China's energy consumption in the building sector: A life cycle approach

China's energy consumption in the building sector: A life cycle approach

Accepted Manuscript Title: China’s energy consumption in the building sector: A life cycle approach Author: Yan Zhang Chen-Qi He Bao-Jun Tang Yi-Ming ...

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Accepted Manuscript Title: China’s energy consumption in the building sector: A life cycle approach Author: Yan Zhang Chen-Qi He Bao-Jun Tang Yi-Ming Wei PII: DOI: Reference:

S0378-7788(15)00203-0 http://dx.doi.org/doi:10.1016/j.enbuild.2015.03.011 ENB 5744

To appear in:

ENB

Received date: Revised date: Accepted date:

10-11-2014 30-1-2015 2-3-2015

Please cite this article as: Y. Zhang, C.-Q. He, B.-J. Tang, Y.-M. Wei, China’s energy consumption in the building sector: A life cycle approach, Energy and Buildings (2015), http://dx.doi.org/10.1016/j.enbuild.2015.03.011 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

China’s energy consumption in the building sector: A life cycle approach Yan Zhang a, b, Chen-Qi He a, b, Bao-Jun Tang a, b, Yi-Ming Wei a, b, * a. Center for Energy and Environmental Policy Research, Beijing Institute of Technology, Beijing 100081, China

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b. School of Management and Economics, Beijing Institute of Technology, Beijing 100081, China

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Abstract: Currently, there is no clear and unified understanding about the status quo of China’s energy consumption in the building sector. In addition, a considerable underestimation of energy associated

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with buildings has impeded the effective implementation of measures to improve building energy

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efficiency of China. Thus, in this paper, we seek to identify the building sector’s energy consumption of China by establishing an estimation model of building energy consumption from a life cycle

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perspective. On the basis of macro-level statistical data and relevant literature, we analyze the activities in each phase and calculate associated energy consumptions throughout buildings’ whole life cycle in

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China from 2001 to 2013. The results show that China’s energy consumption associated with buildings

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has reached 1.66 billion tons coal equivalent in 2013, with a stable growth rate of 7% annually since

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2001. Buildings’ life-cycle energy has approximately accounted for 43% of China’s total energy consumption for recent three years (2011-2013). What’s more, energy consumption in buildings’ operation phase has been salient, accounting for over 20% of China’s total energy consumption. More focus should be drawn on energy efficiency in building material production phase and energy consumed in China’s rural residential buildings as both have been significantly neglected. Keywords: Building energy consumption; Building energy efficiency; Life cycle approach; China

1. Introduction

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Corresponding author. Tel./ Fax: 86-10-68918009. E-mail addresses: [email protected], [email protected] (Y.M. Wei) 1

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Buildings are responsible for more than 40% of global energy use and one-third of global greenhouse gas emissions [1]. China, the second largest energy consumer after the U.S., is also the second largest building energy user across the world, ranking first in residential energy consumption

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and third in commercial energy consumption [2]. Energy efficiency in buildings has long been regarded as a key component of energy security to reduce the energy dependence and energy bills for end-users

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[3].

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Building energy consumption cannot be overlooked in guaranteeing China’s energy security and addressing problems caused by climate change. On one hand, China’s primary policy of promoting

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urbanization has led to its growth in building floor area, which reached approximately 55 billion square

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meters in 2010 [4]. Accordingly, energy consumption associated with buildings in China inevitably has displayed an upward trend along with the rapid urbanization process. On the other hand, currently,

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there is no clear and consistent understanding in academia of energy consumption in China’s building sector, as well as its ratio to the national energy consumption despite a myriad of related studies. Tu [5]

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calculated that China’s building energy consumption was 350 Mtce in 2000, accounting for 27.5% of

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the total energy consumption, and thus predicting the building energy consumption of China will increase to 1089 Mtce in 2020. Tsinghua University Buildings Energy Efficiency Research Center [6] concluded in its report that the total commercial energy consumption ascribed to buildings was up to 563 Mtce, accordingly accounting for 23.1%. Wang [7] estimated that China’s building energy consumption in 2005 reached 552 Mtce and its ratio in total energy consumption was 34.0%. By integrated analysis, Long [8] judged the ratio of building energy consumption in China was approximately 20%, and hence giving the quantity of building energy consumption of 330 Mtce in 2003. The Ministry of Housing and Urban-Rural Development of China (MOHURD) [9] pointed out in 2

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2012 that building energy consumption accounted for 27.5% of the total energy consumption, without explicitly revealing the total quantity of building energy consumption. International Energy Agency (IEA) [2] indicated that China's building sector consumed 31% of its total primary energy in 2007.

