Performance evaluation of combined solar chimney and radiative cooling ventilation

Passive cooling is inevitable for buildings to be resilient to global warming. While many forms of passive cooling techniques have been developed, passive radiative cooling (RC), as an emerging technology, is still not widely applied in buildings. Due to current limitations, many proposals for implementing RC in buildings have come up in combination with other passive design strategies. In this study, we propose to combine RC with natural ventilation in the form of a novel RC-enhanced roof solar chimney (SC-RC) ventilation and present an evaluation of its ventilation and thermal performance. A hypothetical room equipped with SC on the sun-facing side of the roof, and RC cavity on the opposite side, was developed. Three different opening configurations were arranged as the case studies, namely 'SC + wall-opening', 'SC-RC', and 'SC-RC + wall-opening'. Computational fluid dynamics (CFD) using ANSYS Fluent 2021 was employed to simulate the case studies. The results indicate that the RC cavity improves the ventilation and cooling performance of the natural ventilation system. In terms of ventilation performance, the 'SC-RC + wall-opening' case is observed to be superior to the conventional 'SC + wall-opening' case, with a daily average ventilation rate of 1.2 ACH daily (required minimum: 0.7 ACH). Likewise, the cooling performance of 'SC-RC' and 'SC-RC + wall-opening' cases are also better than the case without RC cavity.