Numerical study of the performance for a curved double-skin façade in summer

Recently, curved double-skin façades (CDSFs) have been increasingly used in buildings due to the advantages of aesthetics and structure. However, existing studies mainly focus on planar double-skin facades (PDSFs) and barely address the thermal and ventilation performance of CDSFs. In this study, the influences of geometric parameters, glass material and solar radiation on the thermal and ventilation performance of the CDSF are studied with a CFD model validated by a reduced-scale experiment. The results show that the optimal cavity gap ranges from 0.75 m to 1 m, and the optimal ellipse aspect ratio is 0.5. Moreover, glass material shows a significant influence on the ventilation performance of the CDSF – an enhancement of 8.20%–21.31% more cavity velocity is found by replacing the clear glass with a low-e glass. Further analysis shows that the ventilation performance is more sensitive to the optical properties of glass material, and a higher absorptivity is more conducive to natural ventilation. Solar radiation – solar radiation intensities and solar incident angles - show predominant impacts on the cavity velocities of CDSFs with non-linear relationships. Because of the surface's non-uniformity distribution of solar radiation, solar radiation shows more impact on the cavity velocities of CDSFs than PDSFs. The influence of solar incident angles is found to be more sensitive, especially in the regions of big solar incident angles - the variation rates of cavity velocities for the CDSF under high solar incident angles (>45°) are much larger than that under low solar incident angles (<45°).