Thermal performance study of retrofitting existing glazing curtain walls with vacuum glazing in Hong Kong

To reduce buildings’ operational energy consumption, a method of retrofitting the glazing curtain walls of high-rise buildings in Hong Kong with vacuum glazing was proposed. The thermal performance and indoor thermal comfort of the retrofitted and non-retrofitted curtain walls were comparatively studied through outdoor experimental tests. The results show that this energy-saving retrofit method can significantly reduce the internal surface temperature, internal surface heat flux, solar transmittance and solar heat gain coefficient of the curtain wall, while improving indoor thermal comfort levels. Specifically, the average reduction of internal surface heat flux is as high as 81.6%, and the maximum reduction in solar heat gain coefficient is up to 83%. This means that the proposed retrofitted solution can effectively contribute to a reduction in energy use for cooling, and is suitable for using in cities with high cooling demand. The analysis results will provide guidance for energy-saving retrofits of existing curtain walls in high-rise buildings in hot-climate cities, contributing to the achievement of carbon neutrality goals.