Effect of sunken plaza on ventilation performance of underground commercial buildings

In order to overcome the development limitation of large-scale underground commercial buildings (UCBs) caused by mechanical ventilation mode, three large-scale UCBs being built in Guangzhou are taken as prototypes to discuss the interior ventilation of UCBs affected by the location of sunken plaza as a common entrance form of UCBs, with the implementation of hybrid ventilation as a point of penetration. Then, an analytical model with consistency is established through abstracting the prototypes, and the velocity vector distribution of airflow in three model states is calculated via the CFD simulation of wind environment. Moreover, the interior air change rate of the samples is analyzed, and the regional thermal environment is discussed with WeatherTool, which helps to determine an effective domain of natural ventilation that fulfils the temperature and humidity requirements of human being. Simulated results indicate that (1) suitable sunken plaza location and appropriate relative location of sunken plaza to atrium may improve the air speed, airflow uniformity, comfortable sensation and energy efficiency in natural ventilation state; (2) the heat absorption of fundamental parts helps to obtain a suitable air speed of UCBs in Guangzhou area; and (3) in the design of large-scale UCBs, ventilation simulation is necessary and beneficial.