###### Abstract
In order to achieve sustainable growth and development globally, it is necessary to promote the reuse and recycling of materials to create more energy-efficient and sustainable systems. It is important to emphasize that the construction sector on its own is responsible for 36% of all CO\({}_{2}\) emissions into the atmosphere [7]. Given its substantial impact, addressing and mitigating its carbon footprint is essential to continue on the path towards decarbonization. Despite the huge challenge and effort to decarbonize this sector, many researchers are currently addressing this issue [8; 9; 10; 11; 12]. Many authors confirm that renewable energy generation and the application of CE principles lead to a significant reduction of a building's CO\({}_{2}\)-equivalent emissions and its dependence on fossil fuel consumption [13; 14; 15; 16; 17]. The CE provides a comprehensive solution to address these challenges, promoting the reuse and recycling of materials, keeping them as long as possible in the life cycle (LCA) [18]. Its implementation in the building sector will drastically reduce the consumption of natural resources, waste generation, and overall pollutant emissions [19; 20]. The CE covers not only waste management but the entire life cycle of the construction process and the facilities that compose the building. In terms of European circular economy policy, the European Green Deal sets out a new circular economy plan to transform the European Union into a society that opens the way to a greener future by achieving the decarbonization target by 2050 [2; 21; 22]. The new version of the EPBD has recently been approved. It sets out the regulations to be followed as well as the pertinent metric indicators to achieve the decarbonization of the building sector by 2050. Until 2030, building projects will be required to obtain a certificate which guarantees the high efficiency of the building, thus qualifying as an nZEB (near-zero-energy building). This will drastically reduce the building's operating emissions, since renewable energy is used to meet the energy demand [23; 24; 25; 26]. From 2030 onwards, the regulations become even stricter. Buildings must achieve zero greenhouse gas emissions (ZEBs), which requires the calculation of the Global Warming Potential (GWP) for the entire life cycle of the building and not just the operational life cycle [27]. Many researchers are focused on the importance of renewable energy as a way forward to achieve decarbonization targets by reducing operational emissions [28; 29; 30; 31; 32; 33]; however, few emphasize the large impact of building materials on the global GWP [34; 35; 36]. For instance, [PERSON] et al. [37] describe the operational emissions forecasts and the benefits that could be achieved from the decarbonization of electricity based on an LCA analysis. Furthermore, they argue that these benefits will be negated by the rise in embodied emissions associated with construction materials. The overall environmental impact of an nZEB is considerably less than that of a conventional building [38; 39]. It becomes noteworthy that the operational carbon emissions decrease as the energy efficiency of the building increases. However, the percentage of embodied carbon remains notably high for a building with high energy efficiency [40; 41; 42]. In order to reach the European goal of climate neutrality by 2050, it will therefore be necessary to analyze environmental impacts from a holistic perspective, considering both operational and embodied carbon. The UNE-EN 15978 [43] sets the boundaries of the life cycle analysis system. It covers the material production phase (modules A1 to A3), the construction phase (modules A4 and A5), the use phase (modules B1 to B7), the end-of-life phase (modules C1 to C4) and the phase of benefits and burdens due to recycling, recovery, or reuse of materials (module D).