- Email: [email protected]
Building energy use in China: Ceiling and scenario
Energy and Buildings 102 (2015) 307–316
Contents lists available at ScienceDirect
Energy and Buildings journal homepage: www.elsevier.com/locate/enbuild
Building energy use in China: Ceiling and scenario Chen Peng, Da Yan ∗ , Siyue Guo, Shan Hu, Yi Jiang Building Energy Research Center, Tsinghua University, Beijing, China
a r t i c l e
i n f o
Article history: Received 10 March 2015 Received in revised form 28 May 2015 Accepted 29 May 2015 Available online 1 June 2015 Keywords: Building energy use Energy supply CO2 emissions Ceiling
a b s t r a c t With increasing levels of urbanization and a growing economy, total building energy use in China is rapidly increasing. However, energy use must be controlled due to limited energy supply and the goal of lowering carbon emissions. This study tried to define a reasonable limit for total energy use in China, and, more specifically, a target for building energy use. Domestic energy production, energy imports, and the need to reduce CO2 emissions and fossil fuel combustion were considered when analyzing the available energy for China. The current status and future trends of energy use by industry, building, and transportation sectors were analyzed to determine how much energy the building sector can use considering economic growth and improving living conditions. Within the framework of “Ecological civilization,” this study suggests that annual building energy use in China has to be limited to no more than 1 billion tce. © 2015 Elsevier B.V. All rights reserved.
1. Introduction Building energy use in China has been increasing rapidly in recent years. In 2011, the total building energy use was 687 Mtce (million tons of coal equivalent) [1], 1.5 times that of 2000. The total residential electricity use almost tripled from 145 TWh (terawatthours) to 562 TWh [2]. These large increases of building energy use were caused by the rapid increase of building floor space and energy use intensity for all building types. Constructed building floor space was about 3.16 billion m2 in 2011, up from only 1.6 billion m2 in 2000. In addition, more people are moving from rural regions of the country to urban areas. The urbanization rate is expected to increase from 51.3% to 70% by 2030, which means that China’s urban population will increase to more than 300 million [3]. As additional buildings will be built to accommodate these people, energy use will also increase as the demand grows. The ownership rate of domestic appliances and air conditioning units is also rapidly increasing which is reflected in the rapid growth of the energy use [4]. However, building energy use in China continues to remain far below that of developed countries, whether per capita or per square meter. In per capita terms, China’s building energy use was only 1/8 that of the USA and 1/4 that of Japan and the EUG4 countries (United
∗ Corresponding author. Tel.: +86 15910715460. E-mail addresses: [email protected] (C. Peng), [email protected] (D. Yan), [email protected] (S. Guo), [email protected] (S. Hu), [email protected] (Y. Jiang). http://dx.doi.org/10.1016/j.enbuild.2015.05.049 0378-7788/© 2015 Elsevier B.V. All rights reserved.
Kingdom, France, Germany and Italy) in 2012 (Fig. 1) [1,5,6]. With regard to factors that affect building energy use, different usage modes and lifestyles are the main reasons for the differences in energy use intensities [7–9]. Building energy use will increase as the economy develops and people’s living standards improve, which means that usage modes and lifestyles will change. These changes may include an increase of appliance ownership and usage, as well as improvements to the indoor environment. For example, with an ownership rate for air conditioners of 126.8% for urban households, people will be able to install about three air conditioners per household (one air conditioner per room) [2]. The indoor temperature is considered too low during the winter in the Yangtze River basin and too high during the summer in the southern areas of the country. If the per capita energy use would reach the level of the EUG4, China’s building energy use alone would be 2.9 billion tce (tons of coal equivalent), close to China’s total energy use in 2010. If the energy use per capita reached the level of the USA, the building energy use will be more than twice China’s total energy use in 2010. Several institutes are investigating China’s building energy use, including the International Energy Agency (IEA), U.S. Energy Information Administration (EIA), Lawrence Berkeley National Laboratory (LBNL), Energy Research Institute National Development and Reform Commission of China (NDRC), and the Building Energy Research Center of Tsinghua University (BERC), all of which have published reports about building energy use in China. These reports predict that China’s building energy use will increase in the future as shown in Fig. 2, even though opinions about the current situation differ [10,11]. All reports used a bottom-up approach for their
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
Energy intensity per floor space (kgce/(m 2·a))
308
100 90
Russia, 213
80 70
Korea, 59
USA, 1438
60 Canada, 80
Japan, 163
50 40
India, 283
EU4,396
30 20
China, 648
10
Brazil, 49
0 0
1
2 3 4 Energy intensity per capita (tce/(ca·a))
5
6
2. Method
Fig. 1. Building energy use intensities in 2010.
scenario analyses by analyzing the energy demand for each type of end use. However, the obtainability of energy resources in China was not considered. The IEA analysis, which included an effort to reduce CO2 emission (450 Scenario), found that China’s building energy use should not exceed 835 Mtce by 2030. A “total energy use control” plan was announced in former President Hu Jintao’s report at the 18th Party Congress as an important part of the “ecological civilization”, which is one of the five overarching plans for the development of China. It states that there should be a ceiling for energy use and that total energy use should be strongly controlled. With this guiding ideology, the Chinese government published the Energy Development “Twelfth Five Year Plan” at the beginning of 2013, which announced that China would limit total energy use to no more than 4 billion tce by 2015 [12]. This target was set by considering energy security, resources, environment, technologies, and economic factors. The plan also announced that imported oil should contribute no more than 61% to the total oil demand. The total primary energy use will be limited to no more than 4.8 billion tce by 2020 in the “National Climate Change Plan for 2014–2020” which was released in November 2014 by the NDRC [13]. However, if energy supply cannot meet the energy demand, the country’s entire economy will be in danger. China cannot depend on imported energy to support its development, as China is a very large country whose total energy use represents a large part of the global energy use. Thus, China is determined to
Building energy use (Mtce)
1400 1200 1000
IEA, 450 scenario
800 600 400 200
608.2949 995.3917 1271.889
0 2010
2020 EIA
IEA
2030 ERI
achieve its energy conservation targets by controlling total energy use. In general, China’s building energy use is significantly lower than of developed countries. However, driven by social and economic development, the country’s building energy use is growing fast, which has received much attention from academia and government. If the increase in building energy use continues too rapidly, the environment and the economy will be adversely affected. Most existing research has focused on energy use forecasts and carbon emissions reductions, but there have been few studies of China’s energy supply. Different features of China’s building energy use also have to be carefully considered since developments of China’s building sector are quite different from those in other countries. This study presents a method to predict the ceiling of Chinese building energy use. The model describes each type of building energy use based on BERC’s CBEM (China Building Energy Model) and current building energy use characteristics.
LBNL
Fig. 2. Predicted future building energy use in China. Note: 1. Biomass energy was not included; 2. Different energy policies were considered in the IEA scenarios and different energy prices were considered in the EIA scenario.
As mentioned in the introduction, there have been various scenario analyses of China’s building energy use. However, there has been little consideration of energy use constraints such as limited energy reserves, which may present significant limitations. At the same time, China’s building energy use will differ from that of developed countries due to its dual urban–rural structure and large amount of building floor space with district heating systems in northern urban areas [1]. This study uses a constraint model for building energy use and the national building energy use model (CBEM) developed by THUBERC to predict how building energy use can be limited to a predetermined ceiling. 2.1. Energy use constraint analysis model Energy use is limited by the total energy supply and requirements of CO2 emission reductions. Combined energy resources include fossil fuels, renewable energy resources, and nuclear energy, with all three categories being limited by reserves, technical limitations, and environmental and economic factors. Total energy supply from both domestic and foreign sources cannot increase indefinitely. In addition, fossil fuel usage must be restricted to limit climate change [14]. For these reasons, China’s energy use has to be limited to a predetermined ceiling both for total energy use and energy use of each sector, including industry, buildings, and transportation. Each of these sectors will see growing energy demand in the future. The energy use constraint analysis model is described in Fig. 3. Total energy use is limited by energy supply and CO2 emissions. Domestic and imported energy supplies and energy types must be considered when analyzing energy supply limitations. The current fossil fuel energy supply structure and CO2 emissions are references for CO2 emission limitations. On the other hand, economic and social development will require increasing industrial, building, and transportation energy supply as China develops. As the manufacturing industry is China’s economic pillar, it is difficult to reduce industrial energy use. Increasing travel and car ownership rates are the main drivers for transportation energy use. The drivers for building energy use include population (total population and urbanization rate), economic growth, building floor space, and the culture of energy consumption. Building energy use must be carefully assigned if there is a ceiling on total energy use. Otherwise, any economic and social development will be severely affected. Finding the ceiling for building energy use requires a large amount of data on energy supply and CO2 emissions. China’s
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
309
Fig. 3. Maximum energy use model.
current status and the situation of some of the developed countries were considered when analyzing the demand of industrial and transportation energy use.
2.2. CBEM methodology Analysis of building energy demand depends on current characteristics, including total energy use as well as energy type and purpose. However, the National Bureau of Statistics does not have enough data to clearly understand the building energy use. Thus, an energy use model or energy data analysis tools are needed. As mentioned in the introduction, there have been several studies of Chinese building energy use. Tsinghua University developed the China Building Energy Model in 2009 [15]. This model is being updated to describe the national building energy use characteristics. This model uses a bottom-up method that considers each kind of end use including space heating and cooling, lighting, water heating, appliances, and cooking as shown in Fig. 4. Since climates vary significantly from north to south, the country is divided into five climate zones when considering energy use for heating and cooling. The CBEM uses a different building energy use classifications than most other studies. In most energy use studies, the building energy use was divided into a residential sector and a service sector (or commercial sector). However, building energy use characteristics in China are different from those in other countries.
