A holistic low carbon city indicator framework for sustainable development

Applied Energy xxx (2016) xxx–xxx

Contents lists available at ScienceDirect

Applied Energy journal homepage: www.elsevier.com/locate/apenergy

A holistic low carbon city indicator framework for sustainable development Sieting Tan a,c,⇑, Jin Yang b,d,e,⇑, Jinyue Yan c,e,⇑, Chewtin Lee a, Haslenda Hashim a, Bin Chen f a

Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia School of Humanities and Economic Management, China University of Geosciences, Beijing 100083, China c School of Sustainable Development of Society and Technology, Mälardalen University, SE-72123 Västerås, Sweden d Ningbo RX New Materials Technology Co., Ltd., Ningbo 315200, China e School of Chemical Engineering and Technology, Royal Institute of Technology, SE-10044 Stockholm, Sweden f State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing 100875, China b

h i g h l i g h t s
Assessment of the criteria for a range of low-carbon city (LCC) indicators at global level.
Establishment of an LCC indicator system covering the holistic perspectives of sustainable development.
The indicator system benchmark values for the standardization of cities.

a r t i c l e

i n f o

Article history: Received 25 September 2015 Received in revised form 6 March 2016 Accepted 13 March 2016 Available online xxxx Keywords: Low-carbon city (LCC) Indicator system Ranking Benchmarking

a b s t r a c t Many cities are pursuing the low-carbon practices to reduce CO2 and other environmental emissions. However, it is still unclear which aspects a low-carbon city (LCC) covers and how to quantify and certify its low carbon level. In this paper, an indicator framework for the evaluation of LCC was established from the perspectives of Economic, Energy pattern, Social and Living, Carbon and Environment, Urban mobility, Solid waste, and Water. A comprehensive evaluation method was employed for LCC ranking by using the entropy weighting factor method. The benchmark values for LCC certification were also identified. The framework was applied to 10 global cities to rank their low-carbon levels. The comparison of cities at different levels of economic, social, and environmental development enhances the holistic of the study. The results showed that Stockholm, Vancouver, and Sydney ranked higher than the benchmark value, indicating these cities achieved a high level of low-carbon development. São Paulo, London, and Mexico City are still in the slow transition towards LCC. Beijing and New York each has much lower LCC level than the benchmark value due to the poor environmental performance and infrastructure supports caused by intensive human activities. The proposed indicator system serves as a guideline for the standardization of LCC and further identifies the key aspects of low-carbon management for different cities. Ó 2016 Elsevier Ltd. All rights reserved.

1. Introduction Since the inception of ‘‘low-carbon economy” by the UK white paper ‘‘Our Energy Future: Creating a Low-Carbon Economy” in

⇑ Corresponding authors at: Faculty of Chemical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor, Malaysia (S. Tan), School of Humanities and Economic Management, China University of Geosciences, Beijing 100083, China (J. Yang), School of Sustainable Development of Society and Technology, Mälardalen University, SE-72123 Västerås, Sweden (J. Yan). E-mail addresses: [email protected] (S. Tan), [email protected] (J. Yang), [email protected] (J. Yan).

2003, low-carbon practices had been widely conducted and international cooperation was further emphasized. In recent years, the outcome of the landmark United Nation (UN) conference on climate change held in December 2009 in Copenhagen was a step forward with the agreement of Copenhagen Accord by setting an objective of limiting the increase in global temperature to 2 °C above pre-industrial levels. However, a study published in the journal of Environmental Research Letters found that the Accord’s voluntary commitments would probably result in a dangerous increase in the global average temperature of 4.2 °C over the next century [1]. The 2 °C goal can only be achieved by vigorous implementation of commitments in the period until 2020 and much

http://dx.doi.org/10.1016/j.apenergy.2016.03.041 0306-2619/Ó 2016 Elsevier Ltd. All rights reserved.

