## 2 Literature Review  
The envelope is the central building system that reacts to local weather conditions. The trends towards intensifying climate change and rising temperatures at a global level, significant challenges for humanity in the following years, will directly impact the performance of buildings and energy consumption throughout their existence. Remodeling the building envelope proves to be an essential strategy from the point of view of several aspects: energy savings, improvement of indoor microclimates, reduction in pollutants in manufacturing, and technical and economic feasibility [19]. Constructive elements with high thermal performance, which comprise the envelope surfaces, guarantee reduced energy consumption with air-conditioning and improved thermal comfort (itefang2014 effect). According to a study from 2022 [11], for the climate projected for the year 2060 in several European cities, an increase between 99 and 380% in the cooling thermal load is estimated, while the opposite behavior can be observed for the heating load, which has an estimated reduction between 38 and 57%, depending on the typology and location. The results demonstrate that zero-energy buildings with lower insulation levels are less sensitive to climate change. Accordingly, buildings in hot climates in southern Italy, within the legal limits for the envelope, will suffer from overheating in the future (2080 projection), leading to disproportionate energy consumption with air-conditioning [12]. Regulatory limits for envelopes have shown trends toward increasing thermal insulation, characterized by low thermal transmittance. Among the solutions that can be implemented in the envelope, it is possible to mention the increase in the thermal mass of the surfaces--improving the energy storage and thermal lag--and the increase in the thermal resistance of the layers of these surfaces--reducing heat transfer by conduction [13]. Although common construction materials can store thermal energy spontaneously as sensible heat, the use of latent heat is considerably more interesting from the point of view of the energy density of the process [14]. Bulk thermal insulators are capable of significantly reducing heat flow; on the other hand, they have little influence on energy storage [15]. In this context, the utilization of phase change materials to store thermal energy through latent heat presents a compelling option for mitigating thermal loads associated with heating and cooling, providing an innovative alternative to traditional envelope construction. Phase change materials have a dynamic behavior, as they can change their physical state at a specific and almost constant operating temperature during the process. Therefore, the passive or active use of PCM, linked to other strategies, can favor their application scenarios. A study from 2021 [16] evaluated the impact of applying PCM on the thermal comfort of a public school with a standardized project in Brazil's bioclimatic regions 1 and 8 [17], also with Curitiba and Rio de Janeiro as representative cities. The buildings did not have mechanical HVAC systems and used natural ventilation to maintain thermal comfort, assessed based on 2017's ASHRAE Standard 55. The authors report that the PCM with a melting temperature of 21 \({}^{\circ}\)C obtained significant results in improving thermal comfort in both cities when applied to the external walls with a thickness of 5 cm. For the city of Rio de Janeiro, the PCM with a melting temperature of 27 \({}^{\circ}\)C also demonstrated a reduction in thermal discomfort hours when applied to the roof, also 5 cm thick. Following this train of thought, phase change materials' reactions are sensitive to climate conditions, although a particular range of operating temperatures can show interesting results in different climates. The authors from a 2022 study [20] applied distinct PCM to buildings with envelopes appropriate to each climate classification, complying with ASHRAE Standard 90.1.