Evaluating the thermal environment of a large atrium in an office building using computational fluid dynamics

A glass-roofed atrium often results in vertical thermal stratification, significantly affecting the indoor thermal environment. However, detailed studies on the spatial-temporal variations of the thermal environment in complex atriums, particularly under different operational strategies, remain limited. We employed computational fluid dynamics simulations, validated by field measurements, to analyze the atrium thermal environment of a high-rise office building in Xi'an, China. A detailed three-dimensional model of the building was developed, and the transient multi-region solver chtMultiRegionFoam in OpenFOAM was used for numerical simulations, incorporating the finite-volume discrete ordinates radiation model and the k-epsilon turbulence model to account for radiation and ventilation effects. Operational strategies examined included shading, air conditioning, and their combination during summer and air conditioning during winter. Results indicate that (1) combining shading and air conditioning in summer achieved the most significant cooling effect (7.87 °C), while shading alone provides limited cooling (0.33 °C). (2) The highest vertical temperature gradients were 0.096 °C/m and 0.046 °C/m for summer and winter baselines, respectively. Shading reduced the gradients in the upper zone by up to 0.03 °C/m, with minimal impact on the middle and lower zones. Thermal stratification was nearly absent in air-conditioned areas but increased by approximately 0.3 °C/m in non-air-conditioned upper zones. (3) Regression and correlation analyses identified ambient temperature as the most significant factor influencing atrium temperature, followed by height and radiation for baseline cases. Shading strategies effectively reduced the influence of radiation. These findings contribute to developing sustainable operational strategies for large atrium buildings, optimizing thermal comfort and energy efficiency.