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S. Tan et al. / Applied Energy xxx (2016) xxx–xxx

stronger action thereafter [2]. To achieve the 2 °C goal, a farreaching transformation of the global energy system and lifestyle are required. Specifically, low-carbon development strategies should focus on the holistic perspective of economic, institutional and technological aspects. Cities are responsible for 70% of global CO2 emissions [3]. Cities are the basic unit of economic development and growth engines of the future should play a great role in the low-carbon development. The changing climate would also cause severe impacts on city, as they hold the increasing majority of the population and productive assets. The term ‘‘Low-carbon City” (LCC) emerged in response to the growing demand of carbon reduction and climate change alleviation of cities. Now, low-carbon practices have been widely conducted at a city level. It was reported that approximately 1050 cities in the United State, 40 cities in India, 100 cities in China, 83 cities in Japan established an objective of low-carbon development under their city’s development blueprint [4,5]. In a report of The C40 Cities Climate Leadership Group (C40), a network of the world’s megacities taking action to reduce greenhouse gas (GHG) emissions, estimated that about 93% of C40 Cities seat climate change responsibility at the highest level, 62% of C40 Cities had developed a climate change action plan, 50% of C40 Cities had a dedicated council or steering committee, and 57% of C40 Cities had specific GHG reduction targets for citywide emissions [3]. Table 1 shows the low-carbon goals and actions set by the representative mega cities. Despite of aggressive low-carbon targets have been established, there are remaining issues to be solved. Low-carbon development takes in diversified forms, for instance, Copenhagen focused on the promotion of renewable energy applications while London emphasized on energy efficiency programs. Regardless, the concept of LCC refers to not only GHG emissions but also development of economic, environmental and social aspects. Thus, a comprehensive understanding of LCC is the first step of low-carbon development. In addition, long-term low-carbon goals of various cities have been set. However, is the city low-carbon goal reasonable? To justify its feasibility, the low-carbon development status should also be well

acknowledged. Hence, it is desirable to develop a standard LCC indicator framework capable of evaluating the low-carbon level of cities under different socio-economic situations. Apart from that, the applicability and implementation of an indicator tool or method should be addressed. Many indicator systems have been developed to analyze the sustainable development of a city, but it requires a complicated set of input data that are often difficult to collect. Although this approach seems comprehensive and complete in principle but faces the difficulties for the application or uncertainties due to lack of input data. Therefore, this study aims to present a comprehensive indicator system for the evaluation, implementation and standardization of LCC. The low-carbon levels of 10 world cities are measured and compared using the proposed indicator system. In addition, the benchmark value of the LCC provides a goal and lower limit of each indicator and is defined to identify the low-carbon level of a city. It can thereby shed light on the certification of LCC. The paper is organized as follows: Section 2 reviews the definition of LCC and the current progress of the LCC indicator system. Section 3 describes the framework and methodology of LCC evaluation and certification, with the discussion on the selection of case cities and data sources. It is followed by the results of LCC ranking in term of comparison and low-carbon certification. The conclusions are given in Section 5. 2. Literature review 2.1. LCC definition Although many countries and regions are already taking action to address the carbon emission issue, the term LCC is so new that a consensus has not yet been reached on how to define it. LCC is always related to the ultimate goal of sustainability. The concept of ‘‘sustainable development” which emphasizes the ‘‘development that meets the needs of the present without jeopardizing the ability of future generations to meet their own needs” was identified as the concept of LCC in earlier research [6]. Therefore, LCC is within

Table 1 Low carbon targets of typical megacities (Author’s compilation). City

Region

Targets

Actions

New York

Copenhagen

North America North America Europe

London

Europe

Rotterdam

Europe

To reduce GHG emissions by 30% by 2030 compared with the 1990 level To reduce GHG emissions by 25% by 2020 and 80% by 2050 compared with the 1990 level To reduce GHG emission by 20% in 2015 compared with the 2005 level To reduce 60% GHG emission by 2025 compared with the 1990 level To reduce 50% GHG emissions by 2025

