## 3 Results and Discussion
### Literature Revision of Materials Applied for Cool Surfaces
#### 3.3.3 PCMs
To compensate for the possible heating load increase in winter while using cool roofs, these materials can prevent the overheating of the roof surface during the summer without increasing the heating load in the winter [86]. As a consequence, they decrease the thermal stress and the annual energy load consumption, in addition to providing thermal inertia for buildings when the melting temperature is optimized [39]. The building energy performance and the thermal comfort could be improved depending on the phase change temperature adopted, according to [PERSON] et al. [87]. Better results were registered for 30 \({}^{\circ}\)C than for 20 \({}^{\circ}\)C.  
The performance of PCM-based surface technology as a UHI mitigation strategy has been evaluated through several studies. For roof application, a cool polyurethane-based membrane reduces the roof-surface temperature and the heat flux through the roof more than a traditional dark bitumen membrane; moreover, the outdoor environmental conditions and the type of PCM host material could influence the performance of the membrane [88]. Similar results were proven using PCM-doped tiles for a cool roof system in simulated summer conditions [40]. In real winter conditions, the use of PCMs maintained a higher indoor temperature than cool paints, and with a low surface temperature reducing the heat penalty [43]. In this sense, several types of PCMs have been tested as dynamic components in buildings in comparison to conventional cool roof materials, showing that their incorporation in the roof materials matrix decreased the heat gain flux by 54%, and registered for various values of albedo compared to cool roof technology, and a lower sensible heat by 40% [16]. PCMs have also been tested for cool pavements. Their use is based on the temperature regulation performance of these materials, which use a lightweight aggregate with a reasonable gradation for better results. The composite PCMs incorporated into the asphalt \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Title of Publ.** & **Authors** & **Journal** & **Year of Publ.** & **Ref.** & **Country of Affiliation** \\ \hline Thermal Performance Test of a Phase-Change-Material Cool Roy System by a Scaled Model. & [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] & _Advances in Civil Engineering_ & 2018 & [86] & Republic of Korea \\ Numerical analysis of phase change materials/wood-plastic composite roof module system for improving thermal performance. & [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] & _Journal of Industrial and Engineering Chemistry_ & 2020 & [87] & United States, Republic Korea \\ How to enhance thermal energy storage effect of PCM in roofs with varying solar reflectance: Experimental and numerical assessment of a new roof system for passive cooling in different climate conditions. & [PERSON], [PERSON], and [PERSON] & _Solar Energy_ & 2019 & [88] & Italy \\ Effects of accelerated weathering on the optical characteristics of reflective coatings for cool pavement. & [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON] & _Solar Energy Materials and Solar Cells_ & 2020 & [89] & China \\ Phase change materials for pavement applications: A review Review of current state of research hazards and commercialization of phase changing materials. & [PERSON], [PERSON], [PERSON] & _Construction and Building Materials_ & 2020 & [90] & India \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Cont. mixtures achieved a satisfactory cooling performance; however, some of them minimized the strength reductions of the mixtures [89]. The incorporation of PCMs in cool surfaces is emerging as a growing field of research because of their ability to restore energy with a minimum change in volume, and without an increase in temperature; however, the encapsulation method may affect their performance and cause leakage [16; 38; 39; 40; 88; 90].