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Given the vague and inconsistent understanding of energy consumed in buildings, it is imperative to thoroughly analyze energy-related-activities in the building sector to ascertain the characteristics and

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developing trend of China’s building energy consumption. However, disparities in studies of that area

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have exacerbated the confusion of understanding, which can boil down to two aspects as follows: 1) Comprehension of building energy consumption and its ratio.

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Generally, there are two different interpretations of building energy consumption. The first refers

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to energy used in buildings during their operational phase, which is in consistent with international common usage. Most studies on building energy efficiency currently focused on operating energy,

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including energy used for heating, ventilation, air conditioning, hot water supply, lighting, cooking, office facilities and other electrical appliances. The other one is defined as the total energy used in

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buildings’ life cycle, i.e. not only including energy used in their operational phase, but also that

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consumed in building material production, building construction, building demolition, etc. Bekker [10] first applied the life cycle approach in building energy analysis and demonstrated it

was appropriate to deal with the problem of limited resources in terms of buildings by means of a life-cycle approach. Thereafter, Adalberth [11] elaborated the method of calculating the energy use during the life cycle of a building. Suzuki and Oka [12] estimated the life cycle energy consumption of office buildings in Japan and discussed its impact on the environment. Life-cycle energy analysis of buildings was conducted with case study [13, 14] to accurately evaluate energy and environment performance of buildings. Malmqvist et al. [15] discussed the reasons of limited application of life 3

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cycle assessment in the building sector and proposed a simplified methodology facilitating the assessment process. With respect to the ratio of energy consumption associated with buildings to the national

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consumption, researchers also have divergent understandings. Some treated the national total energy consumption as the ensemble, while others employed the final energy consumption (also called as

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end-use energy consumption). Apparently, the former value of the ratio would be larger than the latter.

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For the present, the choice of end-use energy consumption is predominant due to the accessibility of energy statistical data as well as better decision-making of energy policy.

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2) Approaches to determining building energy consumption.

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In general, the basic idea of estimating building energy consumption is to establish a practicable model to identify the building energy performance in a certain country or region with the help of

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accessible data. The modeling methods in existed studies on that topic can fall into two categories: the

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Insert Fig.1 here

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top-down and the down-top approaches, as shown in Fig. 1.

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The top-down approach primarily explores the interaction between the energy sector and macro

economy, without distinguishing energy consumption due to individual end-uses. The variables generally employed in the models include macroeconomic indicators (e.g. gross domestic product, employment rates, and price indexes), climate conditions, the rates of construction or demolition, etc. Based on the characteristics of variables used, top-down models can broadly be grouped into two categories: technological and econometric models. The building energy consumption of a certain 4

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country or region in a given year can be estimated by means of top-down models with aggregated economic data and historical information of energy consumption. Swan and Ugursal [16] had elaborated these models in their review article. The significant deficiency of top-down approach is its

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incapacity to identify the focus areas of improving building energy efficiency, due to over-relying on historical information and the lack of reflecting discontinuous advances in technology.

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The bottom-up approach puts emphasis on disaggregated components, obtaining national or

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regional building energy consumption by extrapolating from the energy consumption of sample buildings. This approach is based on plentiful and detailed survey data at a micro level [17] and can be

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classified into statistical methods and engineering methods. Statistical methods, primarily

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encompassing regression analysis [18, 19], conditional demand analysis [20, 21] and neural network analysis [22, 23], largely depend on the integrity of statistical information. Engineering methods, based

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on buildings’ engineering characteristics, basically embrace the utilization of distributions of appliances, archetypes of buildings [24-27] and samples of buildings [28, 29].

