Assessment of cooling capacity of chimney-enhanced cross-ventilation systems for kindergartens in African cities

This study proposed a novel approach for naturally ventilated buildings to address the challenges of rising temperatures and increased urban heat island effect in African cities. Existing research often overlooks the performance of combined wind and buoyancy-driven systems in the context of climate change. This research introduced a novel chimney-enhanced cross-ventilation configuration that effectively combined both wind and buoyancy effects for optimal performance. By conducting CFD simulations and detailed building energy simulations, the study aimed to quantify the contributions of these driving forces to assess the performance of the proposed innovative ventilation approach in various urban settings, and analyze its adaptability to future climate scenarios. The cross-ventilation system showed superior performance to a single-sided ventilation solution with identical opening areas. The proposed solution achieved airflow rates up to 20 times higher than that of the single-sided alternative, even in urban environments shielded by tall buildings, due to its ability to effectively harness both wind and stack effects. Consequently, this allowed an improvement in thermal comfort, shown by the higher fraction of occupied time within the thermal comfort range, in comparison with single-sided ventilation. Furthermore, the cross-ventilation system could significantly decrease energy use by mechanical cooling systems by up to 31 %, when compared to the single-sided solution. Finally, the use of night cooling further increased energy savings, and significantly reduced peak mechanical cooling thermal loads. Overall, the chimney-enhanced cross-ventilation system is a promising solution for improving indoor environmental quality and energy efficiency in buildings in African cities, since it is particularly well-suited for the climate change-induced challenges in that continent. The findings of this study can inform the design and implementation of sustainable building practices, promoting the adoption of natural ventilation strategies to mitigate the impacts of climate change.