## 1 Introduction  
Concerning statistical data at the world level [1] from the International Energy Agency (IEA) source, the growth between the year 2000 to 2016 shows an alarming rise of around 40% in CO\({}_{2}\) emissions (Figure 1). In the last 4 years, a slight reduction in CO\({}_{2}\) in the buildings sector is still playing a crucial role in the global values, knowing that buildings are responsible for 40% of the total CO\({}_{2}\) emissions. Regarding the period from 2000 to the present, the total energy consumption in the European Union (EU) buildings has not changed significantly. However, in Southern Europe, a growth in the energy demand for cooling was observed [1; 2; 3]. Thus, the rise in the energy for cooling demand is expected to be about 150% by 2050 (globally) and between 300 and 600% in developing countries [1]. Pursuing a reduction in the energy demand, while maintaining the thermal comfort of the occupants, the continuous research to find new solution, materials and constructive solutions is necessary in the buildings sector [4]. Focusing on the cooling demand and the overheating risk, the use of phase change materials (PCMs) in constructive solutions has attracted the attention of the research community due to their capacity for energy storage [5], which allows the delay of cooling peak load reducing the maximum and minimum indoor air temperature. Recent researches in this field, particularly aimed at cooling energy reduction focusing on the different systems and strategies incorporating PCM is separated into: microencapsulated PCM inside the material, such as concrete [6; 7; 8]; Trombe solar wall integrating microencapsulated PCM [9]; gypsum [10; 11; 12; 13]; installed into constructive solutions as an independent layer [14; 15]; wallboard and gypsum board [16; 17; 18]; as a shading device [19]; and macro-encapsulated PCM [20; 21; 22]. Moreover, in buildings, the use of PCM could be extended to other interior space envelopes [23], such as suspended ceilings [14; 24], floors [8; 25], windows [19] and active equipment for cooling or heating [26; 27]. Passive techniques have attracted several researchers to fully utilizing natural and hybrid ventilation integrated with the use of PCM components and solutions for overheating reduction [28; 29]. Regarding cooling performance, [PERSON] [29] used the night-time ventilation to decrease the indoor air temperature at night and a layer of PCM in the exterior surface of the constructive solution to decrease the peak of indoor temperature at midday. On the other hand, the widespread application of advanced renewable systems with optimal design led to several developments combining PCM solutions and active systems using machine learning, optimisation as well as artificial intelligence in the design phase [30; 31; 32; 33]. Recently, several authors have focused on the study of new strategies to incorporate PCM into composite foams for applications as insulation layers in the buildings. [PERSON] and [PERSON] [34] performed a critical review regarding the advances in the incorporation of PCM into the polyurethane foams using different methods as well as the potential and economic benefits regarding these PCM applications in buildings. They highlight that the use of PCM in foam composite is associated to a double benefit of providing a thermal constraint to heat flow as well as a thermoregulation effect [35]. Focusing on the trend regarding the use of PCM into polyurethane foams, [PERSON] and other researchers [36; 37; 38] studied the evaluation of thermophysical properties (thermal conductivity) of polyurethane foams with or without microencapsulated PCM in different percentages. In these studies, three different approaches were analysed: the thermal flux meter approach, the guarded hot plate and the transient plane source. Regarding results, they highlight that the use of the microencapsulated PCM in the rigid polyurethane foams leads to an enhanced behaviour of the thermal properties.