## 3 Methodologies
### Integrated Environmental Solution (IES)--Virtual Environment (VE) Simulation of the Operation Stage
#### 3.2.2 Parameters Setup  
All the parameters setup in the simulation strictly follow the specification Design Standard for Energy Efficiency of Public Buildings (GB 50015), which is issued by the Ministry of Housing and Urban-Rural Development of China. The simulation parameters for the internal gains are tabulated in Table 8. As mentioned above, six categories of energy on operation phase, namely lighting, space heating, space cooling, ventilation, appliance and water heating are simulated.  
(1) Lighting  
The lighting power density is set to be 2-9 W/m\({}^{2}\) according to the different user demand. The calculation time and lighting hourly rate are tabulated in Table 9.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Space** & **Number** & **Per capita Area** & **Lighting Power** & **Appliances Power** \\  & **of People** & **(P/m\({}^{2}\))** & **Density (W/m\({}^{2}\))** & **Density (W/m\({}^{2}\))** \\ \hline Aisle & - & 0 & 4 & 0 \\ Big/Middle office & - & 10 & 9 & 15 \\ Small office & 2 & - & 9 & 15 \\ Meeting room & - & 5–10 & 9 & 15 \\ Tea room & - & 5–10 & 4 & 15 \\ Toilet & - & 0 & 4 & 0 \\ Stair & - & 0 & 2 & 0 \\ Garbage room & - & 0 & 4 & 0 \\ \hline \hline \end{tabular}
\end{table}
Table 8: Simulation parameters of internal gains.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Time** & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** & **9** & **10** & **11** & **12** \\ \hline Rate & 0 & 0 & 0 & 0 & 0 & 0 & 10 & 50 & 95 & 95 & 80 \\ \hline
**Time** & **13** & **14** & **15** & **16** & **17** & **18** & **19** & **20** & **21** & **22** & **23** & **24** \\ \hline Rate & 80 & 95 & 95 & 95 & 95 & 30 & 30 & 0 & 0 & 0 & 0 \\ \hline \hline \end{tabular}
\end{table}
Table 9: Calculation time (h) and lighting hourly rate (%).  
Figure 7: Established model in integrated environmental solution (IES) software platform.  
(2) Space Cooling and Space Heating  
According to the local regulations in China, the indoor temperature is assumed to be controlled between 20 and 26 \({}^{\circ}\)C. The cooling and heating systems are operated automatically when the temperature is not in this range. The energy consumption on holidays is not taken into the consideration. In the Severe Cold Region and Cold Region, the minimum indoor temperature is set to be not lower than 5 \({}^{\circ}\)C on winter holidays to prevent the water pipes from freezing. Taking Beijing as an example, the simulation parameters of space cooling and space heating conditions are tabulated in Tables 10 and 11.  
(3) Ventilation  
Both mechanical ventilation and infiltration are considered in the simulation. The mechanical ventilation operation time is set to be from 07:00-18:00; and infiltration occurs over 24 hours. The mechanical ventilation rate is 5 ach/h and infiltration rate is set at 0.25 ach/h. Taking Beijing as an example, the simulation parameters of ventilation are tabulated in Table 12.  
(4) Appliances  
The lighting power density is set to be 15 W/m\({}^{2}\  
(5) Water Heating  
In the office buildings, the water consumption quota is set to be 10 L for each person every working day. The water heating energy consumption in holidays is not taken into consideration.