Influences of atrium geometry on the lighting and thermal environments in summer: CFD simulation based on-site measurements for validation

Abstract

Atriums have recently been applied with increasing frequency for natural illumination, though they produce a harsh indoor thermal environment. Cooling energy consumption is extremely huge in atriums due to the hot summer in certain regions of China. Accordingly, this paper mainly focused on the ratio of skylight to atrium to optimize the thermal environment without compromising the natural lighting. The study quantitatively analyzed the impacts of two geometric parameters, the area ratio (AR) and section aspect ratio (SAR) of the skylight to the roof, on the lighting and thermal environments of atriums by simulation. These models are calibrated with the data measured in a library in Guangzhou, China, to obtain the most appropriate models and boundary conditions. The SAR range of models was set in SAR<4 to be universal through the investigation of buildings. From the results revealed, the AR is the critical factor affecting the diffuse skylight in atriums, whereas the SAR is not. It was when the AR≥1/5.5 that atriums with square plane can meet the natural lighting requirements. The atrium thermal environment was assessed comprehensively from the aspects of air temperature, surface temperature, and vertical temperature difference. It generally became better as the AR decreases and the SAR increases until to AR<1/5. Thus, the optimal nondimensional combination of the atrium configuration was AR = 1/5 and SAR = 4. The temperature distribution characteristics were explained by the theories of heat pressure and air flow, extending the application scope and prospects of this research.