# Regional Adaptability Analysis of Solar Roof Utilization Technologies in China
## 2 Methodology
### Selection of Typical Buildings  
For each of the 13 zones, a typical building is then determined. The shapes and the functions of the buildings influence their energy consumption and the available roof areas. Different shapes of buildings have different heights and ground floor areas. Firstly, the available roof area for solar utilization systems is dependent on the building height. In other words, for a fixed roof area, the higher the building is, the larger the energy consumption of the building and the less the contribution of the roof to the entire building will be. It should be clarified that the facades of the buildings could also be utilized by solar PV systems. In densely populated urban cities, there will be significant shading on the facade-mounted systems by neighboring buildings. The shading effect is complicated to consider, since it depends on the distance between the buildings, the shape of the buildings, \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multirow{2}{*}{**Zoning**} & \multirow{2}{*}{**Name of City**} & **Solar Radiation** & \multicolumn{2}{c}{**Economic Level**} \\  & & & **Resources** & **Building Climate** & **(Per Capita** \\  & & & **Distribution** & **GDP/RMB)** \\ \hline
1 & A & Shanghai & IV & Hot-summer-and-cold-winter zone & \textgreater{}50,000 \\
2 & B & Chongqing & V & Hot-summer-and-cold-winter zone & 30,000–40,000 \\
3 & C & Guangzhou & IV & Hot-summer-and-warm-winter zone & \textgreater{}50,000 \\
4 & D & Kunming & III & Temperate zone & 10,000–20,000 \\
5 & E & Lijiang & II & Temperate zone & 10,000–20,000 \\
6 & F & Xingyi & IV & Temperate zone & 10,000–20,000 \\
7 & G & Beijing & IV & Cold zone & \textgreater{}50,000 \\
8 & H & Lanzhou & III & Cold zone & 10,000–20,000 \\
9 & I & Lhasa & I & Cold zone & 10,000–20,000 \\
10 & J & Yinchuan & II & Cold zone & 30,000–40,000 \\
11 & K & Urumqi & III &rigid zone & 20,000–30,000 \\
12 & L & Xining & II &rigid zone & 20,000–30,000 \\
13 & M & Changchun & IV &rigid zone & 30,000–40,000 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Typical cities of 13 zones chosen. Figure 4: Zones chosen. and the building heights. In order to avoid over complexity, this paper focuses only on roof areas; therefore, it gives a conservative estimation of the solar utilization potential. In Table 3, the categories of buildings by height in China are listed [35]. The low-rise buildings in China include public buildings with height lower than 24 m and residential building with less than 10 stories, while the super high-rise buildings have a height higher than 100 m.  
Secondly, in the investigations, a near-rectangular building shape is assumed; therefore, the available rooftop area for the solar utilization systems is approximately the same as the ground floor area. The ground floor area, depending on the building height, will be significantly different between different buildings. A survey of approximately 1170 modular buildings was carried out. Based on the statistics of the survey, 100 buildings were identified and analyzed. Among the 100 buildings investigated, 28 buildings are selected as typical buildings, and statistics of the length-width ratio of the buildings is conducted. The results are shown in Figure 5. It is found that 82% buildings have a length-width ratio less than 3, and 86% have a length-width ratio less than 4. Figure 5 shows the relation between the ground floor area and the length-width ratio. It is found that a building with a larger ground floor area typically has a smaller length-width ratio. When the ground floor area exceeds 3000 m\({}^{2}\), the length-width ratio will be lower than 2. The function of the building influences its construction and its energy consumption after commissioning. In China, there are two types of typical civil buildings, namely public buildings and residential buildings.