# Characteristics of Urban Heat Island in China and Its Influences on Building Energy Consumption
## 3 Results and Discussion
### Electricity and Coal Consumption Induced by the Cooling and Heating Load  
Figures 5 and 6 present the simulated value of electricity consumption (Equation (4)) and coal consumption (Equation (5)), respectively, for a typical residential building in different cities across five building climate zones in China. Under the influences of the UHI, the consumption of electricity and coal decreased by 96.7% (29 out of 30) in SCR cities. The electricity consumption can be reduced by 0.5-18.8 kWh/m\({}^{2}\), and the relative change ranges from 0.9% to 41.3%. The corresponding coal consumption can be reduced by 0.2-6.2 kg/m\({}^{2}\). The energy consumption increases only in Naiman city, due to the different characteristics of its UHII. The winter UHII in Naiman city is 0.5 \({}^{\circ}\)C and the summer UHII is 1 \({}^{\circ}\)C, inducing more energy consumption in summer than energy saving in winter. The winter UHII helps to save electricity consumption by 1.28 kWh/m\({}^{2}\) and coal consumption by 0.42 kg/m\({}^{2}\). However, the summer UHII induces more electricity and coal consumption, 1.4 kWh/m\({}^{2}\) and 0.43 kg/m\({}^{2}\), respectively. Therefore, the overall effect of the UHI in Naiman city is to induce more energy consumption, 0.01 kg/m\({}^{2}\) for coal consumption and 0.12 kWh/m\({}^{2}\) for electricity consumption. In CR, 45 out of 74 cities (60.8%) have lower energy consumption in the presence of the UHI. The electricity consumption and coal consumption saving due to the UHI are in the range 0.03-4.5 kWh/m\({}^{2}\) (saving 0.11-14.4%) and 0.04-1.5 kg/m\({}^{2}\) (saving 0.4-14.7%), respectively. In the other 29 cities, the energy consumption was increased by the UHI. The percentage of increase for electricity and coal consumption are around 0.1-20.1% and 0.04-21.7%, respectively.  
The building energy consumption is increased in most HSCVR cities (43 out of 64, 67.2%). The increasing value of electricity consumption and coal consumption are in the order of 0.05-6.2 kWh/m\({}^{2}\) and 0.01-1.9 kg/m\({}^{2}\), respectively, corresponding to the relative change of around 0.1%-22.7%. On the other hand, for the cities with a decreasing trend, the UHI can save electricity consumption by around 0.03-5.8 kWh/m\({}^{2}\) and coal consumption by 0.01-1.8 kg/m\({}^{2}\). The relative change is in the order of 0.1-18.3%. Similarly, most of the cities in HSWWR (15 out of 20, 75%) and MR (7 out of 11, 63.6%) have a higher energy consumption when the UHI is present.  
Figure 4: (**a**) UHII\({}_{SD}\) in typical SCR cities. (**b**) Seasonal mean UHII in typical SCR cities.  
Figure 5: _Cont_.  
Figure 5: Cooling and heating load-related electricity consumption simulated with (**a**) urban air temperature and (**b**) rural air temperature. (**c**) The differences between urban electricity consumption (\(EC_{u}\)) and rural electricity consumption (\(EC_{r}\)) indicate the effect of UHII on electricity consumption in a typical residential building. (**d**) The relative change in electricity consumption due to UHII, i.e., (\(EC_{u}-EC_{r}\))/\(EC_{r}\).  
Figure 6: _Cont._