Assessing convection modelling in building energy simulation models for night cooling

A sensitivity study is conducted with TRNSYS 17 to quantify the influence of different convection correlations during night ventilation on the thermal comfort. Furthermore, three other parameters were varied as well: the air change rate at night, the internal gains, and the accessibility of the thermal mass in the ceiling. The influence of using the Richardson number as correlation selection criteria is investigated. The results show that there is a high risk in overestimating the efficiency of night ventilation, when current assumptions regarding the prevalence of mixed and forced convection regimes are used.