Seoul

East Asia

To reduce GHG emissions by 40% by 2030 compared with the 1990 level

Tokyo

East Asia

To reduce GHG emissions by 25% by 2020 from the 2000 level

Iskandar Malaysia Johannesburg

East Asia

To reduce GHG levels by 50% by 2025

Africa

–

Sydney

Southeast Asia and Oceania Latin America

To reduce GHG emissions by 20% by 2012 and 70% by 2030 below 2006 levels

Improved the energy efficiency of building through high performance standards for new construction Launched the Chicago Climate Action Plan (CCAP) in September 2008 with 5 strategies and 35 actions for GHG emissions mitigation Integrated climate adaptation into all aspects of planning – from overall municipal planning to both local and sectoral plans A range of programs and investing unprecedented amounts in climate change programs within London Launched the Rotterdam Climate Initiative (RCI) to offer a platform for governments, organizations, companies and citizens to work together on the goals Addressing climate change issues through projects such as establishment of climate monitoring system; development of Seoul climate & energy map; development of GHG inventory; and launch of the Seoul Emission Trading System Specific policy directions were delineated in the Tokyo Climate Change Strategy and the Tokyo Metropolitan Environmental Master Plan, which marked a dramatic departure from the past and made progress toward achievement of the announced target It not only addresses the social and economic needs of burgeoning populations, but also the environmental challenges they face Climate Change Programs are reviewed every quarter as part of the Environmental Departmental Balance Scorecard and are discussed in Sub Mayoral Committee on Climate Change Launched the Sustainable Sydney 2030, which provides a long-term strategic vision of Sydney as Green, Globally Connected

To reduce GHG emissions by 30% by 2012 from 2005 levels

Launched the first comprehensive Climate Bill in Brazil and is under final discussions for creating its guidelines for a Climate Change Action Plan

Chicago

São Paulo

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S. Tan et al. / Applied Energy xxx (2016) xxx–xxx

the framework of sustainability and is an extension of current sustainable development theory and practice. Roseland suggested that the concept of LCC should be defined from a local perspective, but equalities within a framework of global sustainability [7]. Skea and Nishioka revealed the consensus of LCC as a city in which the lowcarbon development is adopted in the development plan and ensuring the development needs of all groups within society is met [8]. The LCC should provide an equitable contribution to stabilize the world concentration of CO2 and other GHG without harmful to the environment through large reduction of global emissions. It should also demonstrate a high level of energy efficiency with a low-carbon energy source and production while adopting lowcarbon consumption and behavior. To that extent, Dai stressed that the LCC should pose the pattern of city construction and social development that focus on reducing carbon emission and citizen’s behavior changing towards lower carbon emission without compromising their overall quality of life [9]. Hodson and Marvin provided another view of LCC with a resource constraints and energy security systems that decision makers set a target within the broader context of low-carbon visions [10]. Wei suggested that LCC should be planned within the context of sustainable development planning and implementation. LCC is part of the global ecological system, requiring coordinated action at multiple scales (global to local), but oriented around local management within a global framework [11]. There are a variety of other terms contribute to the broader LCC discourse, as shown in Table 2. They may be used effectively as a synonym for LCC, or the individual terms overlap in meaning, but still signal different emphases in terms of aspirations, technologies, and governance.

Table 2 Similar concepts to LCC. Terms

Definition

Examples

Sustainable City

– A city with the connections among social equity, economic productivity, and environmental quality to meets the needs of the present without compromising the ability of future generations to meet their own needs [6,12].

1. Malmö, Sweden

Eco-city

– A city where human beings can exist in harmony with nature therefore greatly reducing ecological footprint [13] – A city that creates economic opportunities for their citizens in an inclusive, sustainable, and resource-efficient way, while also protecting and nurturing the local ecology and global public goods, such as the environment, for future generations [14]

1. ‘‘Sino-Singapore Tianjin Eco-city, China 2. City of Copenhagen, Denmark 3. Stockholm, Sweden 4. Yokohama, Japan

Smart city

– The safe, secure, environmental and efficient urban center of the future with advanced information and communication technologies (ICT) to stimulate sustainable development in the economic growth and a high quality of life [15,16]

1. Barcelona, Spain 2. Luxembourg

Carbon neutral city

– Similar to ‘LCC’ except defined more strictly as a city which offsets GHG emissions such that its net emissions is zero.

