## 2 Methods
### Identification of the Most Common Construction Model in Spain  
To identify the most representative construction model, it is necessary to perform an analysis of the published statistical data. To achieve this, the population and housing census of the National Statistics Institute (INE, Madrid, Spain) was analyzed first. However, the information provided was found to be insufficient, as there are no data related to the characteristics or construction systems of the current housing stock in Spain [60]. For this reason, information from the 2018 Statistical Yearbook [61] and the Building Construction Statistics report 2015-2019 was used [62]. Both documents, edited by the Ministry of Development, offer data based on the municipal licenses granted and compile the most relevant statistical information on the construction activity dedicated to building, in the modalities of: newly built construction, renovation, and total or partial demolition of buildings, and of the evolution and characteristics of the building stock at a national level. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Year, Reference**} & \multirow{2}{*}{**Waste**} & \multirow{2}{*}{**Binder**} & \multirow{2}{*}{**Application**} & \multicolumn{2}{c}{**Thermal Conductivity**} & \multicolumn{1}{c}{**Compressive Strength**} \\  & & & & **[w/mK] (\% of Waste** & **[Mpa] (\% of Waste** & **[Mpa] (\% of Waste** & **[Mpa] \\  & & & & **Addition)** & **Addition)** \\ \hline
2015, [48] & Wheat and barley straw & Gypsum, cement, soil & Bricks & 0.31 (3\% wheat straw) & & - \\
2017, [49] & Rubber & Cement & Masonry units & 0.8 (20\% waste) & 15.4 (20\% rubber) \\  & Sugarcane & & & 0.65 (37\% waste) & 6.7 (37\% rubber) \\
2018, [50] & Bagasse Ash & Clay & Bricks & 0.35 (15\% SBA) & 5.01 (15\% SBA) \\  & Rice Husk Ash & & & 0.37 (15\% RHA) & 5.53 (15\% RHA) \\
2018, [51] & Glass & Clay & Bricks & 0.59 (25\% waste) & 12.56 (25\% glass) \\  & Expanded & & & & \\
2018, [52; 53] & polystyrene & & Plasters, coatings & 0.23 (2\% EPS) & 2.74 (2\% EPS) \\
[52; 53] & Extruded & Gypsum & coatings & 0.29 (2\% XPS) & 5.59 (2\% XPS) \\  & polystyrene & & & & \\  & Expanded & & & & \\
2019, [54] & polystyrene & & & & \\  & Extruded & Gypsum & Plasterboard & 0.16 (3\% EPS + 1\% XPS) & 3.56 (3\% EPS + 1\% XPS) \\  & polystyrene & & & 0.15 (2\% EPS + 3\% XPS) & 3.28 (2\% EPS + 3\% XPS) \\
2019, [55] & Glass & Gypsum & Coatings, & 0.28 (70\% waste) & 8.7 (70\% waste) \\  & & & elements & 0.31 (100\% waste) & 10.2 (100\% waste) \\
2019 [56] & Expanded & & & & \\  & polystyrene & Gypsum & Plasterboard & 0.3 (2\% EPS) & 2.35 (2\% EPS) \\
2020, [57] & Chicken & & & & \\  & feathers & Gypsum & Plasterboard & 0.309 (5\% waste) & - \\  & Ceramics & & & & \\
2020, [58] & Expanded & Gypsum & Blocks & 0.28 (75\% CER + 2/3 & 0.95 (75\% CER + 2/3 & EPS) \\  & polystyrene & & & & EPS) \\
2021, [59] & Granular cork & Cement & Non-load carrying & 0.38 (100\% waste, m3) & - \\  & & & elements & 0.15 (300\% waste, m3 + & - \\  & & & & 3\% slag) & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Previous studies of recycled materials and their thermal characterization. These documents do not have the deficiencies mentioned above and allows to know the mostly used construction models. The percentages shown below were obtained with statistical tables referring to the years 2015 to 2019 [61]. The collected data show that newly built construction works are greater than those of rehabilitation or demolition works. In addition, among the newly constructed buildings, it is observed that residential buildings represent 80% compared to 20% of non-residential buildings. Therefore, it is justified to focus the energy analysis on a new residential building. In general, newly built multi-story buildings for residential use have an average surface area of around 110 m\({}^{2}\).