New Zealand homes have traditionally been ventilated through open windows and by background infiltration. In recent times, new materials and construction practices have led to more airtight buildings, and open windows are seen more and more as a security risk. These trends call for new ventilation options that are inexpensive and consistent with home security, weathertightness and draught control. This paper is part one of a study of passive ventilation options for NZ homes.
Computational fluid dynamics has been used for assessing the thermal comfort and air quality in an office ventilated with a displacement system for a range of supply air conditions. Thermal comfort is predicted by incorporating Fanger's comfort equations in the airflow model. Indoor air quality is assessed according to the predicted contaminant concentration and local mean age of air. The performance of the displacement ventilation system is then evaluated based on the predicted thermal comfort and indoor air quality.
Organisations in many countries have contributed data to the AIVC to establish a unique collection of numerical data suitable for design purposes and model evaluation. By combining information from these multiple sources, it is possible to consider a far wider range of operating conditions than would be possible by using the results from a single set of measurements alone. The analysis presented in the report is in three sections covering component leakage data, whole building leakage data and wind pressure evaluation.
Natural convection in a thermally driven square cavity filled with air is studied numerically. Since the thermal Rayleigh number of the configuration ranges between 108 and 1012, the flow is turbulent and k-& models are used to predict the behavior of the flow. For this natural convection problem, the viscous sublayer must be discretized and the behavior of the turbulent quantities is damped within this sublayer through low-Reynolds number modelling.
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