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This paper aims to identify the building energy consumption of China during 2001-2013 from a

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perspective of life cycle analysis. With the help of appropriate model tailored to calculate China’s building energy consumption on a macroscopic view, we can have a clear and integrated image of energy consumption related to buildings in China, and discern the characteristics of China’s building energy consumption as well as its developing trends. Furthermore, customized policy suggestions are given and thus benefiting improvement and promotion of building energy efficiency in China. The following section (Section 2) introduces the approach of life cycle assessment and establishes a proper model estimating building energy consumption in China. Section 3 employs the given model to determine the energy consumption situations of buildings in China during 2001-2013, on the basis of 5

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which characteristics of building energy consumption of China are further analyzed in Section 4. Finally, Section 5 presents central conclusions and policy implications obtained from in-depth analysis.

2. Methodology

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2.1 Building life cycle assessment

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Life cycle is the whole process of a product (or a service) from its design, raw material extraction

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through materials processing, manufacture, distribution, utilization, maintenance, and disposal or recycling, i.e. a process from cradle to grave just as indicated in some articles [18-20]. Life cycle

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assessment (LCA) is an approach broadly applied to evaluate the environmental impacts of buildings throughout their life span [30]. LCA studies generally consist of four phases: goal and scope definition,

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life cycle inventory (LCI), impact assessment and interpretation of results [31].LCA in the construction

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industry is less developed today than in other industries, but appears to be developing quickly [32]. For recent years, many LCAs have been carried out in the building sector, by urban designers, property

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developers, architects, engineers, and consultants [33].LCA studies in the building sector mainly

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focused on the quantification of energy and materials used and wastes released into the environment throughout the life cycle [34]. Bribián conducted an LCA study comparing the most commonly used building materials with some eco-materials using three different impact categories [30], and further presented the state-of-the-art regarding the application of life cycle assessment (LCA) in the building sector [35]. Sartori performed a literature survey on buildings’ life cycle energy use with a total of 60 cases from nine countries and put more emphasis on operating energy throughout the life cycle of buildings [36]. In addition, a large number of researchers applied LCA to case studies of buildings’ energy system and environmental impacts [37-40].

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2.2 Building energy consumption model in a life-cycle viewpoint From the perspective of life cycle, the energy consumption of a building encompasses energy used in related activities throughout the building’s life cycle, including building materials production,

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building construction, building operation and building demolition. Fig. 2 shows the system boundaries

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of building life cycle energy analysis [23].

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Insert Fig.2 here

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Specifically, the energy used in a building’s life cycle substantially involves that of manufacturing

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stage, operation stage and demolishing stage. The manufacturing stage contains excavating of raw

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materials, manufacturing of building materials, transportation of related material and equipment, as well as construction of new buildings and renovation of existed buildings. The energy consumption

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components associated with this stage are cement, iron and steel, plastics, materials transportation, etc.

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Energy consumption in the operation stage ensures the functional operation of a building such as heating, ventilation, air conditioning, lighting and so on. The demolishing stage not only includes energy use for building demolition, materials transportation and waste disposal, but also energy conservation due to recycling of building material. National building energy consumption in this paper refers to the aggregated energy used in all life-cycle stages of buildings in China. With the combination of building life cycle boundaries and China’s statistical system, the estimation model of national building energy consumption can be expressed as:

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where

refers to national total building energy consumption over the life cycle;

energy consumed in the process of various building materials production;

represents

refers to energy

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consumption of site construction, including erection of new buildings and renovation of exited indicates the energy related to the operation stage;

buildings, as well as destruction of buildings;

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denotes energy savings from building materials recycling.

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2.3 Data and framework

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China’s total energy consumption ascribed to buildings through the whole life cycle can be determined by means of the established model and available data. The data employed in this section are

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derived from China Energy Statistical Yearbooks and China Statistical Yearbooks concerned, which are

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accessible on the website of National Bureau of Statistics of China (http://www.stats.gov.cn/). The

**************** Insert Fig.3 here

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estimation framework in this paper is shown in Fig. 3.

