# Building Energy Retrofit Measures in Hot-Summer-Cold-Winter Climates: A Case Study in Shanghai
## 3 Background Study: Building Energy Consumption and the Climatic Context in Shanghai
### Climate Context  
The climate system in China is complex given that insignificant changes have been observed in the average annual surface temperature despite the significant fluctuations in the average annual temperature of the eight major regions, as shown in Figure 2. According to the China Meteorological Administration, the average annual surface temperature in China has shown a significant upward trend from 1901-2017. From 1951 to 2017, the average annual surface temperature in China increased by 0.24 \({}^{\circ}\)C/decade, and the heating rate was higher than the global average. The difference between the regions is evident. The temperature increase rate in the north is larger than that in the south, and the western region is larger than the east. The Tibet Plateau region has the highest temperature increase rate [24]. In general, the variation between minimum and maximum temperatures in China decreased by 0.24, 0.21 and 0.09 \({}^{\circ}\)C for annual average, January and July, respectively [28]. Consequently, this has affected the design of buildings, particularly the fabric type, in China. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{3}{c}{**Keywords**} \\ \cline{2-4}
**Publisher** & **Climate Change, Buildings, HSCW Climate, Retrofit, Energy, Impact, Sustainable & **Climate Change, Energy Consumption, Shanghai, Development, Hot-Summer-Cold-Winter, Policy, Key Elements** & **Building, Retrofit, Challenges, Methodical Approach, Policy, Key Elements** \\ \hline
**Scientific** & & 1 & 1 \\ \hline
**CNKI** & 1 & 2 & 3 \\ \hline
**JOSRE** & & 1 & 1 \\ \hline
**Total** & 64 & 19 & 21 & 104 \\ \hline \hline \end{tabular}  
Independent publishing: Research institutes (such as Chalmers, Chartered Institution of Building Services Engineers etc.), National Bureau of Statistics, World Business Council for Sustainable Development, JSTOR and Asia Pacific Economic Cooperation.  
\end{table} 
Table 1: _Cont._  
Figure 2: Annual temperature averages [28]. According to the Ministry of Housing and Urban and Rural Development of China, there are five major climate zones in China, with each zone having different building design guidelines [29]. Table 2 and Figure 3 show the climatic classification and characteristics, as well as building design requirements for each region in China. The north of China (north-east (NE), north-west (NW) and part of north-central (NC)) and most parts of Tibet Plateau are classed under a severe cold climate zone. The rest of NC, Tibet Plateau and North China plain are categorized as cold climate zones. East China, south-west (SW) China and south-east (SE) China are in the Hot-Summer-Cold-Winter (HSCW), temperate and Hot-Summer-Warm-Winter (HSWW) climate zones, respectively. In this study, the emphasis is on buildings located in the HSCW climate zone, with two extreme weather conditions within a year. This climate zone was noted to have the most widely ranged climate features which have posed significant technical challenges to building design. A notable city situated in the HSCW climate zone is Shanghai. Shanghai's population was estimated to be 26.32 million in 2018, according to UN world urbanisation prospects. Extending 120 km from south to north, and 100 km from east to west, it covers an area of 6340.5 km\({}^{2}\) and contains 17 local government districts. Shanghai has a humid subtropical climate and experiences four distinct seasons [31]. Building energy consumption in this zone is considerably high due to the fluctuating seasonal climatic conditions. As a result, buildings must meet with anti-overheating, ventilation, shading, and cooling requirements in summer, while anti-cold requirements are also expected in winter [30]. Consequently, this leads to enormous energy consumption for heating and cooling during these extreme conditions. Also, this region is surrounded by several developing provinces such as Jiangsu and Zhejiang, which contributes to high building energy consumption with rapid economic demand.