The computer programs published so far have enabled the calculation of airflows at constant temperatures or of air temperatures at constant airflows. The first version of a new microcomputer program has now been developed in which the airflows and temperatures are calculated simultaneously. The time dependency of temperatures, airflows and contaminant concentrations is considered in the calculation method. The source strength of contaminants, outdoor air temperature, wind velocity and direction, convection and radiation loads can all be freely scheduled.
Wind pressure coefficients (Cp values) are among the basic data required for ventilation and air infiltration calculations and modelling. More than two years of systematic wind tunnel testing in ETI of some of the most frequent building shapes has resulted in a database that has been provided with a handling program. This package is available from ETI, for IBM XT/AT and compatible PC's.
The object of this article is to compare the performance of these two flow representations against a small set of measurement data using the concepts outlined in the Air Infiltration and Ventilation Centre's Calculation Techniques Guide.2 A particular aspect of the approach presented is that in each case an identical solution technique, flow network and pressure field has been applied, thus enabling a direct comparison of each of the flow representations to be made. The tests were by no means exhaustive and further evaluation is recommended.
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