3. Results

3.1 Building materials production energy Building materials, involving over 2000 kinds of products, generally fall into two categories: metal materials, including steel, aluminum, copper, etc., and non-metal materials, such as cement, plate glass, architectural ceramics, stone, lime, plastics and new building materials. In terms of industries,

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metal materials are mainly distributed in ferrous metals industry and non-ferrous metals industry, and non-metal materials are related to building materials industry as well as the industry of rubber and plastics products. Considering the accessibility and applicability of data information, energy

represents energy consumed in the production of all kinds of building materials;

to energy for producing material ;

refers to the proportion of material

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used for buildings to its

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where

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consumption for building materials production can be calculated by the following formula:

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total output. Steel, aluminum and copper are selected as the representations of metal materials to simplify the process. Energy consumption for cement production, accounting for 70% of non-metal

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material production energy, is an excellent indicator to estimate the value of energy consumption for

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non-metal building materials industry. Fig. 4 presents the energy consumption of materials production and the floor space of buildings under construction in China for the period of 2001-2013. Obviously,

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the upward trend of energy consumption in building materials production has been highly consistent

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with the escalation of floor space of buildings under construction, which is partly in association with the rapid urbanization of China. However, in general, there was a distinct decline in energy use of building materials production per unit area, mostly due to the fall of energy intensities of related building materials as a result of technology and process improvements, just as shown in Fig. 5. The exceptional increase of building materials production energy per unit area in 2006 could be explained by the growing proportion of materials used for buildings., such as steel (from 41% in 2005 to 50% in 2006), aluminum (from 30% in 2005 to 35% in 2006) and copper (from 3% in 2005 to 4% in 2006).

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****************

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3.2 Construction energy

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In light of the fact that the erection of new buildings, renovation of exited buildings and destruction of buildings are closely connected with construction enterprises activities, it is appropriate

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to employ the energy consumption of construction industry to signify the construction energy. The

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energy consumption situation of construction industry in China during 2001-2013 is shown in Table 1.

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3.3 Operation energy

Given the differences of climate in the North and South, building energy consumption distinction

of urban and rural areas, and user behavior contrast of public and residential buildings, China’s building operation energy consumption (BOEC) can be divided into four categories: BOEC for heating in northern cities, BOEC of public buildings (heating excluded), BOEC of urban residential buildings (heating excluded) and BOEC of rural residential buildings. 3.3.1 Heating for northern cities Currently, about 70% of urban buildings in northern China have been covered in the areas of centralized heating during the winter season. The major heat source systems embrace coal-fired boiler 10

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and combined heat and power generation. Energy consumption of centralized heating in northern cities of China for the period of 2001-2013 has gradually increased along with the expansion of centralized heating areas, whereas energy consumption per unit heating area has basically kept a downward trend,

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indicating the improvement of energy efficiency in centralized heating, as shown in Fig. 6. Despite the fact that the energy consumption per unit heating area has generally decreased since 2001, the total

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energy for centralized heating in northern cities has risen largely due to the growth rate of centralized

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caused by centralized heating technology improvement.

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3.3.2 Public buildings

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heating areas overrunning the rate of decline in energy consumption intensity per unit heating area

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Energy consumption of public buildings includes energy used for offices, schools, hospitals,

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theaters, hotels, shopping malls, etc. excluding heating as well as transportation. China’s public buildings’ energy consumption has been largely underestimated for a long time in light of the results presented in Fig. 7. Energy used in public buildings has escalated since 2001 and reached 237 Mtce in 2013, companied with a growth rate of 5.76% in energy consumption per unit area. It is indispensable to highlight energy efficiency of public buildings as a critical ingredient to achieve nationally energy conservation and emission reduction.

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3.3.3 Urban residential buildings Energy used for urban residential buildings is connected to routine activities of urban residents in

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houses, and thus being calculated by residential energy consumption subtracting residential

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transportation energy use. The results are shown in Table 2.

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Insert Table 2 here

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3.3.4 Rural residential buildings

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In light of the widespread use of non-commercial energy in rural areas, this paper calculates the

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quantity of energy use in rural residential buildings by combining commercial and non-commercial energy consumption despite the exclusion of non-commercial energy in a number of related articles.