Building Energy Use
First, there are large district space heating systems in northern urban China. Space heating regulations put in place since the 1950s have created centrally controlled district heating systems, which supply space heating throughout the entire heating season. It was found that over 80% of the building floor area in northern urban regions is supported by district space heating [16]. Few other countries have such large-scale district space heating systems, which often supply tens of thousands or even millions of square meters with heat. Operating time and supplied heat of district space heating systems are controlled by heating companies, which differ with regard to the way they use the decentralized space heating systems. If energy conservation is the goal, more attention has to be paid to the energy efficiency of the heat supply source and to heat loss during the distribution process in addition to the performance of the building envelope. It is apparent that the energy use mode and approach to energy conservation with regard to district space heating are quite different from other kinds of end use. In addition, the energy use for space heating in the northern urban areas is much higher than in the Yangtze River basin, which also experiences cold winter temperatures. However, these energy use differences are not just caused by differences in climate, but mainly by different space heating systems and usage patterns. Second, as China is a developing country, there are significant differences in residential building energy use between urban and rural areas due to differences in lifestyle, income, fuel types, building types, and so on. Farmers build their own houses, while
Population
Floor Space
Urban
Space Heating in North Urban China
Heating
Severe Cold
Commercial and Public buildings (excl. SHNUC)
Cooling
Cold
Hot Water
Hot Summer and Cold Winter
Rural
Urban Residential buil dings (excl. SHNUC)
Appliances / Other
Hot Summer and Warm Winter
Households
Rural Residential buildings
Cooking
Lighting
Temperate
Fig. 4. Structure of the CBEM. Note: The dashed line indicates that energy use for heating is only considered for the Hot Summer and Cold Winter Climate zone.
310
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
Energy Intensity
Corrceon
Floor area and household
Energy balance from NBS annual data
Energy calculaon
No
Verificaon Yes China building Energy use Fig. 5. Flow chart of CBEM.
houses in urban areas mainly built by real estate developers. In addition, most houses in rural areas are single-family units, while most houses in urban areas are multi-family units, including many high-rise residential buildings. Accordingly, building energy conservation policies have to address these differences in energy use between urban and rural areas. Therefore, building energy use in China should be divided into four subsectors to analyze energy use trends and future requirements for each sector. The four subsectors are Space Heating in Northern Urban China (abbr. SHNUC), Commercial and Public buildings (excl. SHNUC) (abbr. C&P excl. SHNUC), Urban Residential buildings (excl. SHNUC) (abbr. UR excl. SHNUC) and Rural Residential buildings (abbr. RR). Model inputs include energy intensity, population, number of households, and floor area. The energy intensity for each kind of building was derived from a large-scale survey and case study that has been conducted since 2007. For SHUNC, heating systems of more than 10 cities were analyzed as part of this study. For C&P excl. SHNUC, we had survey data and measurements conducted in different climate zones for hundreds of buildings. For UR excl. SHNUC, we had access to about 20,000 questionnaires about household energy use as well as about 150 case studies, covering all climate zones. For RR, we had access to about 10,000 questionnaires from across the country. Population and household data were taken from the Statistical Yearbook of the Republic of China. The floor area data are based on the statistical yearbook, related reports, and our own survey. Using these data, the total energy use of the building sector in China can be calculated. Then, the National Bureau of Statistics’ energy balance data were used as the constraint on the total building energy use calculated by CBEM, to verify the model [16]. Fig. 5 shows a flow chart of the model. As shown in Fig. 6, each subsector’s energy use accounted for about a quarter of the total building energy use in China in 2011
Fig. 7. National energy use by fuel type.
[1]. Fuel types and end uses for each subsector were also calculated for data analysis. This study combines investigations from 2008 to 2013 to predict the ceiling of energy use and a reasonable range for future energy use by the building sector. Energy conservation targets are then recommended based on the current characteristics for each subsector. 3. Results – energy use ceiling for China The total energy use in China is rapidly increasing due to social and economic development. Fig. 7 illustrates the increasing trend for total energy use from 1978 to 2011. It can be seen that the national energy use increased rapidly after 2000. From 2001 to 2011, energy use increased from 1.5 billion tce to 3.48 billion tce, an increase of 8.8% per year. Fossil fuels accounted for about 92% of the total energy use in 2011 with coal as the main energy source, accounting for 68.4%. Hydroelectric, wind, and nuclear energy accounted for only 8%. Fossil fuels such as coal are widely used in China because of abundant reserves and low extraction costs. Coal is the main fuel for electricity generation and is widely used for manufacturing (e.g., for steel and cement production) and district heating. Oil is mainly used for transportation, with natural gas also used for electricity generation, space heating, and cooking. China has paid much attention to renewable energy development with a number of hydropower plants. Solar collectors are also widely used for water heating. However, little electricity is generated from photovoltaic or wind power systems due to the non-continuous availability of these resources (wind and solar) and non-uniform distribution [17,18]. The amount and structure of energy use are restricted by the energy supply characteristics. In addition, CO2 emissions must be considered when using fossil fuels. This section analyzes the ceiling for energy use based on these two considerations. 3.1. The ceiling for total energy use
Fig. 6. Building energy use in China in 2011.
3.1.1. Upper limits of energy supply The total energy supply includes domestic energy production and imported energy. In 2011, the total domestic energy production was 3.18 billion tce with imports of 0.62 billion tce, or 16% of the total energy supply [4]. Domestic energy production included fossil fuels, renewable energy sources, and nuclear energy. China has an abundant supply of coal, which accounted for 77.8% of the total energy production in 2011, with oil and gas accounting for 9.1% and 4.3%, respectively. Energy supplied from hydro, nuclear, and wind power accounted for 8.8% of the domestic energy production.
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
311
Fig. 8. Fossil fuels reserves in 2011.
Energy production is restricted by energy reserves, production capabilities, safety, and economics. Although China has large reserves of fossil fuels, the per capita quantity is lower than in other countries, due to its large population (about 1.35 billion people in 2012). As shown in Fig. 8, the per capita coal, oil, and gas reserves are only 2/3, 1/14, and 1/9 of the world average, respectively [19,20]. China has abundant coal reserves, but production is limited by safety considerations. The death rate per million tons of coal produced is about 10 times that of the developed countries [21]. In addition, the coal producing areas are mainly in the northern and western parts of China, which results in high coal transportation costs. At the same time, coal combustion is causing serious environmental pollution. Therefore, a further increase in the use of coal is not tenable and the Chinese government has determined to limit the usage of coal to no more than 4.2 billion tons per year [13]. Chinese oil and natural gas reserves are very limited. Natural gas occurs mainly in western part of China and the Chinese Academy of Engineering (CAE) noted that natural gas production could not exceed 250 billion m3 per year, with a current production of 100 billion m3 per year. In addition, oil production cannot be easily increased without the discovery of new oil fields. In general, fossil fuel production is limited by reserves, the cost of production and transportation, production capabilities, and safety, capping the supply of fossil fuel at around 2.75 billion tce. Renewable energy sources include hydro, wind, solar, and biomass. The hydro, wind, and biomass energy source are mainly located in western China, while the energy demand is greatest in eastern China. Thus, transportation is expensive, which restricts the use of these energy sources. New hydropower plants must consider relocation of people living in the reservoir area and
environmental disruption, in addition to the limited availability of hydropower resources. The Three Gorges hydroelectric power station is China’s largest hydropower station and generated 98.1 TWh (about 32.8 Mtce) in 2012 [22], accounting for only 2% of the total electricity generation and only 1% of the national energy production. Generating more hydroelectricity is a challenge as China can hardly construct another Three Gorges hydroelectric power station. Economic and grid access issues are the main restraining factors for the utilization of wind power and solar energy is much more expensive than other energy sources in China. China has a large potential for producing biomass energy in rural areas, but this form of energy is difficult to collect and utilize. Nuclear energy production is limited by safety concerns, the availability of production materials, and the long construction times for new plants. Thus, energy production from renewable and nuclear energy sources will not significantly increase in the near future due to the distribution of these resources, economic considerations, environmental impacts, technology levels, and production safety limitations [23]. China must therefore evaluate whether enough energy can be imported to supplement domestic energy production and satisfy demand. China is importing increasing amounts of oil, coal, and natural gas as shown in Fig. 9. In 2011, total energy imports were 623 Mtce, 17.2% of the total energy supply. Crude oil imports totaled 363 Mtce, equivalent to 57.7% of the total crude oil supply [24]. The amount of energy that can be imported relies heavily on policies of energy exporting countries, transportation safety, and the global energy market. However, to ensure national security, China should not depend on imports to meet its energy requirements, but should supply at least 80% of the energy it needs [25]. The Chinese government has an energy self-sufficiency target of 90% [26].
Fig. 9. Chinese energy imports.
312
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
Table 1 Obtainable energy resources in China (Mtce).
Coal Natural gas Oil Hydropower Nuclear power Wind power Solar electricity Solar heating Biomass
Domestic production
Imports
2100 283–321 300–329 327 163–186 62–93 4.6–9.2 30 100–145
– 129 428 – – – – – –
Thus, the Chinese energy supply is restricted by many factors. The CAE has shown that total energy supply will range from 3.93 to 4.09 billion tce in 2020 [23]. Obtainable energy resources are listed by source in Table 1. Although China may produce more energy as technology advances, scarcity of energy reserves will always affect China’s sustainable development. Energy supply can be increased if extraction of fossil fuels is encouraged and the government does not promote sustainable development and consider the economic and environmental costs of energy production. Renewable and nuclear energy cannot replace fossil fuels as China’s main energy source in the next 20–30 years. Accordingly, energy use cannot exceed 4 billion tce per year, which means that China must control energy use by limiting energy supply. 3.1.2. CO2 emission reduction requirements Combustion of fossil fuels is the main source of CO2 emissions from human activities. Fig. 10 shows that global CO2 emissions from fossil fuel combustion exceeded 30 billion tons in 2010, or 4.4 tons per capita [14]. China’s CO2 emissions totaled 7.3 billion tons, corresponding to 24% of the total. China’s per capita CO2 emissions were 5.4 tons, a little above the world average. Total CO2 emissions in China were nine times those in 1971. This significant increase in CO2 emissions has drawn the world’s attention, with immense pressure on China’s increase in energy use. The Intergovernmental Panel on Climate Change (IPCC) recommended that Earth’s average temperature increase should be no more than 2 ◦ C relative to pre-industrial levels [27,28]. To achieve this target, China’s CO2 emissions must be reduced. The suggested recommendations are: (1) The peak of total Chinese CO2 emissions should not exceed 40 billion tons per year by about 2020. About 35 billion tons of all CO2 emissions will come from the combustion of fossil fuels [29]. If the world’s population reaches 7.66 billion as in the UN’s forecast [30], CO2 emissions per capita should be limited to no 8
China
CO2 emissions (Gt)
7
Fig. 11. Energy use by sector in 2010.
