Adaptive measures for mitigating urban heat islands: The potential of thermochromic materials to control roofing energy balance

In recent years, the urgent need for reducing building energy consumption has prompted the scientific community to investigate and develop new adaptive materials for the built environment, and to use field monitoring and multiscale advanced modeling for analyzing and improving the urban microclimate conditions using these new materials. In this work, the Princeton Urban Canopy Model (PUCM) is used to investigate the potential of an advanced urban roofing material to counteract urban overheating in summer, while simultaneously taking advantage of solar passive heating in winter. The roofing applications are characterized by an adaptive dynamic temperature-dependent optical behavior. In particular, the effect of thermochromic materials on local energy transport phenomena is assessed and benchmarked against a traditional dark roof and a more common cool roof solution. These materials undergo a rapid albedo increase when the surface temperature exceeds a certain threshold. Results demonstrate that using thermochromic materials produces a smart optical response to local environmental stimuli and allows enhanced shortwave solar reflection in summer conditions, reduced reflected solar fraction in winter, and adaptive properties during transition periods.