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Specifically, commercial energy refers to energy substantially consumed in the field of circulation as a

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commodity such as fossil fuels (coal, oil and natural gas), nuclear energy, and hydropower, while non-commercial energy is not included in market trade but locally collected and often unprocessed biomass-based fuels covering methane, straw and fuel wood. The proportion of non-commercial energy consumption to the total energy consumption in rural buildings is considerable in view of Fig. 8, although a decreasing trend has emerged in recent years. In 2013, the non-commercial energy consumption reached 77.03 Mtce, accounting for 31.5% of rural residential buildings energy consumption.

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3.3.5 Total operation energy The total operation energy consumption of buildings in China can be obtained by adding up the

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values of energy consumption in preceding four parts, as shown in Fig. 9. It has been relatively stable

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since 2006 after several years of mild growth at the average rate of 7.80% annually. The energy

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consumption per unit floor area during the operation stage has displayed a distinct downward trend for the period of 2007-2013, largely owing to the implementation of a series of policies aiming to improve

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building energy efficiency of China. In 2005, the Department of Science and Technology of MOHURD organized many relevant experts to conduct a wide variety of investigations and make multiple

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researches on building energy efficiency supervision and management. After that, especially between

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2006~2008, some effective and efficient policy measures, primarily building regulations and codes, were issued and implemented in light of intensive analyses and extensive investigations on other

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developed countries. For instance, the revised “Regulations on Energy Efficiency Management in Civil

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Building” was issued by MOHURD in November 2005 and then came into force since January 1, 2006. In addition, the first “Evaluation Standard for Green Building” was released in March 2006 and put into effect in June 2006, which promoted the expansion of green buildings throughout China. The supervision of building energy consumption, with particular attention on large-scale public buildings and energy efficiency retrofit for existing residential buildings in northern heating areas of China, has been strengthened since the establishment of “Civil Building Energy Consumption Statistics System” in 2007, the implementation of “Regulations on Energy Efficiency in Public Institutions” in 2008 and the release of “Implement Opinion on Promoting Energy Efficiency Management for Government Office Buildings and Large-scale Public Buildings” on October 23, 2007. 13

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**************** Insert Fig.9 here ****************

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3.4 Energy savings from recycling

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According to the study of Zhang and Fei (2010) [41], the recycling rate of construction waste in

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China is less than 5%, indicating a huge gap between China and some developed countries such as Germany (87%) and Japan (97%). Energy savings from recycling construction waste in the

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demolishing stage were not taken into consideration by most articles when estimating the life cycle

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energy of buildings due to disagreement on the attribution of energy benefit and difficulty in obtaining adequate and accurate data. However, the way incorporating energy savings from recycling into the life

represents saved energy;

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where

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recycling can be expressed as:

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cycle energy estimation of buildings would be more suitable on the whole [19]. Energy savings from

denotes production energy of building materials;

percentage representing the recycling rate of building materials, and

is a

here. The energy

savings of building materials recycling in China from 2001 to 2013 are presented in Table 3.

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3.5 Life cycle energy 14

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The national building energy consumption based on the life-cycle estimation model can be determined by aggregating the results of 3.1-3.4. China’s building energy consumption over the whole life cycle has experienced an uninterrupted growth (6.96% annually) from 738.64 Mtce in 2001 to

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1655.19 Mtce in 2013, as shown in Fig. 10.

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Insert Fig.10 here

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4. Discussion and analysis

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4.1 Total life cycle energy in the building sector

Fig. 11 presents the energy consumption of buildings in the whole life cycle in comparison with

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China’s total energy consumption and final energy consumption over the period of 2001-2013.