more than 4.5 tons. With coal as the main fossil fuel in China, the annual amount of coal burned for combustion should be less than 1.9 tce per capita and total fossil fuel use would be 2.7 billion tce for a population of 1.44 billion [3]. If more oil and gas is used than the global average, the total fossil fuel use could reach 3.1 billion tce. (2) Total CO2 emissions in 2050 should be 48–72% compared to those of 2000. Thus, unless the structure of energy use is changed, such as a switch to more renewable and nuclear energy sources, the total energy use must be reduced. In China, coal accounts for 68% of the total primary energy use. As coal emits more CO2 than other fossil fuels, China will have more difficulties reducing CO2 emissions than other countries, so overall energy use must be reduced. During the meeting of President Xi Jinping and President Obama in November 2014, China formally announced for the first time that it expects to reach its peak of carbon emissions in 2030, and committed to increasing the proportion of non-fossil energy use to 20% in the same year, reflecting China’s determination to respond to climate change. Government polices encouraging the development of renewable and nuclear energy sources could raise this proportion to 30% of the total energy used [23]. China’s total primary energy supply could then reach 3.7–4.4 billion tce. According to NDRC’s plan that national energy use should not exceed 4.8 billion tce in 2020, China will try to control each kind of energy end-use to achieve this target. 3.1.3. Summary Considering available energy supplies and the need to limit CO2 emissions, the ceiling of total primary energy use must be limited to less than 4.8 billion tce and fossil fuel usage should be strictly limited. Renewable and nuclear energy sources cannot replace fossil fuels to a significant degree due to technical, economic, and resource limitations. Thus, each kind of energy end-use must be restricted, including building energy use. 3.2. Building energy use limits
6 5 4 3 2 1 0 1970
1975
USA
1980 Japan
1985
1990
EU27
1995 Russia
2000
2005
China
Fig. 10. CO2 emissions of several world regions.
2010 India
Building energy use accounts for about 35% of the world’s total energy use [5]. Fig. 11 shows the percentage of energy use for different countries and regions. China’s building energy use accounts for only about 20% of the national energy use, which is much lower than the world’s average with a larger portion of energy used for China’s industrial sector [1,6,11,31,32]. As total energy use must be limited, the energy use for each sector has to be restricted as well. In 2011, the total primary energy use was 3.48 billion tce, with an energy use for the industrial and agricultural sector of 2.51 billion tce. Energy use for the transportation sector was 0.29 billion tce, while energy use for the building
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
313
Fig. 12. Energy use trends by sector in China.
Energy use per capita (toe/cap.)
sector was 0.69 billion tce (excluding biomass energy). Energy use for each sector has been increasing yearly as shown in Fig. 12 [1,33]. Industry is the main driver of China’s economic development and the manufacturing sector will be the key economic driver of China’s development for the foreseeable future. With this demand for industrial development, industrial energy use is bound to increase. China has indicated it will cut CO2 emissions by 40–45% below 2005 levels by 2020 [34]. Thus, even as industry’s share of the GDP increases, the total energy used by the industry should be limited to less than 3 billion tce, or, preferably, kept at the current level. In 2009, transportation energy use per capita was only 0.21 tce, less than half of the world’s average as shown in Fig. 13 [31–33,35], and much less than in developed countries such as the USA, the EU, and Japan. If China’s transportation energy use per capita reaches the world’s average, the total amount will be 700 Mtce, more than triple that of current levels. Green travel must be encouraged to save energy. China may be able to keep total transportation energy use to less than 500 Mtce through effective policies and technological advances, which means that the energy use per capita will be slightly below the global average. Today, total building energy use is less than 0.7 billion tce. However, increasing urbanization, including the expansion of building floor space and improved living standards, will significantly increase building energy use. When considering the ceiling for total energy use and the development needs for industry, farming, building, and transportation, the total energy use for the building sector should remain below 1.1 billion tce (excluding biomass energy) as shown in Fig. 14. This limit on the total national building energy use must be distributed among the different sectors in the CBEM classification.
Fig. 14. Future energy use for each sector.
4. Discussion – building energy use allotments 4.1. Current building energy use characteristics in China Building energy use increases are being driven by factors such as building floor space, population, urbanization rate, ownership of equipment, and usage patterns. It seems that most of these factors will increase building energy use as the development of society and economy progresses. This trend is also very clear from the total building energy use patterns of the past ten years [36]. However, it seems that this trend does not attract enough attention. The Chinese population will peak at 1.47 billion around 2030, with an urbanization rate of 70% [37]. If the energy use intensity in each subsector maintains the current trends and building floor space increases to 60 billion m2 (with residential building floor space reaching 30 m2 per capita in urban areas and 40 m2 per capita in rural areas, and commercial and public building floor spaces increasing by 50%), the building energy use would reach 1189 Mtce by 2020 and 1938 Mtce by 2030 as shown in Fig. 15. This means that, if building energy use is not carefully controlled, it will represent half of the total national energy use in 2012. At this rate, building energy use would exceed the proposed limit. Therefore, it is necessary to limit the building energy use intensity and keep it below 1.1 billion tce, which is the main target for future building energy conservation in China. Since the characteristics and drivers for each subsector differ, trends for each subsector’s energy use will differ. Meeting the total energy use target will require allotments for each subsector, with specific energy conservation strategies and policies for each subsector.
2.5
2.0
1.5
1.0
0.5
0.0 USA
Europe
Japan
Brazil
China
India
Fig. 13. Transportation energy use per capita in 2009.
World
Fig. 15. Future building energy use based on current trends.
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
4.2.2. Commercial and public buildings (C&P excl. SHNUC) Building floor space and energy intensity of C&P excl. SHNUC will also continue to increase due to the demand for better working conditions and the use of centralized systems for space cooling, lighting, and water heating, which are inefficient and may cause over-usage [36]. Over the past 10 years, the energy intensity of C&P increased slightly for mainly two reasons. First, energy use demands of indoor environment control systems (including space heating and cooling, lighting, and ventilation) and office appliances have increased. Second, building shapes and sizes are changing. More and more large-scale buildings are being constructed whose energy use intensity is much higher than that of more traditional buildings.
Energy use (Mtce)
4.2.1. Space heating in Northern Urban China (SHNUC) The SHNUC energy use is a function of building floor space with space heating and energy intensity. A building’s heating demand, heat losses during distribution, and the energy efficiency of the heat source are the main factors for calculating the SHUNC energy intensity [16]. In the past ten years (from 2001 to 2011), the energy use intensity of SHUNC was reduced by about 6 kgce/m2 by promoting building energy efficiency standards and improving the energy efficiency of the heat source. A building energy efficiency standard named “building energy conservation design standard for space heating of residential buildings” (JGJ 26-1986) was first announced in 1986, which tried to reduce heat demand by 30% compared to previous buildings [38]. This standard was revised in 1995 and the target was increased to 50% reduction in heat demand [39]. After the year 2000, several standards for different types of buildings and climate zones were implemented and the target was increased to 65% in the 2010 residential building energy efficiency design standard in the severe cold and cold climate zone (JGJ 26-2010) [40]. New buildings should be designed according to these building energy efficiency standards and the government has provided funds for improving the energy performance of existing buildings through envelope insulation. Large-scale combined heat and power (CHP) systems were promoted for district space heating and a significant number of coal boilers were abandoned for low energy efficiency. The SHUNC floor space will increase as total building floor space increases in the northern urban areas. However, there is still a large potential for energy conservation by decreasing energy intensity such as retrofitting building envelope insulation in existing buildings built before 2000. Overheating and network consume more than 30% of the total supplied space heating. The main reasons for such large heating losses are that it is usually difficult for district heating systems to flexibly adjust heat output according to the climate and that heating mechanisms, which are laid out according to floor space instead of the required amount of heating, are ineffective for energy conservation. In addition, many low-efficiency boilers are still used for space heating. Considering the current status of building envelope performance and boilers’ energy efficiency, energy intensity can be reduced from 16 kgce/m2 to 10 kgce/m2 by improving building insulation, pricing schemes, and heating efficiencies, and by utilizing industrial waste heat. As shown in Fig. 16, the total SHNUC energy use is to not exceed 150 Mtce for a space heating floor space of 15 billion m2 .
20
150
15 100 10 50
5
0
0 2001
2003
2005
2007
Energy use
2009
2011
Future
Intensity
Fig. 16. SHNUC energy use and intensity.
Large buildings need more energy for controlling the indoor environment and typically use centralized systems, which usually use more energy, as they are more difficult to adjust to different demands. Building design and system operations are important factors affecting the energy intensity. Energy conservation in C&P buildings can be improved by designing systems to: (1) use natural lighting and natural ventilation as much as possible, (2) encourage “part time, part space” operations, and (3) promote decentralized systems for cooling, heating, ventilation, and lighting, except for special cases (such as heating and cooling systems for sports arenas and hospital and hotel water heating systems). With regard to energy use in commercial and public buildings, the energy conservation target in C&P buildings is to keep the average energy intensity to about 20 kgce/m2 and to limit the total energy use to no more than 240 Mtce for a floor space of 12 billion m2 , as shown in Fig. 17. 4.2.3. Urban residential buildings (UR excl. SHNUC) Energy is used in residential buildings for space cooling, space heating, water heating, lighting, cooking, and appliances. The growth of the urban population is a main reason for increased energy use. The energy intensity will continue to increase as the demand for better living standards increases [1]. Many people will move to urban areas as the Chinese economy develops. The energy demands for cooling, domestic appliances, and hot water will increase because current usage levels are still quite low. Thus, there will be greatly increased demand as living standards improve. Lighting energy use can be decreased by the use of more energy efficient light bulbs, but cooking energy use
Energy use (Mtce)
Building energy use is allotted based on the current characteristics of each type of building, including energy intensity, population, building floor space, and trends in energy demands. Targets and key measures are:
25
200
Energy intensity (kgce/m2)
4.2. Energy use allotments for each subsector
300
24
250
20
200
16
150
12
100
8
50
4 0
0 2001
2003
2005
2007
Energy use
2009
2011
Future
Intensity
Fig. 17. C&P excl. SHNUC energy use and intensity.
