Researchers have unveiled a groundbreaking coating that combines aesthetics with functionality, designed to cool buildings and add vibrant colors to urban environments. This innovative technology could reduce reliance on energy-intensive air conditioning units, addressing both global warming and energy crises.
The coating, developed by a team led by Dangyuan Lei from City University of Hong Kong, features a two-layered structure: a white base layer and a top layer enhanced with colored fluorescence. This combination not only provides a visually appealing finish but also cools surfaces by up to 1.5 °C below ambient temperatures. The study detailing this advancement was published in Advanced Optical Materials.
Historically, white surfaces have been used in hot climates for their high solar reflectance, which helps keep buildings cool by reflecting sunlight. The new coating improves upon this by incorporating phosphors and silicon dioxide microspheres. Phosphors absorb sunlight and re-emit it as visible light in specific colors, maintaining high reflectance while providing vibrant hues. Silicon dioxide microspheres, significantly smaller than a pinhead, enhance solar reflectance and optimize the phosphors’ light emission efficiency.
This passive daytime radiative cooling technology cools surfaces without additional energy consumption, making it a sustainable solution for urban heat management. By addressing the urban heat island effect, where city areas experience higher temperatures due to human activities and infrastructure, this coating could reduce heat loads and improve thermal comfort in densely populated areas.
However, the technology currently lacks waterproof properties, which poses a challenge for outdoor use. Despite this, the potential applications are extensive. The coatings can be integrated into existing materials and manufacturing processes, making them suitable for building surfaces, vehicles, and electronics.
As temperatures rise and extreme heat events become more common, innovative solutions like this could offer a cooler, more colorful future.
