Analysis of Radiative Cooling Performance of Roofs for Different Climatic Conditions by Heat Transfer Modeling

In this research, a mathematical model has been developed to analyze heat transfer processes on roofs with and without radiative cooling. The equations proposed in the heat transfer model have been solved by using Matlab software. The research has evaluated the performance of roofs with radiative cooling for three climatic conditions: cold, hot summer/cold winter, and hot summer/warm winter. From the validation with experimental data, the reliability of the proposed model has been demonstrated, reaching a maximum relative error of 2%. The research shows that the implementation of a radiative cooling layer reduces the average external roof temperature by 22.03%, 16.05%, and 21.84% for cold, hot summer/cold winter, and hot summer/warm winter climates, as well as decreasing the internal roof temperature by 13.58%, 12.56% and 12.51% compared to a conventional roof. The use of radiative cooling on the roofs leads to a reduction in temperature fluctuation throughout the day, achieving a variation of only 2.3 °C. Radiative cooling reduces the annual cooling energy demand by 15.46%. Therefore, the implementation of radiative cooling roofs is important especially in regions such as hot climates. However, this technology is not recommended in cold climates with heating demand. This can cause an 18% increase in heating demand.