The recently proposed scalable-manufactured randomized glass-polymer hybrid metamaterial (i.e. metamaterial film) exhibits good energy-saving potential for building applications. The most convenient way to employ this metamaterial film-based radiative cooling is to integrate it with buildings as cool roofs. However, metamaterial film-based radiative cooling is more suitable for buildings with higher roof area to floor area ratios, as this accounts for its relative lower cooling power of 110 W/m ² on a daily average. The prefabricated buildings in China are commonly less than two floors, which are preferable for the application of this metamaterial film-based radiative cooling. To clearly reveal the cooling performance of the metamaterial film-based cool roof (MFCR), a single-floor prefabricated building is modelled in this study, and the energy-saving potential and economic feasibility of the application of the MFCR on the prefabricated building are discussed in detail. When comparing the model in this study with buildings that have the more commonly used shingle roofs or typical white roofs, the annual cooling electricity consumption is reduced by 28.9%–43.0% and 7.8%–12.9%, respectively, for buildings with MFCRs located in five cities in China, each in a different climate zone. Furthermore, the simple payback period for the buildings with MFCRs located in all five climate zones is less than three years compared to the buildings with shingle roofs. Practical application: A recently proposed metamaterial film exhibits good energy-saving potential for building applications. This paper explores the application of this metamaterial film as a cool roof on a low-rise prefabricated building. The analysis of the cooling performance and economic value of this low-rise prefabricated building located in all five climate zones in China provides guiding significance for the application of MFCR.

This paper proposes a temperature-adaptive radiative cooling (TARC) coating with simple preparation, cost effectiveness, and large-scale application based on a thermochromic powder. To determine the energy efficiency of the proposed TARC coating, the heat transfer on the surface of the TARC coating was analyzed. Then, a typical two-story residential building with a roof area of 258.43 m² was modeled using EnergyPlus. Finally, the energy-saving potential and carbon emission reduction resulting from the application of the proposed TARC roof in buildings under different climates in China were discussed. The results showed that the average solar reflectivity under visible light wavelengths (0.38–0.78 μm) decreases from 0.71 to 0.37 when the TARC coating changes from cooling mode to heating mode. Furthermore, energy consumption can be reduced by approximately 17.8–43.0 MJ/m² and 2.0–32.6 MJ/m² for buildings with TARC roofs compared to those with asphalt shingle roofs and passive daytime radiative cooling (PDRC) roofs, respectively. This also leads to reductions in carbon emissions of 9.4–38.0 kgCO₂/m² and 1.0–28.9 kgCO₂/m² for the buildings located in the selected cities. To enhance building energy efficiency, TARC roofs and PDRC roofs are more suitable for use on buildings located in zones with high heating demands and high cooling demands, respectively.

Cool roofs with higher solar reflectance and emittance can effectively reduce building energy consumption. However, it is still limited to use at night on account of the development of roof materials during the past decades. The newly proposed metamaterial-based cool roof (MCR) greatly improves the possibility of the radiative cooling in the daytime. To study the influence of MCR on the energy consumption for the office building, a small single-floor office was adopted to analyse the cooling performance of MCR by using EnergyPlus. In this study, the optimization analysis was conducted based on the proposed dimensionless thermal resistance ( θ_RTR) and roof pitch (Δ). Then the annual electricity saving potential of the office building with MCR was evaluated in details based on the selected cities from all five climate zones in China. The results show that more annual electricity saving can be achieved under the optimized values of θ_R7 = 1.53 and Δ = 20°. Furthermore, more than 15.7% of annual cooling electricity saving can be achieved while the optimized θ_RTR and Δ are applied.

The power of one rack in a data center can be greater than 3 kW, which is released within a relatively small area. However, most of the heat in a data center is released from the electronic chips. Thus, the energy consumption of the air-conditioning system in a data center will be significantly decreased if the heat released by the electronic chips can be reduced directly. Although liquid cooling heat sinks (LCHS) have been demonstrated as an effective way to resolve this problem, the application of LCHS is limited by the uneven cooling distribution on the surface of the electronic chips and the liquid leakage of the LCHS. The constructal law optimizes the design of the pipeline by introducing the freedom of deformation in the fluid geometry to obtain the optimal global performance. In this study, a novel Y-shaped liquid cooling heat sink (YLCHS) was proposed based on the constructal law, in which the cooling water enters the center of the heat sink through the inlet pipe and diffuses into the periphery through the internal Y-shaped microchannels. A numerical simulation was carried out to determine the cooling effect of the YLCHS. Compared to those of the conventional S-shaped liquid cooling heat sink (CSLCHS), the peak surface temperature and the average surface temperature of the electronic chip with YLCHS were decreased by 15.2 °C and 6.3 °C, respectively. Furthermore, the pressure loss of the electronic chip with YLCHS was also reduced by 63.0%.