Evaluating the potential of persistent luminescence in counteracting urban overheating

In recent years, the use of numerical simulations to model real atmospheric conditions over cities has become increasingly popular. One of the primary objectives of these models is to assess the efficacy of various strategies for mitigating the Urban Heat Island (UHI) phenomenon. At the same time, researchers have developed and studied new adaptive materials for building applications that aim to reduce buildings' energy consumption and improve urban microclimate conditions, while performing radiative cooling. Among the new generation of passive cooling solutions, persistent luminescent (PL) materials have emerged as a cutting-edge option for energy-saving purposes, owing to their ability to reject the incident solar radiation through both reflection and light emission. Here, the Princeton Urban Canopy Model (PUCM) is used to evaluate the potential of an advanced PL roof coating to counteract urban overheating. The phenomenon of persistent luminescence is modeled for the first time, taking advantage of experimentally obtained parameters coming from previous studies. Results demonstrate how persistent luminescence can effectively mitigate surface overheating reducing the roof's surface temperature and net shortwave radiation up to 1.15 °C and 35 W/m2 respectively, with consequent benefits to the overall energy balance of the envelope. Such results may be further increased with the optimization of PL materials for engineering solutions.