A computer algorithm for predicting infiltration and interroom airflows

This report discusses the extension of an infiltration predicting technique to the prediction of interroom air movements. The airflow through openings is computed from the ASHRAE crack method together with a mass balance in each room. Simultaneous solution of the mass balances in all rooms having both large and small openings is accomplished by a slightly modified Newton's method. A simple theory for two-way flow through large openings is developed from consideration of density differences caused by different temperatures in adjoining rooms. The technique is verified by comparison to published experimental results. The results indicate that the simple model provides reasonable results for complex two-way flows through openings. The model is as accurate as the available data, that is, about +-20%. The airflow algorithm allows infiltration and forced airflows to interact with the doorway flows to provide a more general simulation capability.