Energy intensity (kgce/m2)
314
350
300
300
250
250
200
200 150 150 100
100
50
50 0 2003
2005
2007
2009
Energy use
Population (million)
Floor space (billion m2 ) SHNUC Current Future C&P excl. SHNUC Current Future UR excl. SHNUC Current Future RR excl. SHNUC Current Future
0 2001
315
Table 2 Energy use targets for each type of building.
Energy intensity (kgce/capita)
Energy use (Mtce)
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
2011
Energy use (Mtce)
10.2 15
/ /
166 150
8 12
/ /
171 240
/ /
690 1000
153 290
/ /
660 470
197 150
Intensity
Fig. 18. UR excl. SHNUC energy use and intensity.
will not change by much. It is thought that some appliances such as clothes dryers, dishwashers, and washers that operate with hot water will cause a significant increase in energy use when widely used by Chinese families [9]. For these reasons, the total energy use of urban residential buildings will see a significant increase. By encouraging green lifestyles and promoting suitable energy efficient technologies, the urban residential energy intensity should be limited to no more than 290 kgce per capita. Accordingly, the total energy use for urban residential buildings should be no more than 290 Mtce for an urban population of 1 billion, as shown in Fig. 18. 4.2.4. Rural residential buildings (RR) Both commercial and biomass energy sources are used in rural areas. However, commercial energy use is increasing although the population in rural areas is decreasing because more and more people prefer to use commercial energy resources instead of biomass for cooking, space heating, and water heating [41]. The total population in rural areas will continue to decrease as urbanization increases, but the energy intensity will increase with the demand for improved living standards. Energy use in rural residential areas will be the biggest uncertainty factor for China’s future building energy use due to two quite different possible scenarios. One is that rural residential buildings will be built in the same way as urban residential buildings and that commercial energy will replace biomass energy, causing a significant increase in the demand for electricity, liquefied petroleum gas (LPG), and coal.
Another is that people will construct buildings in rural areas using natural materials and widely use biomass energy, which would reduce the demand of commercial energy. Therefore, to protect the environment and conserve natural resources, “ecological villages” in the south and “no coal villages” in the north should be encouraged in rural areas [41]. Biomass energy is abundant in rural areas and can be used for cooking, space heating, and water heating. Thus, the commercial energy intensity will not increase significantly and a limit of 320 kgce per capita will be sufficient for RR according to current projections. As the population decreases, total building energy use in rural areas should not exceed 150 Mtce, as shown in Fig. 19.
4.3. Summary This analysis has shown that building energy use in China can be kept below a desired ceiling. Current energy use and future allotments for each type of building are listed in Table 2. Building energy use is projected to reach about 830 Mtce for a population of roughly 1.47 billion people and a building floor space of about 60.8 billion m2 . This result has been analyzed by experts from the Chinese Academy of Engineering, the NDRC Energy Research Institute and others. To achieve this target, building floor space must be limited and more innovative technologies are needed to accommodate the occupants’ behavior. If building floor space exceeds 80 billion m2 , building energy use will exceed 1.1 billion tce, even if the energy intensity does not increase.
300
Energy use (Mtce)
200 250 150
200 150
100
100 50 50 0
0 2001
2003
2005
2007
Energy use
2009
2011
Intensity
Fig. 19. RR energy use and intensity.
Future
Energy intensity (kgce/capita)
350
250
316
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
5. Conclusions Although technical progress has greatly improved energy system efficiencies, building energy use in China is increasing with improving living standards. However, total energy use is limited by energy supply and the need to reduce carbon emissions. Therefore, energy use for industry, buildings, and transportation must not be allowed to increase at the same rate as economic and social developments. This study projects a ceiling for China’s building energy use. The data analysis indicates that: (1) Total energy use in China cannot exceed 4 billion tce due to limitations regarding obtainable energy and the need to limit carbon emissions, (2) consideration of each sector’s energy use resulted in a projected ceiling for building energy use of 1.1 billion tce, and (3) targets listed in Table 2 for building energy use subsectors are based on current conditions and projected trends of energy demand. Above all, more research in building energy use control with regard to both technological and policy aspects are needed to enable sustainable environmental, social, and economic development in China. Acknowledgements This study is supported by “the 12th Five-Year” National Key Technology R&D Program of China (Grant No. 2012BAJ12B01) and the Housing and Urban Systems strategy to address climate change research (Grant No. 2010DFB73870-01). References [1] THUBERC, 2013 Annual Report on China Building Energy Efficiency, China Building Industry Press, Beijing, China, 2013. [2] NBS, China Statistical Database, 2013 http://data.stats.gov.cn/workspace/ index?m=hgnd [3] Project Team of National Development and Reform Energy Research Institute, China’s Low Carbon Development Pathways by 2050, Science Press, Beijing, China, 2009. [4] NBS, China Statistical Yearbook 2012, China Statistics Press, Beijing, China, 2012. [5] IEA, World Energy Outlook 2012, IEA, Paris, 2012. [6] EIA, Annual Energy Outlook 2013, 2013. [7] C. Peng, Quantitative description and simulation of human behavior in residential buildings, Build. Simul. 5 (2) (2012) 85–94. [8] M. Grinshpon, A Comparison of Residential Energy Consumption Between the United States and China (master thesis), Tsinghua University, 2011. [9] S. Hu, Research on Residential Building Energy Consumption of China’s Urban Area and Comparison with Developed Countries (Master thesis), Tsinghua University, 2013.
[10] D. Zhou, China’s Sustainable Energy Scenarios in 2020, Environmental Science Press, China, 2003. [11] EIA, International Energy Outlook 2012, 2012. [12] NDRC, The state council on the issuance of energy development “Twelfth Five Year Plan”, 2013 http://www.gov.cn/zwgk/201301/23/content 2318554.html (accessed 23.01.13). [13] NDRC, National Climate Change Plan (2014–2020 years), 2014, http://www. sdpc.gov.cn/zcfb/zcfbtz/201411/t20141104 642612.html [14] IEA, CO2 Emissions from Fuel Combustion 2012, IEA, Paris, 2012. [15] X. Yang, Study of China’s Building Energy Efficiency Based on Energy Data, PhD thesis of Tsinghua University, 2009. [16] THUBERC, 2011 Annual Report on China Building Energy Efficiency, China Building Industry Press, Beijing, China, 2011. [17] S. Liao, et al., Estimation of Grid Based spatial Distribution of wind energy resource in China, GEO-inform. Sci. 10 (5) (2008) 551–556. [18] K. Li, F. He, Analysis on Mainland China’s solar energy distribution and potential to utilize solar energy as an alternative energy source, Progr. Geogr. 29 (9) (2010) 1049–1054. [19] MLR, 2013, http://www.mlr.gov.cn/zygk/#, http://www.mlr.gov.cn/xwdt/ jrxw/201303/t20130328 1196769.htm [20] BP, BP Statistical Review of World Energy 2013, 2013. [21] Takungpao, 2012, http://www.takungpao.com/paper/content/2012-08/25/ content 989707.htm (accessed 27.11.13). [22] CTGC, Annual Report of China Three Gorges Corporation, 2012, http://www. ctgpc.com.cn/gsgk/gsnb.php [23] Project Team of China Medium and Long Term Development Strategic Research, China Energy Medium and Long Term (2030, 2050) Development Strategic Research (Comprehensive Volume), Science Press, China, 2011. [24] CESY, China Energy Statistical Yearbook 2012, China Statistics Press, Beijing, China, 2012. [25] L. Zhang, Energy security and resources internationalization of China, Resour. Sci. 24 (1) (2002) 1–4. [26] SCIO, China’s Energy Policy (2012), 2012, http://www.gov.cn/jrzg/2012-0/24/ content 2250377.htm (accessed 27.11.13). [27] IPCC WGIII, Fourth Assessment Report, 2007. [28] M. Meinshausen, et al., Greenhouse-gas emission targets for limiting global warming to 2 ◦ C, Nature 458 (7242) (2009) 1158–1162. [29] C.L. Quéré, et al., The global carbon budget 1959–2011, Earth Syst. Sci. Data Discuss. 5 (2) (2012) 1107–1157. [30] DOE, World Population Prospects, The 2010 Revision, DOE, USA, 2011. [31] EDMC, Handbook of Energy & Economic Statistics in Japan, The Energy Conservation Center, Japan, 2011. [32] Eurostat European Commission, Europe in Figures Eurostat Yearbook, Eurostat European Commission, Belgium, 2011. [33] NBS, China Statistical Yearbook 2011, China Statistics Press, Beijing, China, 2011. [34] UNFCCC, 2009, http://greenleapforward.com/2009/11/26/china-to-adoptbinding-goal-to-reduce-co2-emissions-per-unit-gdp-by-40-to-45-of-2005levels-by-2020/ [35] DOE, World Population Prospects, DOE, USA, 2012. [36] THUBERC, 2014 Annual Report on China Building Energy Efficiency, China Building Industry Press, Beijing, China, 2014. [37] NDRC, China Low Carbon Development Road in 2050, Science Press, Beijing, China, 2009. [38] MOC, Energy Conservation Design Standard for New Heating Residential Buildings, JGJ26-1986, China Building Industry Press, Beijing, China, 1986. [39] MOC, Energy Conservation Design Standard for New Heating Residential Buildings, JGJ26-95, China Building Industry Press, Beijing, China, 1995. [40] MOHURD, Design Standard for Energy Efficiency of Residential Buildings in Serve Cold and Cold Zones, JGJ 26-2010, China Building Industry Press, Beijing, China, 2010. [41] THUBERC, 2012 Annual Report on China Building Energy Efficiency, China Building Industry Press, Beijing, China, 2012.