1. Melbourne, Australia

Zero carbon city

– More specifically to a city which produces no GHG and is run exclusively on energy from renewable sources

1. Masdar City, United Arab Emirates 2. Dongtan, China

3

2.2. Review on LCC indicator system Most of the current works related to the topic of LCC focused on carbon footprint accounting and LCC implementations [17–20]. The emphasis of LCC varies in different goals set draw an attention to the question to value and compare the low-carbon degrees of cities in order to ensure development are moving towards the set direction. Therefore, an indicator system is necessary, which guides the low-carbon strategy, urban planning and implementation, along with an implementable policy framework. In terms of indicator systems of LCC, most of the studies focused on the sectoral indicator, especially in energy sector. For instance, Portugal-Pereira and Esteban developed a series of indicators to assess the electricity generation security of supply under different energy portfolios in Japan [21]. Eicker et al. investigated the energy efficiency in building by a simulation tool to assess the energy demand and supply options as a function of the availability of geometry, building standard and use data [22]. Iddrisu and Battacharyya proposed a composite index, SEDI (Sustainable Energy Development Index), to assess the sustainability level of both intra- and inter-generational energy needs [23]. Sharma and Balachandra evaluated the sustainability of the electricity system based on hierarchical indicator framework and validated it for India’s national electricity system. They prioritized and quantified 85 indicators under four dimensions of sustainability of electricity system [24]. A few of the studies focused on the other sector for low-carbon development such as economic consumption [25], waste [26–28], and transportation [29]. Sectoral indicator systems fail to assess a city’s low-carbon status in a different dimension. In the year 2012, a low-carbon eco-city evaluation tool (ELITE) was developed by Lawrence Berkeley National Laboratory to evaluate cities’ performance by comparing the cities against benchmark performance goals as well as rank with other cities in China [30,31]. The ELITE measures the development progress of cities based on 33 key indicators selected to represent priority issues within eight primary categories. Price et al. also established an indicators system for China’s low-carbon cities using macrolevel economic indicators and end-use sectoral indicators. It emphasizes the measurement of carbon intensity based on economic and energy-related activities. Su et al. employed set pair analysis to compare 12 Chinese cities’ low-carbon development level [5]. Another indicator system was established by Yu, for a low-carbon economy evaluation system based on index system and empirical analysis for six cities in China [32]. Kalnins et al. developed a system to evaluate the transition of society towards low-carbon development for a case study of Latvia. The evaluations are based on the instrumental, political and educational process [33]. Apart from focusing on single country low-carbon indicator system, there are global indicator systems, e.g., Pamlin developed a Low-carbon Cities Development Index to benchmark a range of low-carbon development levels for cities [34]. The index focuses on three sectors that are policies, emission, and investment by three major indicators: direct emission, embedded emission, and global solution. A complex and comprehensive tool named LowCarbon Indicators Toolkit was established by the partnership of Regions for Sustainable Change (RSC), which is a complex and comprehensive tool for stakeholders from European regions who need to work with low-carbon indicators in the policy-making process [35]. Apart from the indicators on low-carbon development focus, there are other similar indicator systems developed for the LCC in the past decades, for instance the Global City Indicators [36], Siemens Green City Index [37], Sustainable Cities Index [38], Eco cities indicator [39–41], Urban Sustainability Index [42], and European Smart City [43], and others.

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S. Tan et al. / Applied Energy xxx (2016) xxx–xxx

