With support from the PolyU Carbon Neutrality Funding Scheme, Prof. Vivien LU Lin, Member of the Otto Poon Charitable Foundation Research Institute for Smart Energy (RISE), Research Institute for Sustainable Urban Development (RISUD) and Research Centre for Resources Engineering towards Carbon Neutrality (RCRE), and Professor in the Department of Building Environment and Energy Engineering, and her research team have integrated the solar-driven adaptive radiative cooling (SARC) coating they developed, with bifacial solar photovoltaics (PV) to achieve synergistic enhancement of thermal management and power generation, transforming buildings from energy consumers into energy harvesters. The team is planning to install bifacial PV panels on the rooftops of the PolyU Kowloon Tong Student Hostel, which is currently under construction. The new coating will be applied to the corresponding area under the rooftop panels, to enhance power generation while radiatively cooling the buildings.
The carbon dots (CDs)-driven photoluminescent radiative cooling nanocoating can be applied not only to building rooftops but also to exterior walls. This novel coating can automatically adjust its absorption and emission of solar and thermal radiation in response to changes in environmental temperature or light conditions, helping to mitigate the heat island effect created by building materials. It uses photoluminescence technology to convert ultraviolet light into visible light, thereby improving the absorption and utilisation of light by PV and increasing PV conversion efficiency.
Compared to traditional coatings, the novel coating can improve effective daytime solar reflectance from 92.5% to 95%, increase the cooling effect by 10% to 20%, and reduce the temperature by up to 25°C when applied to concrete rooftops. This nanocoating is environmentally friendly, water-soluble, free of volatile organic compounds (VOCs), and can be produced in various colours, thus demonstrating significant application potential.