Contents lists available at ScienceDirect
Energy and Buildings journal homepage: www.elsevier.com/locate/enbuild
Building energy use in China: Ceiling and scenario Chen Peng, Da Yan ∗ , Siyue Guo, Shan Hu, Yi Jiang Building Energy Research Center, Tsinghua University, Beijing, China
a r t i c l e
i n f o
Article history: Received 10 March 2015 Received in revised form 28 May 2015 Accepted 29 May 2015 Available online 1 June 2015 Keywords: Building energy use Energy supply CO2 emissions Ceiling
a b s t r a c t With increasing levels of urbanization and a growing economy, total building energy use in China is rapidly increasing. However, energy use must be controlled due to limited energy supply and the goal of lowering carbon emissions. This study tried to define a reasonable limit for total energy use in China, and, more specifically, a target for building energy use. Domestic energy production, energy imports, and the need to reduce CO2 emissions and fossil fuel combustion were considered when analyzing the available energy for China. The current status and future trends of energy use by industry, building, and transportation sectors were analyzed to determine how much energy the building sector can use considering economic growth and improving living conditions. Within the framework of “Ecological civilization,” this study suggests that annual building energy use in China has to be limited to no more than 1 billion tce. © 2015 Elsevier B.V. All rights reserved.
1. Introduction Building energy use in China has been increasing rapidly in recent years. In 2011, the total building energy use was 687 Mtce (million tons of coal equivalent) [1], 1.5 times that of 2000. The total residential electricity use almost tripled from 145 TWh (terawatthours) to 562 TWh [2]. These large increases of building energy use were caused by the rapid increase of building floor space and energy use intensity for all building types. Constructed building floor space was about 3.16 billion m2 in 2011, up from only 1.6 billion m2 in 2000. In addition, more people are moving from rural regions of the country to urban areas. The urbanization rate is expected to increase from 51.3% to 70% by 2030, which means that China’s urban population will increase to more than 300 million [3]. As additional buildings will be built to accommodate these people, energy use will also increase as the demand grows. The ownership rate of domestic appliances and air conditioning units is also rapidly increasing which is reflected in the rapid growth of the energy use [4]. However, building energy use in China continues to remain far below that of developed countries, whether per capita or per square meter. In per capita terms, China’s building energy use was only 1/8 that of the USA and 1/4 that of Japan and the EUG4 countries (United
∗ Corresponding author. Tel.: +86 15910715460. E-mail addresses: [email protected] (C. Peng), [email protected] (D. Yan), [email protected] (S. Guo), [email protected] (S. Hu), [email protected] (Y. Jiang). http://dx.doi.org/10.1016/j.enbuild.2015.05.049 0378-7788/© 2015 Elsevier B.V. All rights reserved.
Kingdom, France, Germany and Italy) in 2012 (Fig. 1) [1,5,6]. With regard to factors that affect building energy use, different usage modes and lifestyles are the main reasons for the differences in energy use intensities [7–9]. Building energy use will increase as the economy develops and people’s living standards improve, which means that usage modes and lifestyles will change. These changes may include an increase of appliance ownership and usage, as well as improvements to the indoor environment. For example, with an ownership rate for air conditioners of 126.8% for urban households, people will be able to install about three air conditioners per household (one air conditioner per room) [2]. The indoor temperature is considered too low during the winter in the Yangtze River basin and too high during the summer in the southern areas of the country. If the per capita energy use would reach the level of the EUG4, China’s building energy use alone would be 2.9 billion tce (tons of coal equivalent), close to China’s total energy use in 2010. If the energy use per capita reached the level of the USA, the building energy use will be more than twice China’s total energy use in 2010. Several institutes are investigating China’s building energy use, including the International Energy Agency (IEA), U.S. Energy Information Administration (EIA), Lawrence Berkeley National Laboratory (LBNL), Energy Research Institute National Development and Reform Commission of China (NDRC), and the Building Energy Research Center of Tsinghua University (BERC), all of which have published reports about building energy use in China. These reports predict that China’s building energy use will increase in the future as shown in Fig. 2, even though opinions about the current situation differ [10,11]. All reports used a bottom-up approach for their
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
Energy intensity per floor space (kgce/(m 2·a))
308
100 90
Russia, 213
80 70
Korea, 59
USA, 1438
60 Canada, 80
Japan, 163
50 40
India, 283
EU4,396
30 20
China, 648
10
Brazil, 49
0 0
1
2 3 4 Energy intensity per capita (tce/(ca·a))
5
6
2. Method
Fig. 1. Building energy use intensities in 2010.
scenario analyses by analyzing the energy demand for each type of end use. However, the obtainability of energy resources in China was not considered. The IEA analysis, which included an effort to reduce CO2 emission (450 Scenario), found that China’s building energy use should not exceed 835 Mtce by 2030. A “total energy use control” plan was announced in former President Hu Jintao’s report at the 18th Party Congress as an important part of the “ecological civilization”, which is one of the five overarching plans for the development of China. It states that there should be a ceiling for energy use and that total energy use should be strongly controlled. With this guiding ideology, the Chinese government published the Energy Development “Twelfth Five Year Plan” at the beginning of 2013, which announced that China would limit total energy use to no more than 4 billion tce by 2015 [12]. This target was set by considering energy security, resources, environment, technologies, and economic factors. The plan also announced that imported oil should contribute no more than 61% to the total oil demand. The total primary energy use will be limited to no more than 4.8 billion tce by 2020 in the “National Climate Change Plan for 2014–2020” which was released in November 2014 by the NDRC [13]. However, if energy supply cannot meet the energy demand, the country’s entire economy will be in danger. China cannot depend on imported energy to support its development, as China is a very large country whose total energy use represents a large part of the global energy use. Thus, China is determined to
Building energy use (Mtce)
1400 1200 1000
IEA, 450 scenario
800 600 400 200
608.2949 995.3917 1271.889
0 2010
2020 EIA
IEA
2030 ERI
achieve its energy conservation targets by controlling total energy use. In general, China’s building energy use is significantly lower than of developed countries. However, driven by social and economic development, the country’s building energy use is growing fast, which has received much attention from academia and government. If the increase in building energy use continues too rapidly, the environment and the economy will be adversely affected. Most existing research has focused on energy use forecasts and carbon emissions reductions, but there have been few studies of China’s energy supply. Different features of China’s building energy use also have to be carefully considered since developments of China’s building sector are quite different from those in other countries. This study presents a method to predict the ceiling of Chinese building energy use. The model describes each type of building energy use based on BERC’s CBEM (China Building Energy Model) and current building energy use characteristics.
LBNL
Fig. 2. Predicted future building energy use in China. Note: 1. Biomass energy was not included; 2. Different energy policies were considered in the IEA scenarios and different energy prices were considered in the EIA scenario.
As mentioned in the introduction, there have been various scenario analyses of China’s building energy use. However, there has been little consideration of energy use constraints such as limited energy reserves, which may present significant limitations. At the same time, China’s building energy use will differ from that of developed countries due to its dual urban–rural structure and large amount of building floor space with district heating systems in northern urban areas [1]. This study uses a constraint model for building energy use and the national building energy use model (CBEM) developed by THUBERC to predict how building energy use can be limited to a predetermined ceiling. 2.1. Energy use constraint analysis model Energy use is limited by the total energy supply and requirements of CO2 emission reductions. Combined energy resources include fossil fuels, renewable energy resources, and nuclear energy, with all three categories being limited by reserves, technical limitations, and environmental and economic factors. Total energy supply from both domestic and foreign sources cannot increase indefinitely. In addition, fossil fuel usage must be restricted to limit climate change [14]. For these reasons, China’s energy use has to be limited to a predetermined ceiling both for total energy use and energy use of each sector, including industry, buildings, and transportation. Each of these sectors will see growing energy demand in the future. The energy use constraint analysis model is described in Fig. 3. Total energy use is limited by energy supply and CO2 emissions. Domestic and imported energy supplies and energy types must be considered when analyzing energy supply limitations. The current fossil fuel energy supply structure and CO2 emissions are references for CO2 emission limitations. On the other hand, economic and social development will require increasing industrial, building, and transportation energy supply as China develops. As the manufacturing industry is China’s economic pillar, it is difficult to reduce industrial energy use. Increasing travel and car ownership rates are the main drivers for transportation energy use. The drivers for building energy use include population (total population and urbanization rate), economic growth, building floor space, and the culture of energy consumption. Building energy use must be carefully assigned if there is a ceiling on total energy use. Otherwise, any economic and social development will be severely affected. Finding the ceiling for building energy use requires a large amount of data on energy supply and CO2 emissions. China’s
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
309
Fig. 3. Maximum energy use model.
current status and the situation of some of the developed countries were considered when analyzing the demand of industrial and transportation energy use.
2.2. CBEM methodology Analysis of building energy demand depends on current characteristics, including total energy use as well as energy type and purpose. However, the National Bureau of Statistics does not have enough data to clearly understand the building energy use. Thus, an energy use model or energy data analysis tools are needed. As mentioned in the introduction, there have been several studies of Chinese building energy use. Tsinghua University developed the China Building Energy Model in 2009 [15]. This model is being updated to describe the national building energy use characteristics. This model uses a bottom-up method that considers each kind of end use including space heating and cooling, lighting, water heating, appliances, and cooking as shown in Fig. 4. Since climates vary significantly from north to south, the country is divided into five climate zones when considering energy use for heating and cooling. The CBEM uses a different building energy use classifications than most other studies. In most energy use studies, the building energy use was divided into a residential sector and a service sector (or commercial sector). However, building energy use characteristics in China are different from those in other countries.