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According to China’s statistics system, total energy consumption refers to the total energy used by all sectors of national economy and households. It also could be termed as total primary energy

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consumption, such as in the statistics of Energy Information Administration. Basically, it is comprised of three parts, i.e. final energy consumption, energy losses during the process of energy conversion, and energy losses during the process of energy transmission, distribution and storage. Specifically, final energy consumption covers all energy used by the final end-use sectors: industry, building (including residential and commercial sub-sectors), and transport. Life cycle energy of buildings in a certain period embraces energy consumed by both new and existing buildings throughout the specified time. Obviously, China’ energy consumption in the building sector has displayed a highly consistent growth with these two indicators of macroscopic energy consumption. In fact, the average annual growth rate 15

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of building energy consumption has been 7% from 2001 through 2013, tantalizingly close to the value of 8% for the growth of both total energy consumption and final energy consumption. Furthermore, the proportion of building energy consumption to the total and final energy consumption can be seen in Fig.

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11 as well. The percentage of building energy consumption contributing to the total energy consumption has varied along with the percentage to the final energy consumption with strong

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consistency. Overall, the proportion of building energy consumption experienced a declining trend and

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hovered around 43% with respect to the national total energy consumption for recent years. It is significantly important to pay more attention to reduce the building sector’s energy demand and

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meanwhile to improve building energy efficiency for achieving the target of energy saving and

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emission reduction and ensuring energy security of China.

****************

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Insert Fig.11 here

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4.2 Structural composition of life cycle energy in buildings In terms of structural composition, the energy associated with building materials production,

building construction and building operation would add to the total life cycle energy, which could be partly offset by the energy benefit from recycling. As the energy benefit from recycling is puny (around 2% of the sum of the other three terms), it is appropriate to rule out the recycling stage for the purpose of facilitating the structural analysis. Fig. 12 depicts the composition of China’s energy consumption in the buildings throughout the life cycle from 2001 to 2013. On the one hand, building materials production energy and building operation 16

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energy predominate in the total life cycle energy. On the other hand, these two terms presented exactly opposite variation trends while the proportion of construction energy remained relatively stable throughout these years. Specifically, the proportion of building materials production energy gradually

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increased from 27.73% in 2001 to 49.20% in 2013, in contrast with the proportion of building operation energy dropping to 46.98% in 2013. The rapid urbanization of China in recent years has

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boosted the development of the construction industry, leading to the expansion of construction area as

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well as building materials’ use (as illustrated in Fig. 13). Therefore, the energy consumed in building materials production has inevitably mounted. What’s more, building operation energy is closely related

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to existing buildings of the period while building materials production and construction energy is

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mainly bound up with new buildings. Fig. 14 displays the relationship between building energy consumption and existing and new buildings. In terms of the average annual growth rate (AAGR),

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building operation energy (AAGR 4%) has been consistent with existing building area (AAGR 5%) throughout the period of 2001-2013. As the new building area of China has been booming since 2001

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with the AAGR of 12%, the growth of energy derived from building materials production and

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construction activity has outrun that of operation energy, which could partly explain the fall of the proportion of operation energy to life-cycle energy.

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Insert Fig.14 here ****************

4.3 Operation energy in buildings

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Operation energy in buildings has played a pivotal role in building life-cycle energy since most

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efforts were made to improve energy efficiency of buildings in the operating stage. Despite its decline

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in the proportion, building operation energy has reached 800 Mtce in 2003, accounting for 21% of China’s total energy consumption. With regard to the constitution of operation energy, the proportion of

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heating energy in northern cities has not shown drastic fluctuation, maintaining the rate of 13% since 2010. Furthermore, it will probably continue to climb in future as more areas have been planned into

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the national centralized heating system. Public buildings and urban residential buildings, as the hottest

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research objects, made almost equal contribution to the operation energy while a rising tendency of public buildings has been revealed in recent years, as shown in Fig. 15. Energy consumption from rural

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residential buildings accounted for over 50% of the operation energy during the period of 2001-2006

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and declined to 31% in 2013. It has been overlooked for a long time regardless of its significance to building operation energy. As more commercial energy has been used in rural areas, percentage of energy from rural residential buildings has experienced a downward trend, but it is still a potential field to effectively reduce energy consumption in the building sector of China in future.

