Investigation of the Energy-Saving Potential of Buildings with Radiative Roofs and Low-E Windows in China

This study develops a model for buildings with a cooling roof, walls, and low-emissivity (Low-E) windows. This model is verified through experimental analysis. The cooling demands of standard buildings and cooling buildings are compared, and the energy-saving potentials of cooling buildings are analysed. It is found that compared to standard buildings, cooling buildings exhibit superior cooling performances attributable to the application of cooling materials. Considering Hong Kong’s weather data, the indoor temperature of cooling buildings can be sub-ambient. The cooling demands of cooling buildings are decreased from 75 W/m² to 30 W/m², indicating a 60% energy-saving potential. The nationwide cooling demand for a standard building across China is approximately 95.7 W/m², whereas the nationwide summer average cooling demand for cooling buildings is 52.7 W/m². Moreover, the cooling performance of a cooling roof is adversely affected by hot and humid weather conditions, resulting in lower temperature drops in southern regions compared to northern regions. However, the nationwide temperature drop across China can still be 1.6 °C, demonstrating promising cooling potentials. For the Low-E windows, the temperature can also be sub-ambient, with a nationwide average temperature drop of 1.7 °C. Therefore, the use of Low-E windows across China can also significantly contribute to energy savings for indoor cooling. Overall, the results of this study show that cooling buildings have high energy-saving potential under various climates. The proposed model can provide a reliable tool to facilitate relevant cooling evaluation by stakeholders, thereby benefiting the popularization of this technology.