Building Energy Use
First, there are large district space heating systems in northern urban China. Space heating regulations put in place since the 1950s have created centrally controlled district heating systems, which supply space heating throughout the entire heating season. It was found that over 80% of the building floor area in northern urban regions is supported by district space heating [16]. Few other countries have such large-scale district space heating systems, which often supply tens of thousands or even millions of square meters with heat. Operating time and supplied heat of district space heating systems are controlled by heating companies, which differ with regard to the way they use the decentralized space heating systems. If energy conservation is the goal, more attention has to be paid to the energy efficiency of the heat supply source and to heat loss during the distribution process in addition to the performance of the building envelope. It is apparent that the energy use mode and approach to energy conservation with regard to district space heating are quite different from other kinds of end use. In addition, the energy use for space heating in the northern urban areas is much higher than in the Yangtze River basin, which also experiences cold winter temperatures. However, these energy use differences are not just caused by differences in climate, but mainly by different space heating systems and usage patterns. Second, as China is a developing country, there are significant differences in residential building energy use between urban and rural areas due to differences in lifestyle, income, fuel types, building types, and so on. Farmers build their own houses, while
Population
Floor Space
Urban
Space Heating in North Urban China
Heating
Severe Cold
Commercial and Public buildings (excl. SHNUC)
Cooling
Cold
Hot Water
Hot Summer and Cold Winter
Rural
Urban Residential buil dings (excl. SHNUC)
Appliances / Other
Hot Summer and Warm Winter
Households
Rural Residential buildings
Cooking
Lighting
Temperate
Fig. 4. Structure of the CBEM. Note: The dashed line indicates that energy use for heating is only considered for the Hot Summer and Cold Winter Climate zone.
310
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
Energy Intensity
Corrceon
Floor area and household
Energy balance from NBS annual data
Energy calculaon
No
Verificaon Yes China building Energy use Fig. 5. Flow chart of CBEM.
houses in urban areas mainly built by real estate developers. In addition, most houses in rural areas are single-family units, while most houses in urban areas are multi-family units, including many high-rise residential buildings. Accordingly, building energy conservation policies have to address these differences in energy use between urban and rural areas. Therefore, building energy use in China should be divided into four subsectors to analyze energy use trends and future requirements for each sector. The four subsectors are Space Heating in Northern Urban China (abbr. SHNUC), Commercial and Public buildings (excl. SHNUC) (abbr. C&P excl. SHNUC), Urban Residential buildings (excl. SHNUC) (abbr. UR excl. SHNUC) and Rural Residential buildings (abbr. RR). Model inputs include energy intensity, population, number of households, and floor area. The energy intensity for each kind of building was derived from a large-scale survey and case study that has been conducted since 2007. For SHUNC, heating systems of more than 10 cities were analyzed as part of this study. For C&P excl. SHNUC, we had survey data and measurements conducted in different climate zones for hundreds of buildings. For UR excl. SHNUC, we had access to about 20,000 questionnaires about household energy use as well as about 150 case studies, covering all climate zones. For RR, we had access to about 10,000 questionnaires from across the country. Population and household data were taken from the Statistical Yearbook of the Republic of China. The floor area data are based on the statistical yearbook, related reports, and our own survey. Using these data, the total energy use of the building sector in China can be calculated. Then, the National Bureau of Statistics’ energy balance data were used as the constraint on the total building energy use calculated by CBEM, to verify the model [16]. Fig. 5 shows a flow chart of the model. As shown in Fig. 6, each subsector’s energy use accounted for about a quarter of the total building energy use in China in 2011
Fig. 7. National energy use by fuel type.
[1]. Fuel types and end uses for each subsector were also calculated for data analysis. This study combines investigations from 2008 to 2013 to predict the ceiling of energy use and a reasonable range for future energy use by the building sector. Energy conservation targets are then recommended based on the current characteristics for each subsector. 3. Results – energy use ceiling for China The total energy use in China is rapidly increasing due to social and economic development. Fig. 7 illustrates the increasing trend for total energy use from 1978 to 2011. It can be seen that the national energy use increased rapidly after 2000. From 2001 to 2011, energy use increased from 1.5 billion tce to 3.48 billion tce, an increase of 8.8% per year. Fossil fuels accounted for about 92% of the total energy use in 2011 with coal as the main energy source, accounting for 68.4%. Hydroelectric, wind, and nuclear energy accounted for only 8%. Fossil fuels such as coal are widely used in China because of abundant reserves and low extraction costs. Coal is the main fuel for electricity generation and is widely used for manufacturing (e.g., for steel and cement production) and district heating. Oil is mainly used for transportation, with natural gas also used for electricity generation, space heating, and cooking. China has paid much attention to renewable energy development with a number of hydropower plants. Solar collectors are also widely used for water heating. However, little electricity is generated from photovoltaic or wind power systems due to the non-continuous availability of these resources (wind and solar) and non-uniform distribution [17,18]. The amount and structure of energy use are restricted by the energy supply characteristics. In addition, CO2 emissions must be considered when using fossil fuels. This section analyzes the ceiling for energy use based on these two considerations. 3.1. The ceiling for total energy use
Fig. 6. Building energy use in China in 2011.
3.1.1. Upper limits of energy supply The total energy supply includes domestic energy production and imported energy. In 2011, the total domestic energy production was 3.18 billion tce with imports of 0.62 billion tce, or 16% of the total energy supply [4]. Domestic energy production included fossil fuels, renewable energy sources, and nuclear energy. China has an abundant supply of coal, which accounted for 77.8% of the total energy production in 2011, with oil and gas accounting for 9.1% and 4.3%, respectively. Energy supplied from hydro, nuclear, and wind power accounted for 8.8% of the domestic energy production.
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
311
Fig. 8. Fossil fuels reserves in 2011.
Energy production is restricted by energy reserves, production capabilities, safety, and economics. Although China has large reserves of fossil fuels, the per capita quantity is lower than in other countries, due to its large population (about 1.35 billion people in 2012). As shown in Fig. 8, the per capita coal, oil, and gas reserves are only 2/3, 1/14, and 1/9 of the world average, respectively [19,20]. China has abundant coal reserves, but production is limited by safety considerations. The death rate per million tons of coal produced is about 10 times that of the developed countries [21]. In addition, the coal producing areas are mainly in the northern and western parts of China, which results in high coal transportation costs. At the same time, coal combustion is causing serious environmental pollution. Therefore, a further increase in the use of coal is not tenable and the Chinese government has determined to limit the usage of coal to no more than 4.2 billion tons per year [13]. Chinese oil and natural gas reserves are very limited. Natural gas occurs mainly in western part of China and the Chinese Academy of Engineering (CAE) noted that natural gas production could not exceed 250 billion m3 per year, with a current production of 100 billion m3 per year. In addition, oil production cannot be easily increased without the discovery of new oil fields. In general, fossil fuel production is limited by reserves, the cost of production and transportation, production capabilities, and safety, capping the supply of fossil fuel at around 2.75 billion tce. Renewable energy sources include hydro, wind, solar, and biomass. The hydro, wind, and biomass energy source are mainly located in western China, while the energy demand is greatest in eastern China. Thus, transportation is expensive, which restricts the use of these energy sources. New hydropower plants must consider relocation of people living in the reservoir area and
environmental disruption, in addition to the limited availability of hydropower resources. The Three Gorges hydroelectric power station is China’s largest hydropower station and generated 98.1 TWh (about 32.8 Mtce) in 2012 [22], accounting for only 2% of the total electricity generation and only 1% of the national energy production. Generating more hydroelectricity is a challenge as China can hardly construct another Three Gorges hydroelectric power station. Economic and grid access issues are the main restraining factors for the utilization of wind power and solar energy is much more expensive than other energy sources in China. China has a large potential for producing biomass energy in rural areas, but this form of energy is difficult to collect and utilize. Nuclear energy production is limited by safety concerns, the availability of production materials, and the long construction times for new plants. Thus, energy production from renewable and nuclear energy sources will not significantly increase in the near future due to the distribution of these resources, economic considerations, environmental impacts, technology levels, and production safety limitations [23]. China must therefore evaluate whether enough energy can be imported to supplement domestic energy production and satisfy demand. China is importing increasing amounts of oil, coal, and natural gas as shown in Fig. 9. In 2011, total energy imports were 623 Mtce, 17.2% of the total energy supply. Crude oil imports totaled 363 Mtce, equivalent to 57.7% of the total crude oil supply [24]. The amount of energy that can be imported relies heavily on policies of energy exporting countries, transportation safety, and the global energy market. However, to ensure national security, China should not depend on imports to meet its energy requirements, but should supply at least 80% of the energy it needs [25]. The Chinese government has an energy self-sufficiency target of 90% [26].
Fig. 9. Chinese energy imports.
312
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
Table 1 Obtainable energy resources in China (Mtce).
Coal Natural gas Oil Hydropower Nuclear power Wind power Solar electricity Solar heating Biomass
Domestic production
Imports
2100 283–321 300–329 327 163–186 62–93 4.6–9.2 30 100–145
– 129 428 – – – – – –
Thus, the Chinese energy supply is restricted by many factors. The CAE has shown that total energy supply will range from 3.93 to 4.09 billion tce in 2020 [23]. Obtainable energy resources are listed by source in Table 1. Although China may produce more energy as technology advances, scarcity of energy reserves will always affect China’s sustainable development. Energy supply can be increased if extraction of fossil fuels is encouraged and the government does not promote sustainable development and consider the economic and environmental costs of energy production. Renewable and nuclear energy cannot replace fossil fuels as China’s main energy source in the next 20–30 years. Accordingly, energy use cannot exceed 4 billion tce per year, which means that China must control energy use by limiting energy supply. 3.1.2. CO2 emission reduction requirements Combustion of fossil fuels is the main source of CO2 emissions from human activities. Fig. 10 shows that global CO2 emissions from fossil fuel combustion exceeded 30 billion tons in 2010, or 4.4 tons per capita [14]. China’s CO2 emissions totaled 7.3 billion tons, corresponding to 24% of the total. China’s per capita CO2 emissions were 5.4 tons, a little above the world average. Total CO2 emissions in China were nine times those in 1971. This significant increase in CO2 emissions has drawn the world’s attention, with immense pressure on China’s increase in energy use. The Intergovernmental Panel on Climate Change (IPCC) recommended that Earth’s average temperature increase should be no more than 2 ◦ C relative to pre-industrial levels [27,28]. To achieve this target, China’s CO2 emissions must be reduced. The suggested recommendations are: (1) The peak of total Chinese CO2 emissions should not exceed 40 billion tons per year by about 2020. About 35 billion tons of all CO2 emissions will come from the combustion of fossil fuels [29]. If the world’s population reaches 7.66 billion as in the UN’s forecast [30], CO2 emissions per capita should be limited to no 8
China
CO2 emissions (Gt)
7
Fig. 11. Energy use by sector in 2010.
