## 3 Simulation Methodology
### Validation of the Model  
As a final step in the development of the simulation model to be used in the study, a validation process was briefly carried out to ensure that the model could properly predict the thermal load and energy performance. Actual energy usage of existing typical office buildings was evaluated for comparison with the simulations. According to the Korea Energy Agency (KEA) and Korea Appraisal Board (KAB) database [35], the actual primary energy consumption of the typical office building in the Incheon area is 457-489 kWh/m2. When we performed a simulation using the Incheon weather file, the primary energy consumption was 464.1 kWh/m2, which was within the Korea Energy Agency and Korea Appraisal Board range of 457-489 kWh/m2. First, in this study, the simulation results (CAV system model) confirmed that the base model's primary energy consumption (464.1 kWh/m2a) met the 457-489 kWh/m2a range requirement of the KEA and KAB database [35] for primary energy consumption of general office buildings. Second, the measurement data for selected Seoul metropolitan research buildings and building energy collected by the Korea Agency for Infrastructure Technology Advancement in the MOLIT were compared and verified with publicly available site data [36]. At this time, monthly building energy use was divided into electricity and gas, primary energy requirements were calculated, and error rates were compared. Office buildings in the Seoul metropolitan area with the same building area and HVAC systems were selected and verified. Table 3 summarizes monthly electricity and gas data for seven buildings in the Seoul metropolitan area. The state must primarily provide fossil fuels to meet building energy requirements, so energy requirements were calculated by multiplying the conversion factor by country to apply losses such as power generation and fuel transportation. The primary energy consumption values were calculated using a power conversion factor of 2.75 and a gas conversion factor of 1.1, both of which were set in the Korean building energy efficiency class certification system [37]. Table 4 shows the EnergyPlus simulation results of monthly electricity and gas energy use. Based on Tables 3 and 4, Figure 5 compares the average values of the buildings' electrical measurements with the simulated electrical energy use. The mean bias error (MBE) and coefficient of variation of the root mean squared error (Cv(RMSE)) methods, which are statistical methods mentioned in the M & V Guidelines 3.0 [38], were used to validate the simulation. An MBE range of \(-5\)% to \(5\)% and a Cv(RMSE) of within \(15\)% showed that the model was suitable for analyzing monthly data [38]. The MBE was \(4.31\)% and the Cv(RMSE) was \(8.61\)% when comparing actual and EnergyPlus simulation electrical energy consumption values. Simulation electrical energy values were similar. Both the measured and simulated data exhibited high electrical energy consumption during the summer season (Jun-August) and winter season (December-February), with particularly high peaks in August and December. Intermediate season use was relatively low, with the lowest consumption occurring in May and October. Figure 6 compares the average values of the buildings' gas measurements with the simulated gas energy use. MBE and Cv(RMSE) methods, which are statistical methods mentioned in the M & V Guidelines 3.0, were also used to validate the simulation. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c} \hline \hline \multirow{3}{*}{**Simulation Result**} & \multirow{3}{*}{**Area**} & \multirow{3}{*}{**Energy** (**kWh**)} & \multicolumn{8}{c}{**Monthly Site Energy Consumption**} \\ \cline{3-14}  & & & **Jan.** & **Feb.** & **Mar.** & **Apr.** & **May.** & **Jun.** & **Jul.** & **Aug.** & **Sep.** & **Oct.** & **Nov.** & **Dec.** & **Total** \\ \cline{2-14}  & & & & & & & & & & & & & & & & \\ \cline{2-14}  & & & & & & & & & & & & & & & & \\ \hline \multicolumn{14}{c}{464.1} \\ \hline \hline \end{tabular}
\end{table}