Enhanced air flow modelling for AccuRate – A nationwide house energy rating tool in Australia

In this study, an improved multi-zone air flow model has been developed and implemented to replace the existing large opening air flow model MIX2 used in AccuRate's simulation engine. Good agreements have been obtained between the results predicted by the new air flow model and those predicted by analytical solutions for single opening and two-opening cases. A cross-check between MIX2 and the new model has also been carried out. It is shown that the new AccuRate engine converges much better compared to the existing engine with MIX2. In addition to the improved modelling results due to better convergence, the implementation of mass balance with variable density further enhances the performance of the new AccuRate engine which improves the calculation accuracy in modelling natural ventilation and its cooling potential.