## 2 Material and Methods
### The Examined Buildings  
The present study investigated two buildings, including one in the south of Greece (Athens--Climate Zone B) and one in the north of Greece (Thessaloniki--Climate Zone C). The examined buildings are similar, and the only differences are in the construction materials used to follow the Greek regulations (TOTEE--KENAK) [28]. Below, the descriptions of the buildings are given, and the different parameters between them are clearly highlighted. Moreover, it is important to state that the simulation regarding the thermal heating loads calculation was conducted with TRNSYS software [24]. Both buildings had the same dimensions (15 m \(\times\) 15 m \(\times\) 3 m), which included a floor area of 225 m\({}^{2}\) and a volume of 675 m\({}^{3}\). The walls were oriented in four directions, with the south wall including a double-glazed window of 8 m\({}^{2}\). All the external walls, the roof, and the ground came in touch with the outdoor air, and there were no shadings. The buildings each had 4 occupants producing heat of 100 W according to ISO 7730 [30]. Also, the internal gains due to appliances and lighting were selected at 7 W/m\({}^{2}\), which is a typical value for Greek buildings [28]. The infiltration rate and natural ventilation rate were chosen at 1.0 air change per hour, while there was no mechanical ventilation system in the buildings. The thermostat in the heating period was set at 20 \({}^{\circ}\)C. Table 1 includes the composition of the structural components for the building in Athens, while Table 2 gives the respective data for the building in Thessaloniki. The thermal properties of the materials, the U-values, and the thickness of the different materials are listed in Tables 1 and 2. The window (including glazing and frame) in the building of Athens had a total U-value of 2.6 W/m\({}^{2}\) K, and, in Thessaloniki, it was 2.4 W/m\({}^{2}\) K. In both cases, the g-value of the windows was 75%. The heat convection coefficients for the indoor space and the outdoor space were chosen at h\({}_{\text{in}}\) = 7.69 W/m\({}^{2}\) K and h\({}_{\text{out}}\) = 25 W/m\({}^{2}\) K, respectively [28]. At this point, is important to state that the selected values in the present work were selected in order for the studied buildings to be in accordance with Greek legislation. Furthermore, Table 3 summarizes the data of this analysis for the examined buildings. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Structural** & **Materials** & **Thickness (cm)** & **k** & \(\rho\) & **c\({}_{\text{P}}\)** & **U** \\
**Element** & & & **(W/m K)** & **(kg/m\({}^{3}\))** & **(kJ/kgK)** & **(W/m\({}^{2}\) K)** \\ \hline \multirow{2}{*}{Roof} & Concrete & 20 & 2.1 & 2400 & 0.8 & 0.392 \\  & Invalation & 8 & 0.035 & 40 & 0.8 & \\  & Floor & 1.5 & 0.07 & 800 & 1.0 & \\ Ground & Concrete & 25 & 2.1 & 2400 & 0.8 & 0.399 \\  & Invalation & 7 & 0.035 & 40 & 0.8 & \\  & Plaster & 1 & 1.389 & 2000 & 1.0 & \\  & Brick & 10 & 0.889 & 1800 & 1.0 & \\ Wall & Insulation & 6.5 & 0.035 & 40 & 0.8 & 0.441 \\  & Brick & 10 & 0.889 & 1800 & 1.0 & \\  & Plaster & 1 & 1.389 & 2000 & 1.0 & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Structural elements for the building in Athens (Zone B). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Structural** & **Materials** & **Thickness (cm)** & **k** & \(\rho\) & **c\({}_{\text{P}}\)** & **U** \\
**Component** & **Materials** & **Thickness (cm)** & **(W/m K)** & **(kg/m\({}^{3}\))** & **(kJ/kg K)** & **(W/m\({}^{2}\) K)** \\ \hline \multirow{2}{*}{Roof} & Concrete & 25 & 2.1 & 2400 & 0.8 & 0.35 \\  & Invalation & 9 & 0.035 & 40 & 0.8 & 0.35 \\  & Floor & 1.5 & 0.07 & 800 & 1.0 & \\ Ground & Concrete & 25 & 2.1 & 2400 & 0.8 & 0.392 \\  & Invalation & 10 & 0.035 & 40 & 0.8 & \\  & Plaster & 1 & 1.389 & 2000 & 1.0 & \\  & Brick & 10 & 0.889 & 1800 & 1.0 & \\ Wall & Insulation & 7.5 & 0.035 & 40 & 0.8 & 0.298 \\  & Brick & 10 & 0.889 & 1800 & 1.0 & \\  & Plaster & 1 & 1.389 & 2000 & 1.0 & \\ \hline \hline \end{tabular}
\end{table}