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5. Conclusions and policy implications 18

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The rapid urbanization of China challenges its energy security and sustainable development along with the people’s increasing desire for indoor comfort. Building energy efficiency is expected to play a significant role in addressing energy problems for China. However, the ambiguous understanding of

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China’s building energy consumption has impeded the effective promotion and implementation of attempts to improve its building energy efficiency. Therefore, an estimation model of building energy

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consumption for China has been established from a life cycle perspective to determine the energy

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consumption in the building sector. By the comprehensive analysis carried out above, we obtain the following conclusions as well as policy implications:

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1) China’s building energy consumption throughout the life cycle increased from 738.64 Mtce to

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1655.19 Mtce over the period of 2001-2013 at around 7% of annual average growth rate. To curb the mounting energy demand of buildings in the life cycle, a wide range of policies for building energy

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conservation and efficiency should be deployed on the national level. Particularly, more financial support is required to ensure the effective implementation of building energy strategies.

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2) Building energy consumption during the life cycle accounted for about 43% of the total energy

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consumption and about 46% of the final energy consumption in China for recent years. The building sector is of great significance to the achievement of targets for China’s energy conservation and emission reduction. A comprehensive and elaborated information system of building energy consumption is desirable for better understanding of energy consumption components and decision-making of the government in building energy efficiency. 3) Building operation energy consumption, occupying a predominant place in building life-cycle energy of China, has remained relatively stable after a mild growth since 2006. However, the proportion of energy used in the operation stage to energy consumption in the whole life cycle has 19

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presented an uninterrupted decline. Energy efficient policies and measures for electrical appliances and indoor heating could be prioritized in order to reduce the operating energy consumption of buildings such as popularizing the energy efficiency labeling system and heightening the energy-saving

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awareness of residents. 4) Energy consumption of manufacturing building materials has boosted at a growth rate of 12.3%

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annually. Chances are that the building materials production energy will go up further in future for

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China, which means more focus should be drawn on the stage of building materials manufacturing. Building materials, especially energy-intensive materials such as steel and cement, should be included

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in the building energy system with preferential policy aiming to improve energy efficiency of the

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industry.

5) Energy consumption of rural residential buildings is a major contributor to operation energy

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consumption in buildings, but it has been overlooked for a long time. Due to a lack of statistical information on non-commercial energy (e. g. straw and fuel wood), most studies did not take energy

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consumed in rural residential buildings into consideration, which led to a substantial underestimation of

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operation energy of buildings in China. Hence, it is imperative that the government enacts related policy and regulation for encouraging the rural residents’ behavior of energy saving, revealing energy consumption information of households and controlling energy consumption scale of rural residential buildings.

Acknowledgement

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The authors gratefully acknowledge the financial support from the "Strategic Priority Research Program" of the Chinese Academy of Sciences (XDA05150600), National Natural Science Foundation

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of China (71020107026, 71273031).

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of

Housing

and

Urban-Rural

Development

of

China,

available

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[40] M.Y. Han, G.Q. Chen, L. Shao, et al., Embodied energy consumption of building construction engineering: case study in E-town, Beijing, Energy and Buildings 64 (2013) 62-72. [41] Y. Zhang, J. Fei, Discussion on the urgency of impelling building rubble recycles in China, Shanxi

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Architecture 36 (22) (2010) 352-353. (in Chinese)

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List of Table Captions: Table 1: Energy consumption situation of construction industry in China (2001-2013) Table 2: Energy consumption of urban residential buildings in China (heating excluded, 2001-2013)

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Table 3: Energy savings from recycling in China (2001-2013)

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Table 1 Energy consumption situation of construction industry in China (2001-2013) Floor space under construction (billion m2 )

Energy consumption per unit area (kgce/m2)

2001

22.55

1.88

11.97

2002

24.10

2.16

2003

27.21

2.59

2004

31.15

3.11

2005

34.03

3.53

2006

37.61

2007

41.28

2008

38.13

2009

45.62

2010

53.09

2011

58.72

2012 2013

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Year

Energy consumption of construction industry (Mtce)

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11.18

10.02 9.65 9.17

4.82

8.56

5.31

7.19

5.89

7.75

7.08

7.50

8.52

6.89

61.67

9.86

6.25

64.80

11.45

5.66

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4.10

M

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10.49

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Table 2 Energy consumption of urban residential buildings in China (heating excluded, 2001-2013)

