3.1The current situation of energy-saving transformation of urban existing residential area
The construction area of old residential area in 31 provinces was 3.491 billion m2, of which the construction area of old residential area in the severe cold region and cold region was 151,165.9 million m2 before August 2015. After the large-scale application and promotion of project achievements, taking energy saving and emission reduction as an example, according to the conservative calculation, the transformation amount of old residential areas in cold areas is only 10% of the existing old residential area in the severe cold region and cold region, the goal to reduce the building energy consumption ratio set as 10% compared with the guidance value, 600,000 tons of standard coal can be saved annually, 1.5 million tons of CO2 can be reduced, 45,000 tons of SO2 can be reduced, 400,000 tons of carbon dust can be reduced, economic benefits and ecological efficiency can be achieved. Meanwhile, it significantly improves the livability level of existing urban residential areas.
According to the ‘13th Five-Year’plan for renewable energy development [27],issued by the NDRC in December 2016, by 2020, the total annual utilization of renewable energy will be 730 million tce, including the utilization of commercial renewable energy will be 580 million tce. By the end of 2017, the installed capacity of electric power in China was 1.78 billion kilowatts, of which the installed capacity of renewable energy power generation reached about 650 million kilowatts, increasing from 33.1% in 2015 to 36.6% in 2017. Wind power and solar power generation account for more than 10% of the power generation in Inner Mongolia, Gansu, Qinghai and other provinces, becoming an important new power source.
From the Retrofitting of Existing Buildings Yearbook of 2018 [28], the statistics of energy-saving renovation area of existing residential buildings in China during 2017–2018 are shown in Fig. 3 − 1. In order to promote the revolution of energy production and consumption, promote the construction of ecological civilization, and give full play to the role of renewable energy in adjusting the energy structure and protecting the environment, the National Energy Administration organized various regions to prepare the development plan of new energy demonstration cities and new energy application demonstration industrial parks. The number of key development and utilization of renewable energy demonstration projects recommended by new energy demonstration cities in each province is shown in Fig. 3 − 2. In different cities, the advantages of energy resources are different. The renewable energy mainly considered for development includes solar photovoltaic and heat utilization, shallow geothermal energy, biomass energy (waste power generation, etc.), wind power generation, air energy, marine energy, hydropower, etc.
3.2 Energy load of urban existing residential areas
According to the statistical method of China Building Energy Conservation Association for the energy consumption of existing urban residential buildings, the energy consumption of urban residential buildings is mainly composed of the electricity consumption of household appliances and the consumption of natural gas, which is related to the level of urban development, the level of energy technology, the mode and concept of energy consumption of residents. The per capita energy consumption reflects the basic energy consumption of urban residents, which is positively related to the energy consumption of urban residential buildings.
From Fig. 3–3,3–4, it can be seen that the per capita usage of electricity and natural gas is increasing year by year, while the per capita usage of coal is decreasing year by year. From 2009 to now, the per capita use of natural gas has increased by 142.4%. The per capita energy consumption of the whole country and cities is increasing year by year, and the per capita energy consumption of the cities is higher than that of the whole country, but the gap decreases year by year. Until the first time in 2017, the per capita energy consumption of the whole country is higher than that of the cities. It can be seen that energy-saving transformation of urban buildings and utilization of clean energy technology have achieved initial results.
Analysis of Fig. 3–5 shows that coal is the main source of fossil energy consumption in different region, while electricity and natural gas consumption in cold region is the most in each region.
3.3 Regression analysis of urban residential energy consumption
According to the above principle of STIRPAT model, the energy consumption model of urban buildings is established as shown in Fig. 3–6 Regression analysis is carried out with data from 2009 to 2016. Specific data are obtained from CHINA ENERGY STATISTICAL YEARBOOK 2018 [29], Statistical yearbook of urban and rural construction in China 2018.Beijing: China [30], 2012–2018 Annual Research Report on China’s Building Energy Consumption. Beijing: China [31], as shown in Table 3 − 1.
