# Energy Renovation of Residential Buildings in Hot and
## 3 Results and Discussion
The results summarized in Table 10 for the hot and temperate climate zones together with the optimum insulation thicknesses obtained in [12] to achieve NZEBs in cold climate zones provide an overview of the average thicknesses to be added to the walls, roof, and FFF of the study building for all the winter climate zones and January climate zones in \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Energy Renovation Solution** & **Walls** & **Roof** & **FFF** \\ \hline A3-W-S1-EPS-HC & 0.084 & 0.079 & 0.088 \\ A3-W-S1-MW-HC & 0.106 & 0.100 & 0.109 \\ A3-W-S1-PUR-HC & 0.069 & 0.065 & 0.071 \\ A3-W-S1-XPS-HC & 0.084 & 0.078 & 0.087 \\ A3-W-S2-EPS-HC & 0.084 & 0.079 & 0.088 \\ A3-W-S2-MW-HC & 0.106 & 0.100 & 0.109 \\ A3-W-S2-PUR-HC & 0.069 & 0.065 & 0.071 \\ A3-W-S2-XPS-HC & 0.084 & 0.078 & 0.087 \\ A3-W-S3-MW-HC & 0.091 & 0.086 & 0.094 \\ A3-W-S4-MW-HC & 0.094 & 0.089 & 0.097 \\ A3-W-S4-PUR-HC & 0.061 & 0.057 & 0.064 \\ A3-W *-S1-EPS-HC & 0.084 & 0.079 & 0.088 \\ A3-W *-S1-MW-HC & 0.106 & 0.100 & 0.109 \\ A3-W *-S1-PUR-HC & 0.069 & 0.065 & 0.071 \\ A3-W *-S2-EPS-HC & 0.084 & 0.078 & 0.087 \\ A3-W *-S2-PUR-HC & 0.069 & 0.065 & 0.071 \\ A3-W *-S2-YRS-HC & 0.084 & 0.078 & 0.088 \\ A3-W *-S2-PUR-HC & 0.106 & 0.100 & 0.109 \\ A3-W *-S2-PUR-HC & 0.069 & 0.065 & 0.071 \\ A3-W *-S2-XPS-HC & 0.084 & 0.078 & 0.087 \\ A3-W *-S3-MW-HC & 0.091 & 0.086 & 0.094 \\ A3-W *-S4-MW-HC & 0.094 & 0.089 & 0.097 \\ A3-W *-S4-PUR-HC & 0.061 & 0.057 & 0.064 \\ A4-W-S1-EPS-HC & 0.090 & 0.084 & 0.093 \\ A4-W-S1-MW-H & 0.079 & 0.073 & 0.082 \\ A4-W-S1-MW-HC & 0.112 & 0.107 & 0.115 \\ A4-W-S1-PUR-HC & 0.073 & 0.069 & 0.076 \\ A4-W-S1-XPS-HC & 0.089 & 0.084 & 0.092 \\ A4-W-S2-EPS-HC & 0.090 & 0.084 & 0.093 \\ A4-W-S2-MW-H & 0.079 & 0.073 & 0.082 \\ A4-W-S2-XPS-HC & 0.089 & 0.084 & 0.092 \\ A4-W-S3-EPS-HC & 0.079 & 0.073 & 0.082 \\ A4-W-S3-MW-HC & 0.099 & 0.093 & 0.102 \\ A4-W-S3-PUR-HC & 0.064 & 0.060 & 0.067 \\ A4-W-S3-XPS-HC & 0.078 & 0.073 & 0.081 \\ A4-W-S4-EPS-HC & 0.078 & 0.072 & 0.081 \\ A4-W-S4-MW-HC & 0.098 & 0.092 & 0.101 \\ A4-W-S4-PUR-HC & 0.063 & 0.060 & 0.066 \\ A4-W-S4-XPS-HC & 0.077 & 0.072 & 0.080 \\ B4-W-S1-MW-HC & 0.120 & 0.115 & 0.123 \\ B4-W-S2-MW-HC & 0.118 & 0.111 & 0.115 \\ B4-X-S2-MW-HC & 0.118 & 0.111 & 0.115 \\ C3-Y-S1-MW-HC & 0.123 & 0.110 & 0.119 \\ C3-Y-S2-MW-HC & 0.123 & 0.110 & 0.119 \\ C4-W-S1-MW-HC & 0.134 & 0.129 & 0.138 \\ C4-W-S2-MW-HC & 0.134 & 0.129 & 0.137 \\ C4-X-S1-MW-HC & 0.132 & 0.125 & 0.129 \\ C4-X-S2-MW-HC & 0.132 & 0.125 & 0.129 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Optimum insulation thicknesses to be added to the walls, roof, and FFF, in m, for the energy renovation solutions that would comply with the NZEB requirements. (*) Non-mainland combined climate zone. Spain (Figure 3). To renovate existing buildings within the same winter climate zone, it is necessary to use thicker insulation as the minimum mean temperatures of January increase. This is because the Basic Document Norm on Thermal Conditions in Buildings [36] established the more restrictive thermal transmittances for thermal envelopes, the lower the January temperature, based on which the January climate zone was defined. Table 11 shows the 16 energy renovation solutions that present the best solution from an economic point of view, i.e., the solution with the lowest payback period, in the combined climate zones where an NZEB was not achieved. For climate zones B3, C1, and C2, Table 11 reveals that the best renovated building solutions from an economic point of view are those that use MW as insulation, optimizing the insulation thickness to minimize the total heating and cooling costs, regardless of the system used. Figure 3: Average thicknesses to be added to the walls, roof, and FFF of the study building, in m, for all the winter climate zones (WCZs) and January climate zones (JCZs). Table 12 presents the thermal transmittance of the walls, roof, and FFF, in m, for the energy and environmental impacts obtained for existing buildings in the different combined climate zones using HULC [42].