Consideration of thermal stratification in multizone models of natural ventilation.

This paper attempts to answer questions like when thermal stratification is important and how to consider it in simple multi-zone models of natural ventilation. Both simple analytical solutions and comparison of CFO and multi-zone analysis suggest that the multi-zone modelling approaches with the assumption of uniform zonal air temperatures can significantly underestimate the neutral levels in buildings with large ventilation openings, indicating that the flow directions through some openings may not be correctly predicted. The predetermined linear vertical air temperature profile method is suggested for modifying existing thermal modelling programs, which may also allow the treatment of surface thermal radiation transfer. An existing multi-zone airflow model, MIX, was modified to include a linear vertical air temperature profile. Future work will include the integration of the airflow and thermal programs considering thermal stratification.