## 3 Results
### Model Usefulness
#### 3.3.3 Number of Buildings and Total Floor Area per Energy Performance Class  
Energy classes in Spain show a strong tendency towards class E, which dominates with 81% of buildings and covers the majority of the Spanish residential sector, followed by class F with 7.7%, class D with 5.2%, class G with 4.4%, and the most efficient classes (A, B, and C), which account for 1.4%. These results seem to align with the trends shown in the official report [59], which, although showing more positive results, indicates that 80% of EPCs fall within the three worst letters. The reality of the current building stock, where new buildings must be certified but existing ones only if they are rented or sold, seems to confirm that the percentage of inefficient ratings is much higher.  
Tables 3 and 4 shows the average and total values of NRPEC and GHG emissions per energy class. As shown in Figure 3, since the ranges vary by climate zone and building type, many of the G ratings in the Canary Islands (with lower ranges) cause the average value of the G ratings to be lower than those of classes E and F, which at first glance seems odd.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**GHG Class**} & **Number of Buildings** & **Built Surface Area** & **Average GHG Emissions** & **Total GHG** & **Average NRPEC** & **Total NRPEC** \\  & **Buildings** & **Area** & **kGCO/m2’y** & **Emissions kgCO2/y** & **kWh/m2’y** & **kWh/y** \\ \hline A & 15,474 & 6,214,555 & 9.57 & 51,271,987 & 52.37 & 292,471,440 \\ B & 54,397 & 23,280,581 & 13.97 & 267,932,772 & 68.65 & 1,395,593,965 \\ C & 79,213 & 32,594,351 & 21.39 & 578,346,685 & 103.86 & 2,866,056,800 \\ D & 711,303 & 190,294,671 & 35.00 & 6,116,364,525 & 168.69 & 29,479,214,410 \\ E & 7,124,092 & 2,267,940,997 & 53.94 & 1,034 \(\times\) 10\({}^{11}\) & 248.96 & 4.838E11 \\ F & 458,036 & 79,337,176 & 66.52 & 4,603,973,106 & 290.79 & 20157,771,543 \\ G & 236,598 & 80,209,316 & 39.99 & 2,936,866,706 & 159.86 & 11,674,277,526 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Number of buildings, built surface area, average GHG emissions kgCO2/(m2’y) and total GHG emissions kgCO2/y per GHG emissions class in Spain. NRPEC: non-renewable primary energy consumption, GHG: greenhouse gas emissions.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Energy Class**} & **Number of Buildings** & **Built Surface Area** & **Average NRPEC** & **Total NRPEC** & **Average GHG Emissions** & **Total GHG** \\  & **Buildings** & **Area** & **kWh/m2’y** & **kWh/y** & **Emissions kgCO2/y** \\ \hline A & 10,983 & 3,417,313 & 46.24 & 145,579,347 & 11.11 & 32,216,048 \\ B & 45,363 & 16,755,555 & 64.78 & 946,365,410 & 14.15 & 197,355,494 \\ C & 73,090 & 32,431,374 & 94.31 & 2,514,654,132 & 20.14 & 519,241,248 \\ D & 451,393 & 118,902,156 & 165.95 & 179,566,642,013 & 37.16 & 3,962,400,366 \\ E & 7,054,623 & 2,238,048,969 & 246.58 & 473,078,264,181 & 53.57 & 101,165,823,218 \\ F & 664,791 & 144,744,180 & 275.06 & 34,500,491,341 & 58.56 & 7,302,608,855 \\ G & 378,870 & 125,572,100 & 184.23 & 20,621,312,769 & 41.84 & 4,781,965,848 \\ \hline \hline \end{tabular}
\end{table}
Table 3: Number of buildings, built surface area, average NRPEC kWh/(m2’y) and total NRPEC kWh/y per energy performance class in Spain. NRPEC: non-renewable primary energy consumption, GHG: greenhouse gas emissions.