more than 4.5 tons. With coal as the main fossil fuel in China, the annual amount of coal burned for combustion should be less than 1.9 tce per capita and total fossil fuel use would be 2.7 billion tce for a population of 1.44 billion [3]. If more oil and gas is used than the global average, the total fossil fuel use could reach 3.1 billion tce. (2) Total CO2 emissions in 2050 should be 48–72% compared to those of 2000. Thus, unless the structure of energy use is changed, such as a switch to more renewable and nuclear energy sources, the total energy use must be reduced. In China, coal accounts for 68% of the total primary energy use. As coal emits more CO2 than other fossil fuels, China will have more difficulties reducing CO2 emissions than other countries, so overall energy use must be reduced. During the meeting of President Xi Jinping and President Obama in November 2014, China formally announced for the first time that it expects to reach its peak of carbon emissions in 2030, and committed to increasing the proportion of non-fossil energy use to 20% in the same year, reflecting China’s determination to respond to climate change. Government polices encouraging the development of renewable and nuclear energy sources could raise this proportion to 30% of the total energy used [23]. China’s total primary energy supply could then reach 3.7–4.4 billion tce. According to NDRC’s plan that national energy use should not exceed 4.8 billion tce in 2020, China will try to control each kind of energy end-use to achieve this target. 3.1.3. Summary Considering available energy supplies and the need to limit CO2 emissions, the ceiling of total primary energy use must be limited to less than 4.8 billion tce and fossil fuel usage should be strictly limited. Renewable and nuclear energy sources cannot replace fossil fuels to a significant degree due to technical, economic, and resource limitations. Thus, each kind of energy end-use must be restricted, including building energy use. 3.2. Building energy use limits
6 5 4 3 2 1 0 1970
1975
USA
1980 Japan
1985
1990
EU27
1995 Russia
2000
2005
China
Fig. 10. CO2 emissions of several world regions.
2010 India
Building energy use accounts for about 35% of the world’s total energy use [5]. Fig. 11 shows the percentage of energy use for different countries and regions. China’s building energy use accounts for only about 20% of the national energy use, which is much lower than the world’s average with a larger portion of energy used for China’s industrial sector [1,6,11,31,32]. As total energy use must be limited, the energy use for each sector has to be restricted as well. In 2011, the total primary energy use was 3.48 billion tce, with an energy use for the industrial and agricultural sector of 2.51 billion tce. Energy use for the transportation sector was 0.29 billion tce, while energy use for the building
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
313
Fig. 12. Energy use trends by sector in China.
Energy use per capita (toe/cap.)
sector was 0.69 billion tce (excluding biomass energy). Energy use for each sector has been increasing yearly as shown in Fig. 12 [1,33]. Industry is the main driver of China’s economic development and the manufacturing sector will be the key economic driver of China’s development for the foreseeable future. With this demand for industrial development, industrial energy use is bound to increase. China has indicated it will cut CO2 emissions by 40–45% below 2005 levels by 2020 [34]. Thus, even as industry’s share of the GDP increases, the total energy used by the industry should be limited to less than 3 billion tce, or, preferably, kept at the current level. In 2009, transportation energy use per capita was only 0.21 tce, less than half of the world’s average as shown in Fig. 13 [31–33,35], and much less than in developed countries such as the USA, the EU, and Japan. If China’s transportation energy use per capita reaches the world’s average, the total amount will be 700 Mtce, more than triple that of current levels. Green travel must be encouraged to save energy. China may be able to keep total transportation energy use to less than 500 Mtce through effective policies and technological advances, which means that the energy use per capita will be slightly below the global average. Today, total building energy use is less than 0.7 billion tce. However, increasing urbanization, including the expansion of building floor space and improved living standards, will significantly increase building energy use. When considering the ceiling for total energy use and the development needs for industry, farming, building, and transportation, the total energy use for the building sector should remain below 1.1 billion tce (excluding biomass energy) as shown in Fig. 14. This limit on the total national building energy use must be distributed among the different sectors in the CBEM classification.
Fig. 14. Future energy use for each sector.
4. Discussion – building energy use allotments 4.1. Current building energy use characteristics in China Building energy use increases are being driven by factors such as building floor space, population, urbanization rate, ownership of equipment, and usage patterns. It seems that most of these factors will increase building energy use as the development of society and economy progresses. This trend is also very clear from the total building energy use patterns of the past ten years [36]. However, it seems that this trend does not attract enough attention. The Chinese population will peak at 1.47 billion around 2030, with an urbanization rate of 70% [37]. If the energy use intensity in each subsector maintains the current trends and building floor space increases to 60 billion m2 (with residential building floor space reaching 30 m2 per capita in urban areas and 40 m2 per capita in rural areas, and commercial and public building floor spaces increasing by 50%), the building energy use would reach 1189 Mtce by 2020 and 1938 Mtce by 2030 as shown in Fig. 15. This means that, if building energy use is not carefully controlled, it will represent half of the total national energy use in 2012. At this rate, building energy use would exceed the proposed limit. Therefore, it is necessary to limit the building energy use intensity and keep it below 1.1 billion tce, which is the main target for future building energy conservation in China. Since the characteristics and drivers for each subsector differ, trends for each subsector’s energy use will differ. Meeting the total energy use target will require allotments for each subsector, with specific energy conservation strategies and policies for each subsector.
2.5
2.0
1.5
1.0
0.5
0.0 USA
Europe
Japan
Brazil
China
India
Fig. 13. Transportation energy use per capita in 2009.
World
Fig. 15. Future building energy use based on current trends.
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
4.2.2. Commercial and public buildings (C&P excl. SHNUC) Building floor space and energy intensity of C&P excl. SHNUC will also continue to increase due to the demand for better working conditions and the use of centralized systems for space cooling, lighting, and water heating, which are inefficient and may cause over-usage [36]. Over the past 10 years, the energy intensity of C&P increased slightly for mainly two reasons. First, energy use demands of indoor environment control systems (including space heating and cooling, lighting, and ventilation) and office appliances have increased. Second, building shapes and sizes are changing. More and more large-scale buildings are being constructed whose energy use intensity is much higher than that of more traditional buildings.
Energy use (Mtce)
4.2.1. Space heating in Northern Urban China (SHNUC) The SHNUC energy use is a function of building floor space with space heating and energy intensity. A building’s heating demand, heat losses during distribution, and the energy efficiency of the heat source are the main factors for calculating the SHUNC energy intensity [16]. In the past ten years (from 2001 to 2011), the energy use intensity of SHUNC was reduced by about 6 kgce/m2 by promoting building energy efficiency standards and improving the energy efficiency of the heat source. A building energy efficiency standard named “building energy conservation design standard for space heating of residential buildings” (JGJ 26-1986) was first announced in 1986, which tried to reduce heat demand by 30% compared to previous buildings [38]. This standard was revised in 1995 and the target was increased to 50% reduction in heat demand [39]. After the year 2000, several standards for different types of buildings and climate zones were implemented and the target was increased to 65% in the 2010 residential building energy efficiency design standard in the severe cold and cold climate zone (JGJ 26-2010) [40]. New buildings should be designed according to these building energy efficiency standards and the government has provided funds for improving the energy performance of existing buildings through envelope insulation. Large-scale combined heat and power (CHP) systems were promoted for district space heating and a significant number of coal boilers were abandoned for low energy efficiency. The SHUNC floor space will increase as total building floor space increases in the northern urban areas. However, there is still a large potential for energy conservation by decreasing energy intensity such as retrofitting building envelope insulation in existing buildings built before 2000. Overheating and network consume more than 30% of the total supplied space heating. The main reasons for such large heating losses are that it is usually difficult for district heating systems to flexibly adjust heat output according to the climate and that heating mechanisms, which are laid out according to floor space instead of the required amount of heating, are ineffective for energy conservation. In addition, many low-efficiency boilers are still used for space heating. Considering the current status of building envelope performance and boilers’ energy efficiency, energy intensity can be reduced from 16 kgce/m2 to 10 kgce/m2 by improving building insulation, pricing schemes, and heating efficiencies, and by utilizing industrial waste heat. As shown in Fig. 16, the total SHNUC energy use is to not exceed 150 Mtce for a space heating floor space of 15 billion m2 .
20
150
15 100 10 50
5
0
0 2001
2003
2005
2007
Energy use
2009
2011
Future
Intensity
Fig. 16. SHNUC energy use and intensity.
Large buildings need more energy for controlling the indoor environment and typically use centralized systems, which usually use more energy, as they are more difficult to adjust to different demands. Building design and system operations are important factors affecting the energy intensity. Energy conservation in C&P buildings can be improved by designing systems to: (1) use natural lighting and natural ventilation as much as possible, (2) encourage “part time, part space” operations, and (3) promote decentralized systems for cooling, heating, ventilation, and lighting, except for special cases (such as heating and cooling systems for sports arenas and hospital and hotel water heating systems). With regard to energy use in commercial and public buildings, the energy conservation target in C&P buildings is to keep the average energy intensity to about 20 kgce/m2 and to limit the total energy use to no more than 240 Mtce for a floor space of 12 billion m2 , as shown in Fig. 17. 4.2.3. Urban residential buildings (UR excl. SHNUC) Energy is used in residential buildings for space cooling, space heating, water heating, lighting, cooking, and appliances. The growth of the urban population is a main reason for increased energy use. The energy intensity will continue to increase as the demand for better living standards increases [1]. Many people will move to urban areas as the Chinese economy develops. The energy demands for cooling, domestic appliances, and hot water will increase because current usage levels are still quite low. Thus, there will be greatly increased demand as living standards improve. Lighting energy use can be decreased by the use of more energy efficient light bulbs, but cooking energy use
Energy use (Mtce)
Building energy use is allotted based on the current characteristics of each type of building, including energy intensity, population, building floor space, and trends in energy demands. Targets and key measures are:
25
200
Energy intensity (kgce/m2)
4.2. Energy use allotments for each subsector
300
24
250
20
200
16
150
12
100
8
50
4 0
0 2001
2003
2005
2007
Energy use
2009
2011
Future
Intensity
Fig. 17. C&P excl. SHNUC energy use and intensity.
