Nature-based climate adaptation for compact cities: green courtyards as urban cool islands

Abstract

Urban heat island (UHI) and heat waves are two important phenomena that affect city livability and citizen’s health. Most of experts agree that it is necessary an adaptation strategy to climate changes for the whole urban context. Urban Green Infrastructure (UGI) planning can represent the proper tool to pursue this strategy concretely, also in the compact city, but new approaches, based on the environmental process assessment, are necessary. They are based on closed cycles, efficient local resources optimization and emulation of ecological processes. Modeling approach is fundamental to evaluate the benefits of green strategy scenarios and to define urban regenerations adapted to local conditions. This paper proposes a first climatic assessment based on Envi-met management model to analyze summer air temperatures and thermal comfort related to a green (Nature-based) scenario of a typical urban courtyard of Bari city. The climatic differences between actual and post scenario is analyzed in terms of air T decrease and thermal comfort index (PMV). These indicators are then proposed as proxy for local climatic regulation services. It emerges the relevant role of courtyards as Urban Cool Island (UCI) for UHI mitigation and this result gives new strategic importance to these urban structures. Courtyards, often considered marginal spaces, characterize many Italian cities and towns, and they can be redesigned adding an ecological value to compact cities where very few non-urbanized and open spaces still remain.