The influence on ventilation efficiency in typical dwelling with floor-based displacement ventilation

The characteristics of the climate in Taiwan are high temperature and humidity. In order to solvethese basic problems in dwellings, a meteorological station was established in Fulong(northeastern part of Taiwan) to document the detailed microclimatic information of indoor andambient environments during 4 years. According to the hydrodynamics and thermal mechanics,the new ventilation strategy was developed with the thermal mass cooling-down systemconstructed as the porous floor in a full-scale climate chamber. The typical dwelling room is 5.5m (L) 2.9 m (W) 3.05 m (H) with a 0.5 m (H) elevated-floor system. The air intake is locatedunder the elevated floor, and the outlet is the transom window on the other side.The CFD technology was taken to simulate the ventilation efficiency in the study. The factorswe calculated were all set in the same time including pressure drop, velocity, temperature andcarbon dioxide (CO2) concentration. In order to calculate the age of air, the concept ofconcentration decay method was conducted in the unsteady state solution. Hence, the CO2concentration is the tracer gas in the CFD simulation. By validation of full-scaled chamberexperiment, the ke turbulence model of RANS was adopted in all cases. The opening positionsand the opening ratio of the elevated floor were the change factors in this type of displacementventilation. The most operative conclusion to the designer is the porous ratio of the elevatedfloor of about 46%. The ventilation efficiency achieved is 80%, referred to the pistol flow of100%. The air exchange efficiency in a typical dwelling with Floor-Based Natural DisplacementVentilation is higher by 10% than the cross-ventilation through transom windows. Besides, thematerials of the floor with the cooling and dehumidified effects were studied for the integrationsolutions of Indoor Air Quality and thermal comfort in Subtropical Regions.