Simultaneous calculation of airflows, temperatures and contaminant concentrations in multi-zone buildings.

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. The supply air temperature in mechanical ventilation can be selected as: (1) constant (and scheduled), (2) equal to that of the outdoor air, (3) calculated as the temperature of the mixture of outdoor air and return air. Constant-temperature cases were simulated with the program and the results compared with those obtained from more sophisticated programs. Other cases, with variable temperatures, were compared with the measurements. Good agreement of the results was obtained in all cases. The paper describes the main features of the new program and gives some simulation results.