Simulation analysis on synergistic energy-saving effect of building envelope insulation and radiative cooling technology

In recent years, radiative cooling materials (RCMs) have been investigated for application to the external surfaces of buildings, which can effectively reduce the temperature of the external surfaces through their spectral properties, or even make the temperature of the external surfaces lower than that of the internal surfaces. Several studies have evaluated the energy-saving potential of RCMs. However, they only focused on the energy-saving effects of RCMs with a single insulation property applied to the external surfaces of the envelope. There is an essential interaction between RCMs and the thermal insulation performance of the building envelope. This study focuses on the coupled relationship between these two energy-saving measures and proposes a systematic framework for analyzing the combined energy-saving effects of the two measures. Therefore, in this study, taking Guangzhou as an example, using DeST a simulation software embedded with an equivalent sky radiation temperature module, to accurately calculate the radiative heat transfer in different bands of RCMs. Based on the results of large-scale simulations of the simplified model and considering the internal heat density, air conditioning setting temperature, and building floor, this study demonstrated that with the application of RCMs to the external surfaces of the envelop, the thinner the insulation layer, the more profitable it is in terms of energy savings in some cases. The simulation results of the complex building model show that choosing the optimized combination of energy savings can lead to energy savings improvement of 2.88–4.86 kWh/m².