2001

97.41

6.36

91.05

2002

103.17

6.99

96.18

2003

118.88

8.42

110.46

2004

136.79

11.89

124.90

9.02

2005

153.92

13.33

140.59

9.58

2006

170.35

15.56

154.79

9.91

2007

190.22

19.00

171.22

10.27

2008

196.15

20.78

175.37

9.93

2009

206.30

23.74

182.56

9.43

2010

207.07

28.53

178.54

8.44

2011

222.42

33.85

188.57

8.35

2012

238.01

37.87

200.14

8.55

40.71

210.34

8.72

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2013

251.05

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Urban residential buildings consumption (Mtce)

pt

Year

Transportation consumption (Mtce)

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Energy consumption per unit area (kgce/m2)

Residential consumption (Mtce)

M

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8.46 7.82 8.44

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Table 3 Energy savings from recycling in China (2001-2013) PE (Mtce)

RE (Mtce)

2001

207.73

10.39

2002

231.50

11.57

2003

277.22

13.86

2004

323.48

2005

362.23

2006

450.27

2007

504.79

2008

517.21

2009

562.65

2010

628.93

2011

713.65

35.68

754.57

37.73

834.92

41.75

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18.11

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22.51 25.24 25.86 28.13 31.45

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2013

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2012

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Year

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List of Figure Captions Fig. 1: General approaches to determining national building energy consumption (adapted from [16])

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Fig. 2: Life cycle boundaries of a building

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Fig. 3: Estimation framework of life cycle energy of buildings

Fig. 4: Energy for building materials production in China (2001-2013)

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Fig. 5: Energy consumption intensity for buildings under construction in China

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(2001-2013)

Fig. 6: Energy for centralized heating in northern cities of China (2001-2013)

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Fig. 7: Energy consumption of public buildings in China (heating excluded,

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2001-2013)

Fig. 8: Energy consumption of rural residential buildings in China (2001-2013)

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Fig. 9: Energy consumption of building operation stage in China (2001-2013)

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Fig. 10: Uninterrupted growth of life cycle energy consumption in China’s building sector during 2001-2013

Fig. 11: Life cycle energy of buildings and its proportion in China (2001-2013) Fig. 12: Component percentages of China’s building energy consumption throughout the life cycle (2001-2013)

Fig. 13: Changes in the steel and cement output and the construction area of China during 2001-2013 Fig. 14: Building energy consumption and building area of China during 2001-2013 Fig. 15: Structure of building operation energy consumption in China 30

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Fig. 1. General approaches to determining national building energy consumption

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(adapted from [16])

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Fig. 2. Life cycle boundaries of a building

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ed

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Fig. 3. Estimation framework of life cycle energy of buildings

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Fig. 4. Energy for building materials production and floor space of buildings

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pt

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under construction in China (2001-2013)

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Fig. 5. Energy consumption intensity for buildings under construction in China

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pt

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(2001-2013)

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Fig. 6. Energy for centralized heating in northern cities of China (2001-2013)

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Fig. 7. Energy consumption of public buildings in China (heating excluded,

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2001-2013)

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Fig. 8. Energy consumption of rural residential buildings in China (2001-2013)

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Fig. 9. Energy consumption of building operation stage in China (2001-2013)

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Fig. 10. Uninterrupted growth of life cycle energy consumption in China’s

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building sector during 2001-2013

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Fig. 11. Life cycle energy of buildings and its proportion in China (2001-2013)

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Fig. 12. Component percentages of China’s building energy consumption

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throughout the life cycle (2001-2013)

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Fig. 13. Changes in the steel and cement output and the construction area of

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China during 2001-2013

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Fig. 14. Building energy consumption and building area of China during

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2001-2013

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Fig. 15. Structure of building operation energy consumption in China

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Highlights: 1) We estimate China’s energy consumption in the building sector from 2001 to 2013.

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2) China’s building energy consumption has increased about 7% annually since 2001. 3) Buildings’ life-cycle energy accounted for over 40% of China’s total energy use.

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4) Buildings' operation energy occupied a predominant place in total life-cycle energy.

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5) More focus should be drawn on the manufacturing stage and rural buildings of

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China.

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