Enhancing urban microclimates towards climate-resilient cities: the potential of courtyards

Abstract

The increasingly urgent phenomenon of global warming has a critical epicentre in the topic of urban thermal comfort, which is significantly influenced by the urban heat island effect. In this built environment, creative thinking is required to shape pleasant, healthy, and sustainable microclimates, and not only urban planners and designers but also researchers and software developers are all involved in the search for feasible solutions, tools and opportunities. This chapter evaluates the potential use of one of the most dominant urban configurations in historic Mediterranean cities, the courtyard, as a promising thermal tempering solution to mitigate the impact of climate-related events. The methodology to evaluate the potential of the courtyard microclimate as a climate-responsive strategy follows a top-down approach. Firstly, the relevance of courtyards at city-scale is evaluated in two historic city centres in Spain, Seville and Cordoba. Secondly, six representative courtyards are characterised and monitored to evaluate their thermal benefits. Thirdly, alternatives to improve courtyard performance are discussed and tested in two scenarios. Finally, an urban CFD software to support efficient courtyard design is evaluated in case studies. The results show that this building configuration is highly representative of both historic urban contexts, with approximately 80% of existing plots having inner courtyards. Moreover, the monitored data demonstrates the potential thermal benefits of courtyard microclimates, which can reduce outdoor peak temperature from 6.8 up to 14.3 °C during the hottest days. The analyses show that courtyards with a height/width relation (aspect ratio) above 3 perform better, especially with additional shading devices to reduce solar gains. Finally, the study demonstrated the need to develop more procedures to accurately simulate the specific microclimate of these deep, small-scale spaces as a climate-resilient strategy for buildings and cities, to efficiently mitigate the impact of extreme heat wave events.