Daylighting performance of atriums in subtropical climate

Design of an atrium aims to provide a good quality of daylighting. This paper deals with a parametric study of geometric effect on the daylighting performance of two typical types of atriums, enclosed and linear, in the subtropical climatic area. A case study of the daylighting of two existing atrium buildings is presented. The software, RADIANCE, is employed to simulate daylighting performance. The simulation results are compared with the field measurement and a 1:100 model atrium to validate the RADIANCE simulation. In the study of the geometric effects on daylighting performance in atriums, three combined geometric parameters, plane aspect ratio (PAR = W/L), section aspect ratio (SAR = H/L) and well index [WI = H(W + L)/2WL], are introduced to determine a proper design geometry. The relationships between the daylight factor (DF is defined as the ratio of the illuminance at a particular point within an enclosure to the simultaneous unobstructed outdoor illuminance under same overcast sky component) and these geometric factors are analysed for the two types of atriums. The results show that, for the enclosed atrium, the DF has an approximately linear relationship with either SAR or WI, while the DF of the linear atrium has an approximately linear correlation with the PAR. The recommended geometric factor may be WI = 1.5 for the enclosed atrium and PAR = 0.5 for the linear atrium if the comfortable DF is required. The results of this will provide a demonstration and general guide for the designers to predict daylighting performance of an atrium building in the subtropical climate region. Copyright The Author 2009. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.