Winter air infiltration induced by combined buoyancy and wind forces in large-space buildings

Abstract Excessive winter air infiltration causes high energy consumption for space heating and unsatisfactory indoor environment in large-space buildings, which has not been fully considered in the design and operation stages. This study proposes a simplified method to predict winter air infiltration rate in large-space buildings induced by combined buoyancy and wind forces. The method is based on a theoretical model of indoor space and a CFD simulation of outdoor wind. Compared with a full-scale indoor-outdoor CFD model, the simplified method predicts the air infiltration rate with an average absolute deviation of 5.4% (max: 11.0%). The simplified method is then utilized to discuss the differences between winter air infiltration and natural ventilation in large-space buildings. The average indoor-outdoor temperature difference is only 2.2~4.8 ​K in the natural ventilation condition, while that reaches 10.3~31.6 ​K in the space heating condition. The effective opening area in the natural ventilation condition is 3.5~3.9 times of that in the space heating condition. Therefore, the dominant driven force of buoyancy in the space heating condition results in little possibility of solution multiplicity for winter air infiltration, which ensures the validity of the proposed method.