Table 3-1
year
|
Energy consumption of urban residential area (104tce)
|
Total urban population
(104)
|
Gross Domestic Product
(108yuan)
|
Energy consumption per unit of GDP
(104yuan/104tce)
|
Urban per capita energy consumption
(10-4tce)
|
Proportion of clean energy in end energy consumption(%)
|
2009
|
23600
|
64512
|
349081
|
1.16
|
328
|
7.9
|
2010
|
24300
|
66978
|
413030
|
0.88
|
320
|
9
|
2011
|
25300
|
69079
|
489301
|
0.86
|
331
|
9
|
2012
|
26800
|
71182
|
540367
|
0.83
|
344
|
9.9
|
2013
|
28800
|
73111
|
595244
|
0.79
|
357
|
10.7
|
2014
|
30100
|
74916
|
643974
|
0.76
|
364
|
11.7
|
2015
|
32000
|
77116
|
689052
|
0.63
|
377
|
12.3
|
2016
|
33900
|
79298
|
743586
|
0.6
|
395
|
13.4
|
Firstly, multiple linear regression is performed on the data, and the multicollinearity of the data is obtained by Klein discriminant method, which is not explained in detail here. Therefore, multiple linear regression cannot be used, ridge regression is used as mentioned above. Ridge regression is a biased estimation regression method which is specially used in the analysis of collinear data. After running, the ridge trace is shown in Fig. 3–7
According to the value principle of K value (lambda value), this paper takes K value (lambda value) recommended by R software. K = 0.01215678,The regression equation is as follows。
lny = 0.023898lnP + 0.006304lnGDP-0.006651lnEPG + 0.058895lnEP + 0.037602lnCE + 10.235879
where, P: Total urban population, GDP: Gross Domestic Product, EPG: Energy consumption per unit of GDP, EP: Urban per capita energy consumption, CE: Proportion of clean energy in end energy consumption.
The results show that the coefficient of determination R2 (multiple R-squared) is 0.9984 and 0.9950 after correction. The model has high goodness of fit and the model is established.
From the analysis, the result is from large to small in order of their influence: per capita energy consumption, proportion of clean energy in energy terminal consumption, total population, energy consumption per unit of gross product and total population.
3.4. Statistical analysis of clean energy power production by climate division
According to CHINA ENERGY STATISTICAL YEARBOOK 2018[29], the data changes of clean energy in the past three years from 2015 to 2017 in China's primary energy production are deeply explored. Specifically, it includes national power generation, nuclear power, wind power, solar photovoltaic power generation, and natural gas production. Data maps and Line charts are provided to explore the advantages of clean energy resources in various regions, providing support for the next step of alternative application of clean energy in existing urban residential areas.
Electricity generation in each region shows an upward trend year by year. It ranks from high to low as region, hot summer and cold winter region, severe cold region, hot summer and warm winter region and temperate region. Power generation in cold area is the highest, and the average electricity generation in cold region is 2.7 times higher than that in temperate region.
In recent three years, hydropower generation in various regions has tended to grow slowly and steadily. In cold region, hot summer and cold winter region, and severe cold region, hydropower generation is more developed than that in other regions. Yunnan and Sichuan province are located in the upper reaches of the Yangtze River Basin with huge terrain drop, this geographical advantage makes the hydropower development of the two provinces the best.
Nuclear power generation is mainly concentrated in coastal provinces, including Liaoning, Jiangsu, Zhejiang, Fujian, Guangdong, Guangxi and Hainan. From the perspective of climate zoning, nuclear power generation is the most abundant in the hot summer and warm winter region, with an increase of 73.3% from 2015 to 2017.
Wind power generation is mainly concentrated in Inner Mongolia, Xinjiang, Gansu, Ningxia, Hebei, Liaoning, Yunnan and other regions. From the perspective of climate zoning, the wind power generation is the most abundant in severe cold region, from 2015 to 2017, the wind power generation in severe cold region increased by 45.8%.
Inner Mongolia, Xinjiang, Gansu, Ningxia and Qinghai are major provinces of solar power generation. From the perspective of climate division, solar energy resources are abundant in severe cold region and cold region, and from 2015 to 2017, the solar power generation capacity in the cold region increased significantly, with an increase of 261.9% compared with 2015.
From Fig. 3–12 to Fig. 3–19, it can be seen that: 1) the nuclear power generation capacity in hot summer and warm winter region is ahead of other regions, and the power generation capacity is increasing year by year; 2) the wind power generation and solar power generation capacity are strong in severe cold region and cold region, and the power generation capacity is also increasing year by year; 3) the clean energy power generation in each region accounts for a small proportion of the total power generation; 4) the clean energy power generation in each region is positively related to the total power generation.
From Fig. 3–8 and Fig. 3–19, areas with natural gas supply exceeding 150 × 108 m3 in 2017 include Sichuan, Guangdong, Jiangsu and Beijing. Among them, energy departments in Sichuan Province encourage urban residential buildings to use multi-complementary mode of consumption, such as natural gas preferential price can be reduced to 2.2 ~ 2.3 yuan/m3.Natural gas supply in each region shows an upward trend year by year. Natural gas supply in each region ranks from high to low as cold area, cold area, hot summer and cold winter area, hot summer and warm winter region and temperate region; natural gas supply in cold region is the absolute advantage.