2.3. Research gap on LCC indicator An indicator system is necessary to measure the movement of low-carbon development in a city and to benchmark the performance of different implementations of LCC. As discussed in Section 2.2, research has been conducted in both sectoral level and holistic level of LCC development. For sectoral level, the single goal of a single sector of low-carbon city was measured [21–29]. The sectoral indicators successfully addressed very specific sector in LCC development, however, it failed to integrate the entire elements in a low-carbon city. On the other hand, several holistic indicator systems were developed for LCC assessment [5,30–35]. The Existing indicator systems for LCC integrate different elements of a city but fail to address one important criterion – economic development of a sustainable LCC. The comparative analysis of different low-carbon development indicator systems and other similar indicator systems is presented in Table 3. As a summary, a few issues can be identified to improve the quality of LCC indicator systems: 1. Some of the indicator systems claimed to focus on the lowcarbon development, but the indicators are biased in a certain sector (i.e., energy sector, industry sector, or transportation sector) based on the percentage of sectoral carbon emission. As a holistic low-carbon development required effort from every sector in a city, sectoral-based LCC indicator system would not able to justify the low-carbon development of a city. 2. Some of the LCC indicator systems claimed to be holistic, however, most of the indicator systems do not include economic performance as one of the criteria. 3. While these indicator schemes share a common goal of capturing and measuring various dimensions of LCC, in the same time they differ significantly in terms of conceptual definitions, methodological approaches and modes of operation. Besides, most of the current indicator systems for LCC focus on the qualitative description of LCC. Even though some of them have quantified the LCC level of cities, the quantification places emphasis on carbon emission accounting and emission reduction potential evaluation. Therefore, there is a need to propose an appropriate and quantifiable indicator framework for LCC developed to address the objective of carbon emission reduction but also other objectives for the sustainable development of LCC. 3. Methodology A research framework is proposed for the evaluation and certification of LCC (Fig. 1). Information about the multiple factors and indicators are integrated to determine the comprehensive performance of the urban low-carbon development level in Step 1. The weight of each indicator in the LCC indicator system is also given in this step. Step 2 demonstrates the procedure of LCC ranking and benchmarking by selecting pilot cities. Based on the above steps, low-carbon development implications for cities are summarized in Step 3. An LCC indicator framework is thereby established.

development of a city towards its lower carbon emission target. The overview of LCC indicator framework is as presented in Fig. 2. The potential factors and indicators for different sectors are investigated, based on the availability of data resources as well as key parameters in the development of LCC. Once the sectors and their indicators have been identified and essential data has been collected and mortified, the next step is to construct a calculation model to determine the weighting factors of the LCC indicators. 3.2. Determination of weighting factors In typical indicator system evaluation approaches, weights of indicators reflect the relative importance in determining the overall performance. Entropy method, which firstly used in thermodynamics, can measure the amount of useful information with the data provided. Entropy weight is a parameter that describes the difference of the evaluating objectives to a certain attribute [45]. When the difference of the value among evaluating objects on the same indicator is high, i.e., the entropy is small, it illustrates that this indicator provides more useful information, and the weight of this indicator should be set correspondingly high [46]. The weighting factors are determined by the Entropy method in this study. Eqs. (1)–(6) depicts the calculation steps of Entropy method. The entropy weight will then be used in the scoring of the low-carbon level of a city, which represented in Eqs. (7) and (8). The first step is data normalization. The primary data set for LCC indicators consists of data with different dimensions and units. Therefore, the primary data should be processed and normalized before proceeding to the determination of indicator weight to minimize any data redundancy. Eqs. (1) and (2) are used to normalize data for the dimensionless process. Eq. (1) is used to normalize the positive indicator, where the larger the value of indicator, the better performance of the system. Eq. (2), on the other hand, is used for a negative indicator, the smaller the value of the indicator, the better the system performance.

ri;j ¼

xi;j  minj fxi;j g maxj fxi;j g  minj fxi;j g

ð1Þ

ri;j ¼

maxj fxi;j g  xi;j maxj fxi;j g  minj fxi;j g

ð2Þ

where r i;j is the normalized value of the jth object, ith indicator; xi;j is the original value of the jth object, ith indicator. The maxfxij g represents the maximum value in the set data of xij while minfxij g represents the minimum value in the dataset. Entropy method is used to determine the weight factor of each indicator. The entropy of the ith indicator is defined as Eq. (3):

Hi ¼ k

n X f i;j ln f i;j

where Hi is the entropy number of the ith indicator; n is the number of evaluated object in the study, i.e., the number of selected cities. The coefficient f ij and k are calculated in Eqs. (4) and (5).

