## 4 Verification of Zero-Energy Building Integrated Planning Methodology
### Verification of Building Orientation and Solar Panel Installation  
While changing the orientation of the building, energy consumption and energy production were estimated. The energy saving rate according to the zero-energy building planning method can be determined by calculating the final energy consumption according to the various directions of the building. Among the DOE reference buildings, a large office building could represent a square-shaped general building, which is suitable for the installation of roof solar panel and BIPV modules. In this study, a large office of DOE was simulated using TRNSYS (Figure 8) with boundary conditions, as shown in Tables 9 and 10. The indoor cooling and heating conditions were set, as shown in Table 11, and the energy consumption of the building was calculated by summing the three items: heating load, cooling load, and latent heat. In particular, the energy consumption was calculated by changing the orientation of the buildings in three regions with different latitudes among a total of 36 orientations at 10-degree intervals from the south direction. The simulation shown in Figure 9 revealed that the energy consumption is the largest in the northeast direction, and regardless of the area where the building is located, the direction with the least energy consumption is south (Figure 10). Therefore, analyzing and selecting the building orientation are necessary to minimize the energy consumption in the zero-energy building planning process. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Building Type**} & \multirow{2}{*}{**Wall Type**} & \multicolumn{2}{c}{**Total Thickness [m]**} & \multicolumn{2}{c}{**U-Value [W/mwK]**} \\ \cline{3-5}  & & **Central** & **Southern** & **Central** & **Southern** \\ \hline \multirow{5}{*}{Large Office} & Adjacent ceiling & 0.358 & 0.330 & 0.220 & 0.260 \\  & Adjacent wall & 0.207 & 0.178 & 0.360 & 0.450 \\ \cline{1-1}  & Exterior roof & 0.480 & 0.420 & 0.150 & 0.180 \\ \cline{1-1}  & Exterior wall & 0.270 & 0.213 & 0.260 & 0.320 \\ \cline{1-1}  & Ground floor & 0.430 & 0.370 & 0.220 & 0.250 \\ \cline{1-1}  & Window & 0.026 & 0.026 & 1.490 & 1.800 \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Properties of large office simulation model. Figure 8: Large office simulation model. Solar panels applied for energy production can be classified into rooftop PV and BIPV modules. The rooftop PV is always installed facing south in the northern hemisphere, and it was assumed to be installed so that the sunlight and panels could be incident at 90 degrees. In addition, it is assumed that BIPV is installed on the outer wall of the building to maintain a 90-degree angle to the ground (Table 12). For solar power generation conditions, Reference Insolation 1000 W/m\({}^{2}\) and NOCT (normal operating solar cell temperature) Insolation 800 W/m\({}^{2}\) were used for solar energy simulation. Energy production was calculated for each of the 36 orientations by adding up the annual production of rooftop PV and BIPV modules. \begin{table}
\begin{tabular}{c c} \hline
**Properties** & **Condition** \\ \hline Heating setting temperature & 20 \({}^{\circ}\)C, Humidity 30\% \\ Cooling setting temperature & 26 \({}^{\circ}\)C \\ Weather data & Representative weather data by statistical analysis of the region from 1981 to 2010 for \\  & 30 years \\ Number of ventilations & 0.5 time/h \\ \hline \end{tabular}
\end{table} 
Table 11: Annual boundary condition of large office simulation model. Figure 10: Energy consumption according to the region. Figure 9: Energy consumption according to the building orientation. The simulation revealed that the energy production decreases in the order of Daejeon, Busan, and Seoul due to the difference in insulation by region. Therefore, in the planning of a zero-energy building, the effect of solar power installation should be reflected depending on the region.