Upgrading the Urban Fabric: Novel Technologies for Mitigating Extreme Heat in Cities

Urban population density, and its associated infrastructure and resource needs, create an environment unlike any other on Earth. Understanding and managing this “PoliSphere” has never been more urgent as cities become the central stage for confronting global challenges and the changing climate. As global warming alters our weather extremes, exacerbating heat waves, mitigating the urban heat islands that emerge in cities due to their form, function, and fabric is becoming ever more pressing. Fabric, it can be argued, is easier to modify and upgrade than form or function, and as such it has been the main target of heat mitigation efforts. Cool and green solutions have been studied widely and are clearly needed, but they cannot deliver all the cooling cities will require as the planet warms up and heat waves exacerbate. In this talk, we overview the design, modeling, and evaluation of cooling portfolios that include innovative materials and water-based measures for cooling cities. These include retroreflective façades, photovoltaic roofs, phosphorescent pigments, thermochromic roofs, phase change materials, misting, and water-retaining wet walls. We show how these emerging technologies can be effective in developed and developing, or wet and dry cities, making our urban environments more sustainable, resilient, livable, and equitable.