The simulation of infiltration rates and air movement in a naturally ventilated industrial building.

This paper describes the application of numerical models to predict the ventilation rate and internal air movement patterns for a naturally ventilated industrial building and compares the results with measured data. Two modelling techniques have been employed. Firstly, a zonal network model (HTBVent), using leakage area data derived from fan pressurisation measurements, was used to predict the time varying ventilation rate in response to variations in wind velocity and internal-external air temperature difference. The results compare well with measurement data (obtained using constant concentration tracer gas techniques) over a wide range of ventilation rates. The results demonstrate the use of zonal models to estimate the thermal benefits of applying sealing measures to building components. Secondly, a computational fluid dynamics (CFD) model (DFS-AIR) was used to predict the ventilation rates and also the internal air movement resulting from natural ventilation, for selected external conditions. The predicted ventilation rates again agree well with measurement data. The resulting air movement patterns can be used to indicate the effectiveness of natural ventilation and the implications for comfort throughout the occupied space. The general conclusion was that these modelling techniques, having been successfully tested against measurement data, can be used in the design of naturally ventilated buildings.