,

3.1. LCC indicator framework

ð3Þ

j¼1

f i;j ¼ r i;j

n X ri;j

ð4Þ

j¼1

In this study, the LCC indicator framework analyses the lowcarbon development progress of cities on 20 quantitative indicators across seven categories, covering city economic development, energy pattern, social and living, carbon and environmental, urban mobility, waste, and water. Measuring the quantitative indicators helps to review the current environmental performance and

k ¼ 1= ln n

ð5Þ

when f ij ¼ 0, we suppose that f ij ln f ij also equal to 0. The weight of indicators wi , to a specific category is then calculated as Eq. (6)

Please cite this article in press as: Tan S et al. A holistic low carbon city indicator framework for sustainable development. Appl Energy (2016), http://dx. doi.org/10.1016/j.apenergy.2016.03.041

1

2 3

4

5 6

7

Indicator/Index/ Tool

Feature

Low-carbon ecocity evaluation tool (ELITE) Urban Low-Carbon Development Level Low Carbon City Development Index (LCCDI) Low-Carbon Indicators Toolkit

Evaluate cities’ performance by comparing them against benchmark performance in China

China

Using set pair analysis as a tool

China

Benchmark a range of climate work against other leading cities. A toolkits that compiled over 50 sets of indicators, indices and policy-aiding tools, relevant in one way or another to the low-carbon topic Measuring city’s performance including sustainability dimensions of 115 indicators Technical tool for assessing urban sustainability based on global data from 120 large cities

Global City Indicators Siemens Green City Index

Geographic boundaries

Element Organizational

Sector

Ref.

Economic

Social

Water

Energy

Transportation

Industrial processes

Agriculture

Waste &Water

X

X

X

X

X

X

X

X

[30]

–

X

–

–

X

X

–

–

X

[5]

Global

X

X

X

–

X

X

X

X

X

[34]

Global

X

X

X

X

X

X

[35]

Global

X

X

X

X

X

X

X

X

X

[36]

EU, Latin America, Asia Global

X

Partly

Partly

X

X

X

X

–

X

[37]

X

X

X

–

–

–

–

–

–

[38]

Europe

X

X

X

X

X

X

–

–

X

[42]

Measuring city’s development on 6 key field

Europe

X

X

X

–

X

X

X

–

–

[43]

–

–

–

[39– 41] [44]

Measuring the sustainability level of cities three demands of People, Planet and Profit Measuring urban sustainability based on a Pressure-StateResponse Model

10

Sustainable Cities Index Urban Sustainability Indicators European Smart City Eco City

A certification platform based on the urban environment

Global

X

X

X

–

–

–

11

ECO2 cities

Open-access framework to provide practical and scalable, analytical and operational framework for cities

Global

X

X

X

X

X

X

8

9

X

S. Tan et al. / Applied Energy xxx (2016) xxx–xxx 5

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Table 3 LCC indicators and other similar indicators.

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S. Tan et al. / Applied Energy xxx (2016) xxx–xxx

Sl ¼

X ðwi  r i;j  100Þ

ð7Þ

i¼1

LCC indicator selection

Weighting of indicators

Pilot cities selction

Bechmarking

where Sl is the low-carbon score of the lth category. The scores of each category are then rebased onto a scale of zero to 100. To obtain the overall LCC index score, the weights of each category are assigned evenly to 7 categories so that no category was given greater importance than any other. The overall score of the lowcarbon level of a city ST is described in Eq. (8).

ST ¼

s X ðSl  1=7Þ

ð8Þ

l¼1

3.4. Benchmark determination

Low carbon level ranking

Certification

LCC development implications

Fig. 1. The implementation procedure of the LCC indicator framework.

, wi ¼ ð1  Hi Þ

m

m X Hi

! ð6Þ

i¼1

where m refers to the total number of indicators (m = 20). 3.3. Low-carbon degree evaluation This section introduces the methodology to aggregate scores of all of the underlying indicators. The low-carbon score is the score to determinate the level of low-carbon development of a city, through multiplication of the entropy weight, wi, with the dimensionless value, rij. The indicators are first aggregated by category layer, creating a score Sl for each, as shown in Eq. (7).