Energy intensity (kgce/m2)
314
350
300
300
250
250
200
200 150 150 100
100
50
50 0 2003
2005
2007
2009
Energy use
Population (million)
Floor space (billion m2 ) SHNUC Current Future C&P excl. SHNUC Current Future UR excl. SHNUC Current Future RR excl. SHNUC Current Future
0 2001
315
Table 2 Energy use targets for each type of building.
Energy intensity (kgce/capita)
Energy use (Mtce)
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
2011
Energy use (Mtce)
10.2 15
/ /
166 150
8 12
/ /
171 240
/ /
690 1000
153 290
/ /
660 470
197 150
Intensity
Fig. 18. UR excl. SHNUC energy use and intensity.
will not change by much. It is thought that some appliances such as clothes dryers, dishwashers, and washers that operate with hot water will cause a significant increase in energy use when widely used by Chinese families [9]. For these reasons, the total energy use of urban residential buildings will see a significant increase. By encouraging green lifestyles and promoting suitable energy efficient technologies, the urban residential energy intensity should be limited to no more than 290 kgce per capita. Accordingly, the total energy use for urban residential buildings should be no more than 290 Mtce for an urban population of 1 billion, as shown in Fig. 18. 4.2.4. Rural residential buildings (RR) Both commercial and biomass energy sources are used in rural areas. However, commercial energy use is increasing although the population in rural areas is decreasing because more and more people prefer to use commercial energy resources instead of biomass for cooking, space heating, and water heating [41]. The total population in rural areas will continue to decrease as urbanization increases, but the energy intensity will increase with the demand for improved living standards. Energy use in rural residential areas will be the biggest uncertainty factor for China’s future building energy use due to two quite different possible scenarios. One is that rural residential buildings will be built in the same way as urban residential buildings and that commercial energy will replace biomass energy, causing a significant increase in the demand for electricity, liquefied petroleum gas (LPG), and coal.
Another is that people will construct buildings in rural areas using natural materials and widely use biomass energy, which would reduce the demand of commercial energy. Therefore, to protect the environment and conserve natural resources, “ecological villages” in the south and “no coal villages” in the north should be encouraged in rural areas [41]. Biomass energy is abundant in rural areas and can be used for cooking, space heating, and water heating. Thus, the commercial energy intensity will not increase significantly and a limit of 320 kgce per capita will be sufficient for RR according to current projections. As the population decreases, total building energy use in rural areas should not exceed 150 Mtce, as shown in Fig. 19.
4.3. Summary This analysis has shown that building energy use in China can be kept below a desired ceiling. Current energy use and future allotments for each type of building are listed in Table 2. Building energy use is projected to reach about 830 Mtce for a population of roughly 1.47 billion people and a building floor space of about 60.8 billion m2 . This result has been analyzed by experts from the Chinese Academy of Engineering, the NDRC Energy Research Institute and others. To achieve this target, building floor space must be limited and more innovative technologies are needed to accommodate the occupants’ behavior. If building floor space exceeds 80 billion m2 , building energy use will exceed 1.1 billion tce, even if the energy intensity does not increase.
300
Energy use (Mtce)
200 250 150
200 150
100
100 50 50 0
0 2001
2003
2005
2007
Energy use
2009
2011
Intensity
Fig. 19. RR energy use and intensity.
Future
Energy intensity (kgce/capita)
350
250
316
C. Peng et al. / Energy and Buildings 102 (2015) 307–316
5. Conclusions Although technical progress has greatly improved energy system efficiencies, building energy use in China is increasing with improving living standards. However, total energy use is limited by energy supply and the need to reduce carbon emissions. Therefore, energy use for industry, buildings, and transportation must not be allowed to increase at the same rate as economic and social developments. This study projects a ceiling for China’s building energy use. The data analysis indicates that: (1) Total energy use in China cannot exceed 4 billion tce due to limitations regarding obtainable energy and the need to limit carbon emissions, (2) consideration of each sector’s energy use resulted in a projected ceiling for building energy use of 1.1 billion tce, and (3) targets listed in Table 2 for building energy use subsectors are based on current conditions and projected trends of energy demand. Above all, more research in building energy use control with regard to both technological and policy aspects are needed to enable sustainable environmental, social, and economic development in China. Acknowledgements This study is supported by “the 12th Five-Year” National Key Technology R&D Program of China (Grant No. 2012BAJ12B01) and the Housing and Urban Systems strategy to address climate change research (Grant No. 2010DFB73870-01). References [1] THUBERC, 2013 Annual Report on China Building Energy Efficiency, China Building Industry Press, Beijing, China, 2013. [2] NBS, China Statistical Database, 2013 http://data.stats.gov.cn/workspace/ index?m=hgnd [3] Project Team of National Development and Reform Energy Research Institute, China’s Low Carbon Development Pathways by 2050, Science Press, Beijing, China, 2009. [4] NBS, China Statistical Yearbook 2012, China Statistics Press, Beijing, China, 2012. [5] IEA, World Energy Outlook 2012, IEA, Paris, 2012. [6] EIA, Annual Energy Outlook 2013, 2013. [7] C. Peng, Quantitative description and simulation of human behavior in residential buildings, Build. Simul. 5 (2) (2012) 85–94. [8] M. Grinshpon, A Comparison of Residential Energy Consumption Between the United States and China (master thesis), Tsinghua University, 2011. [9] S. Hu, Research on Residential Building Energy Consumption of China’s Urban Area and Comparison with Developed Countries (Master thesis), Tsinghua University, 2013.
[10] D. Zhou, China’s Sustainable Energy Scenarios in 2020, Environmental Science Press, China, 2003. [11] EIA, International Energy Outlook 2012, 2012. [12] NDRC, The state council on the issuance of energy development “Twelfth Five Year Plan”, 2013 http://www.gov.cn/zwgk/201301/23/content 2318554.html (accessed 23.01.13). [13] NDRC, National Climate Change Plan (2014–2020 years), 2014, http://www. sdpc.gov.cn/zcfb/zcfbtz/201411/t20141104 642612.html [14] IEA, CO2 Emissions from Fuel Combustion 2012, IEA, Paris, 2012. [15] X. Yang, Study of China’s Building Energy Efficiency Based on Energy Data, PhD thesis of Tsinghua University, 2009. [16] THUBERC, 2011 Annual Report on China Building Energy Efficiency, China Building Industry Press, Beijing, China, 2011. [17] S. Liao, et al., Estimation of Grid Based spatial Distribution of wind energy resource in China, GEO-inform. Sci. 10 (5) (2008) 551–556. [18] K. Li, F. He, Analysis on Mainland China’s solar energy distribution and potential to utilize solar energy as an alternative energy source, Progr. Geogr. 29 (9) (2010) 1049–1054. [19] MLR, 2013, http://www.mlr.gov.cn/zygk/#, http://www.mlr.gov.cn/xwdt/ jrxw/201303/t20130328 1196769.htm [20] BP, BP Statistical Review of World Energy 2013, 2013. [21] Takungpao, 2012, http://www.takungpao.com/paper/content/2012-08/25/ content 989707.htm (accessed 27.11.13). [22] CTGC, Annual Report of China Three Gorges Corporation, 2012, http://www. ctgpc.com.cn/gsgk/gsnb.php [23] Project Team of China Medium and Long Term Development Strategic Research, China Energy Medium and Long Term (2030, 2050) Development Strategic Research (Comprehensive Volume), Science Press, China, 2011. [24] CESY, China Energy Statistical Yearbook 2012, China Statistics Press, Beijing, China, 2012. [25] L. Zhang, Energy security and resources internationalization of China, Resour. Sci. 24 (1) (2002) 1–4. [26] SCIO, China’s Energy Policy (2012), 2012, http://www.gov.cn/jrzg/2012-0/24/ content 2250377.htm (accessed 27.11.13). [27] IPCC WGIII, Fourth Assessment Report, 2007. [28] M. Meinshausen, et al., Greenhouse-gas emission targets for limiting global warming to 2 ◦ C, Nature 458 (7242) (2009) 1158–1162. [29] C.L. Quéré, et al., The global carbon budget 1959–2011, Earth Syst. Sci. Data Discuss. 5 (2) (2012) 1107–1157. [30] DOE, World Population Prospects, The 2010 Revision, DOE, USA, 2011. [31] EDMC, Handbook of Energy & Economic Statistics in Japan, The Energy Conservation Center, Japan, 2011. [32] Eurostat European Commission, Europe in Figures Eurostat Yearbook, Eurostat European Commission, Belgium, 2011. [33] NBS, China Statistical Yearbook 2011, China Statistics Press, Beijing, China, 2011. [34] UNFCCC, 2009, http://greenleapforward.com/2009/11/26/china-to-adoptbinding-goal-to-reduce-co2-emissions-per-unit-gdp-by-40-to-45-of-2005levels-by-2020/ [35] DOE, World Population Prospects, DOE, USA, 2012. [36] THUBERC, 2014 Annual Report on China Building Energy Efficiency, China Building Industry Press, Beijing, China, 2014. [37] NDRC, China Low Carbon Development Road in 2050, Science Press, Beijing, China, 2009. [38] MOC, Energy Conservation Design Standard for New Heating Residential Buildings, JGJ26-1986, China Building Industry Press, Beijing, China, 1986. [39] MOC, Energy Conservation Design Standard for New Heating Residential Buildings, JGJ26-95, China Building Industry Press, Beijing, China, 1995. [40] MOHURD, Design Standard for Energy Efficiency of Residential Buildings in Serve Cold and Cold Zones, JGJ 26-2010, China Building Industry Press, Beijing, China, 2010. [41] THUBERC, 2012 Annual Report on China Building Energy Efficiency, China Building Industry Press, Beijing, China, 2012.