Natural ventilation design for underground parking garages

Most underground parking garages use mechanical ventilation facilities to remove excessive heat and indoor contaminants and consume significant amounts of energy. Alternatively, underground garages could reduce their electricity consumption by incorporating natural ventilation into their design. However, the effectiveness of different ventilation designs for the natural ventilation of underground space needs to be quantified. This study uses wind tunnel experiments, a Large Eddy Simulation model, and a time-scale analysis to investigate the natural ventilation and the transport of carbon monoxide (CO) in underground garages without mechanical ventilation. The garage with a ramped driveway and a vertical ventilation shaft has the highest ventilation rate and fastest decay rate of CO among the cases being studied. In addition, the simulation results reveal that the windcatcher can enhance natural ventilation when the opening is normal to the wind direction. A garage with only vertical ventilation shafts has the lowest natural ventilation rate. Nonetheless, the ventilation shafts located at the diagonal corners could remove the air contaminants accumulated at the garage corners more effectively. The building above the underground garage could increase the natural ventilation rate by raising the pressure difference between the windward and leeward openings.