## 2 Materials and Methods
### Key Characteristics of Test Building and Weather Conditions  
A single-family, two-storey, set-on-the-ground building was chosen as the study house. It was made of an innovative hybrid construction, and its total area was 152.4 m\({}^{2}\), including 5.82 m\({}^{2}\) of unconditioned area. The model of this house (Figure 2) with the HVAC system was created with the DesignBuilder energy simulation tool. The external dimensions of the building in the outline were 11.4 m by 10.0 m, and the height was 6.67 m.  
Three types of windows, i.e., double-, triple- and quadruple-glazed, were examined. Details of their thermal and optical parameters are provided in Table 1.  
Examples of the three types of windows that were used in this study are presented in Figure 3. The differences between these glazing technologies are not only in the number of panes but also in the thickness, thermal insulation of the frame and window casing.  
\begin{table}
\begin{tabular}{c c c c} \hline
**Window Parameters** & **Double-Glazed Window** & **Triple-Glazed Window** & **Quadruple-Glazed Window** \\ \hline U-value (ISO 10292 [25], EN 673 [26]) [W/m\({}^{2}\)-K] & 1.634 & 1.072 & 0.806 \\ Total solar transmission (SHGC) [-] & 0.691 & 0.579 & 0.466 \\ Direct solar transmission [-] & 0.624 & 0.458 & 0.338 \\ Light transmission [-] & 0.744 & 0.698 & 0.624 \\ \hline \end{tabular}
\end{table}
Table 1: Basic parameters of the windows used in the analysis.  
Figure 1: Steel frame construction used in hybrid technology (source: Danwood S.A.).  
Figure 3: The three types of windows analysed in this study (_source: photos taken by the author_).  
Figure 2: View of the 3D model of the building and plans of the ground floor (**left**) and first floor (**right**) (_screenshot from DesignBuilder software_).  
As mentioned earlier, the hybrid structure allows for an increase in the glazing area. Table 2 shows the WWR values and the window area in the reference building.  
A case study house was made of partitions with the following heat transfer coefficients, taking into account thermal bridges (BS EN ISO 6946 [27]): external wall--0.105 W/(m\({}^{2}\)-K), flat roof--0.109 W/(m\({}^{2}\)-K), floor on the ground--0.136 W/(m\({}^{2}\)-K), internal floor--0.232 W/(m\({}^{2}\)-K). Due to the innovative nature of the hybrid construction used in this reference house, the manufacturer did not allow the disclosure of the structure of individual partitions.  
Meteorological data were taken from Weather Data by Location [28]. The climatic conditions for the Bialystok location are classified as ASHRAE climate zone--6A and Koppen classification--Dfb. The design temperature used to calculate the heat load of a building is \(-22\)\({}^{\circ}\)C. Kiruna's climatic conditions are more severe, as the temperature assumed for the design of the heating system is \(-29.8\)\({}^{\circ}\)C. This climate zone is classified as Dfb according to Koppen-Geiger and 7A according to ASHRAE.  
The basic weather parameters that characterise both locations, divided into winter, summer and year-round periods, are presented in Table 3.  
The author has also been conducting experimental studies of basic meteorological parameters on the campus of the Bialystok University of Technology since 2014. A detailed discussion of these results and their comparison with the typical meteorological year (TMY) can be found in [29].