Developing coloured photonic material to counteract urban overheating

Urban overheating is a severe environmental concern. Highly absorbent construction materials, such as asphalt and concrete, are one of the primary contributors to urban overheating. The existing urban heat mitigation materials are insufficient to tackle the anticipated intensity of urban overheating. Consequently, developing advanced heat mitigation technologies with superior cooling is critical. Further, modern heat mitigation technologies (based on daytime radiative cooling) rely primarily on highly reflecting and emissive surfaces to limit solar radiation absorption. However, the highly reflective surfaces cause glare, preventing their use on roads and building facades. In addition, applying such non-colored coating in urban settlements is another concern. The research aims to develop colored daytime radiative cooling materials and reduce glare by decreasing surface reflection and compensating it with fluorescent cooling. The empirical investigation tested the performance of green perovskite polymer films with existing daytime radiative coolers (DRC). The outdoor thermal performance was evaluated by combining fluorescent and photonic materials in two different arrangements. The cooling benefits of colored Fluorescent daytime radiative coolers (CFDRC) were evaluated by comparing their surface temperature with that of photonic and nonfluorescent samples. The CFDRC was around 1°C higher than the highly reflective photonic material, and the nonfluorescent – CFDRC maximum surface temperature difference was around 3.5°C.