones. Two zone modeling of vertical displacement ventilation was performed assuming piston flow in the clean zone, uniform mixing in the dirty zone, and no recirculation between the zones except via heat source plumes.
The role of ventilation in the housing stack is to provide fresh air and to dilute internally-generated pollutants in order to assure adequate indoor air quality. Providing this ventilation service requires energy either directly for moving the air or indirectly for conditioning the outdoor air for thermal comfort. Different kinds of ventilation systems have different energy requirements. Existing dwellings in the United States are ventilated primatiy through leaks in the building shell (i.e., infiltration) rather than by mechanical ventilation systems.
The major objective of the IEA task XIII project is to design and construct low energy dwellings which should be technically and economically realistic in the period 2000-2010. The design criteria for the Belgian dwelling are the following: - low energy demand for heating purposes; - good thermal comfort conditions, as well in winter as in summer with attention to the problem of overheating; - very good airtightness (n50 <= 1 h^-1); - good indoor air quality conditions; - attractive design for majority of potential clients; - only use of realistic technical solutions.
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