## 4 Results and Analysis  
The comparative energy consumption simulation for the RC and CLT office buildings in the five climate zones are presented in Tables 14 and 15. The results indicate that in the Severe Cold Region, the Cold Region and the Hot-Summer Cold-Winter Region, the energy use of the RC framed buildings is approximately 2-4% more than that of the CLT buildings during the operation phase, while in the Temperate and the Hot Summer Warm Winter regions, the energy use for the two structures is similar. The results from Table 15 indicate that the CLT system consumes much less heating energy than the RC buildings in any climate zone. It shows that CLT as an innovative building material has great potential for reducing heating energy. On the contrary, CLT system consumes more energy for cooling than for RC buildings. This result indicates that overheating may occur in CLT buildings due to the lower U values and thermal mass.  
The results show that the average office building energy consumption increased gradually from South to North in China. The average energy consumption in Severe Cold Region is 201.59 KWh/m\({}^{2}\), which is about 200% more than that in Temperate Regions. In the Severe Cold Region and Cold Region, heating energy, which account for approximately 36.8% and 24.5% of the total energy consumption respectively, is the major energy consumption. In the Temperate Region, Hot-Summer Cold-Winter Region and Hot-Summer Warm-Winter Region, cooling energy dominate the majority of the total energy consumption. Cooling energy account for 31.9%, 35.2% and 62.4% of the total energy consumption respectively. The result show that the total energy consumption in the office building with a RC frame and CLT are approximately 201.59 kWh/m\({}^{2}\) and 194.73 kWh/m\({}^{2}\) per annum respectively during the operation phase in the Severe Cold region. These figures reduced to 156.00 kWh/m\({}^{2}\) and 149.67 kWh/m\({}^{2}\) for the Cold region.  
The calculation results echo the outcomes from existing research. [PERSON] pointed out that the building of 30 St Mary Axe, designed by Foster, was expected to consume 140 kWh/m\({}^{2}\) per annum for building's operation [57]. [PERSON] et al. evaluated a large public building in Tianjin, which is located in Cold Region of China, and pointed out that the building consumed 345.0 kWh/m\({}^{2}\) per annum on operation phase [58]. The Australian national average for commercial building energy consumption was 272 \(\pm\) 17 kWh/m\({}^{2}\), with a standard deviation of 128 kWh/m\({}^{2}\) per year [59]. This figure is close to the values of Shenzhen and Shanghai. [PERSON] et al. made simulations to evaluate the cooling load intensity of office buildings in Malaysia. The results showed that the cooling energy consumption was 193 kWh/m\({}^{2}\) per annum [60].  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Buildings**} & \multirow{2}{*}{**Location**} & **Total Energy Consumption (MWh)** & **Heating Energy Consumption (MWh)** & **Cooling Energy Consumption (MWh)** & **Average Value (kWh/m\({}^{2}\))** \\ \hline \multirow{4}{*}{RC Buildings} & Harbin & 5549.83 & 2041.58 & 875.80 & 201.59 \\  & Beijing & 4294.63 & 1051.21 & 1213.26 & 156.00 \\ \cline{1-1}  & Shanghai & 3417.84 & 490.57 & 1202.02 & 124.15 \\ \cline{1-1}  & Shenzhen & 3690.87 & No Heating & 2302.42 & 134.07 \\ \cline{1-1}  & Kunming & 2692.25 & 225.36 & 860.15 & 97.80 \\ \cline{1-1}  & Harbin & 5360.80 & 1797.28 & 904.72 & 194.73 \\ \cline{1-1}  & Beijing & 4120.12 & 818.82 & 1249.29 & 149.67 \\ \cline{1-1}  & Shanghai & 3334.63 & 338.77 & 1228.79 & 121.13 \\ \cline{1-1}  & Shenzhen & 3708.69 & No Heating & 2317.02 & 134.72 \\ \cline{1-1}  & Kunming & 2748.16 & 172.85 & 954.52 & 99.82 \\ \hline \hline \end{tabular}
\end{table}
Table 14: Simulation results of building energy consumption during operation stage per annum.