## 1 Introduction  
The buildings sector used 36% of the total final energy around the world and had 39% of the energy-related CO\({}_{2}\) emissions in 2018 [1]. Because the population is expected to increase by 2.5 billion people by 2050, the energy use in the building sector is set to rise sharply. In warm locations, the energy consumption from air conditioners is high due to the heat flow received by buildings situated in these zones. The building envelope plays a vital role in the thermal interaction between the outdoor and indoor environments. Thus, it is important to minimize the energy gain from the building envelope to avoid the excessive use of electricity for comfort purposes. Today, several technologies are available for building energy retrofitting. There are advanced facades [2], highly insulated windows [3], high insulation levels for roofs and walls [4], reflective coatings [5], phase change materials [6], and well-sealed structures [7], to mention a few. In particular, reflective surfaces are becoming popular for two main reasons. First, the most direct way to reduce the incident solar energy is to reflect it. When new, solar reflective coatings can reflect to the sky up to 90% of the solar energy received by a surface. The second reason is that applying reflective coatings to opaque building components is probably the most simple passive measure because most of these coatingscan be installed in the same way as ordinary paint [8]. These coatings are usually used on building roofs because these components are subject to solar radiation for more hours than other building envelope components [9]. Therefore, when a roof is retrofitted with a reflective coating, it is known as a cool roof. Several researchers around the world have studied the benefits that cool roofs can bring to buildings in different types of climates using a number of approaches. Several experimental studies are available in the literature. For instance, [PERSON] and [PERSON] [10] performed a two-year monitoring campaign to test cool roofs in a residential building located in Italy. The results showed that the cool roof solution reduced the peak temperature of the air in the attic by around 5 \({}^{\circ}\)C. Further, the cool roof provided an overall year-round energy savings that corresponded to 14 kWh/m\({}^{2}\) per year. In China, [PERSON] et al. [11] used a building cell to test different samples of concrete tiles with different solar reflectance. The authors performed a series of experiments and found that the tiles with a reflective coating reached lower interior surface temperatures than the control tile. Moreover, an additional 2-6 \({}^{\circ}\)C cooler temperature around the noon time was achieved by installing at the bottom of the tile a low-emissivity sheathing. [PERSON] et al. [12] evaluated several building roofs with different coatings using two outdoor test cells located in Cuernavaca, Mexico. They showed that in summer, the white roof was 29 \({}^{\circ}\)C cooler than the black roof and just 1.5 \({}^{\circ}\)C warmer than the ambient air. Further, the average daily energy gain of the white roof was 73% less than the black roof. Other studies aiming to investigate the year-round energy savings from cool roofs by using building energy simulation tools are available. [PERSON] [13] studied the influence of solar reflective roofs on the energy consumption of residential buildings of Saudi Arabia. The author used eQuest building simulation software to perform simulations of a building prototype using weather data of 13 major cities of this country. The researcher found that a reflective roof reduced the annual energy consumption required for building cooling by between 110.3 and 181.9 kWh/m\({}^{2}\). The maximum increase in annual energy consumption due to winter heating was only 4.4 kWh/m\({}^{2}\). [PERSON] et al. [14] assessed the effectiveness of cool roofs with optimal insulation levels in different weather conditions worldwide.