Comparison of performances of displacement and mixing ventilations. Part I: thermal comfort

A numerical simulation using a validated Computational Fluid Dynamics (CFD) model of several types of buildings was used to investigate the difference between mixing and displacement ventilation (DV). The comparison of performances of displacement and mixing ventilations (MV) will be reported in two parts, one on thermal comfort and the other one on indoor air quality. This paper, i.e., Part I, compares the performances of floor-supply DV systems with traditional MV systems for offices, classrooms, retail shops and industrial workshops under a wide range of Hong Kong thermal and flow boundary conditions, such as a very high cooling load. Through proper design, DV can maintain a thermally comfortable environment that has a low air velocity, a small temperature difference between the head and ankle level, and a low percentage of dissatisfied people.