Solar chimney combined with underground vent for natural ventilation in energy saving of buildings

Ambient air temperature is always so high in summer that it is very difficult to attain thermal comfort just by direct ventilation. In this paper, the system combining a solar chimney with an underground vent to promote natural cooling is studied through numerical simulation. The analysis is based on six different cases. It is shown that incident solar radiation and solar chimney length are two dominant factors to enhance natural ventilation; the spacing between the top cover and the bottom plate should be 0.3 m in order to maximize mass flow rate. In addition, the height of the underground vent is recommended to be 0.3 m on account of its little effect on enhancing natural ventilation. The length of the underground vent plays an important part in lowering the indoor air temperature, however, it should be determined according to related design criteria. Consequently, this system is an effective method to improve indoor thermal environment in summer.