Once the LCC indicator system was established, we set a benchmark for each indicator to evaluate the low-carbon performance of cities. The benchmark performs as a standard for low LCC certification. In this case, the data used for benchmarking represent the threshold of best performance for each chosen indicator. If all the benchmark values are satisfied by a city, this city can be certified as an LCC. To select the appropriate benchmark values, two principles should be balanced: (1) benchmarks have to sufficiently high as to preclude devaluing the efforts of strongly performing cities. If benchmarks were set too low, the incentive of high-performing cities to strive to improve further the low-carbon performance will be weakened. (2) If benchmarks were set too high, a city’s performance levels could be observed to clump at some much lower point and it would become difficult to differentiate superior city performance from average city performance [46]. To collect data used for benchmarking, the following sources are searched: (1) the benchmark values established by international organizations, for example, environmental emission limits set by WHO [47]; (2) the performances of top-performing environmental cities, eco-cities, and green cities, e.g., the energy and carbon performance in Green City Index proposed by Siemens; and (3) some international targets for developed countries, such as the renewable energy target set by Renewable Energy Directive sets rules for the EU. According to the aforementioned principles and sources, the benchmark values for LCC are preliminary set and presented in Table 4.

Fig. 2. The categories and the indicators for LCC. Note: (+) indicates the indicator is positive, i.e., the larger the value of the indicator, the better the system performance, while () indicates the indicator is negative, i.e., the smaller the value of the indicator, the better the system performance.

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S. Tan et al. / Applied Energy xxx (2016) xxx–xxx Table 4 Benchmark values for LCC indicators. Category

Indicator

Unit

Benchmark value

Source

Economic

E1. Per capita GDP E2. Proportion of tertiary industry to GDP E3. Carbon productivity

$/capita %

12616.00 66.00

The threshold for high income level [48] The proportion of tertiary industry of high income countries [49]

USD/ton

12244.00

The value of Copenhagen, which ranks the 1st of green cities all over the world [37]

EP1. Proportion of renewable energy

%

18.76

EP2. Energy intensity

MJ/USD

1.47

The value of Copenhagen, which ranks the 1st of green cities all over the world [37] The value of Copenhagen, which ranks the 1st of green cities all over the world [37]

Social and living

S1. Proportion of public green space S2. Population density

% Population/km2

50 4236.10

Environmental city Vienna [50] The value of Vienna, which is the most livable city [51]

Carbon and environmenta

C1. CO2 emission/capita C2. Nitrogen dioxide emission/capita C3. Daily sulfur dioxide levels C4. daily suspended particular matter levels

ton/person

lg/m3 lg/m3 lg/m3

2.19 40.00 20.00 20.00

[30] [47] [47] [47]

Urban mobility

M1. Public buses per capita

994.00

The value of Stockholm, which ranks the 1st in transportation sector for green cities all over the world [37] The value of Stockholm, which ranks the 1st in transportation sector for green cities all over the world [37] The value of Stockholm, which ranks the 1st in transportation sector for green cities all over the world [37]

Energy pattern

M2. Rail length per capita M3. Cars per capita Solid waste

Water a

Public buses/ million persons km/million persons Private cars/ persons

51.70 0.39

SW1. Solid waste generation per capita SW2. Share of waste collected and adequately disposed SW3. Share of waste to energy SW4. Share of material recycling

kg/capita/day

0.80

[52]

%

100.00

[52]

% %

0.50 60.00

[53] [53]

W1. Share of wastewater treated W2. Water consumption intensity

% L/capita/day

100.00 52.10

[30] [30]

carbon and environmental emissions are derived from production-based accounting.

3.5. Pilot cities selection

4.1. Entropy weighting scale

In this study, 10 major cities in the world are selected to perform the LCC indicator framework. The selection of cities was based on the parameters of population, geographical size, regional representation and stage of low-carbon sustainability plan (ideally at the implementation and monitoring stages). It includes Asia (Beijing, China and Tokyo, Japan), Oceania (Sydney, Austria), Africa (Johannesburg, South Africa), Europe (London, UK and Stockholm, Sweden), North America (Mexico City, Mexico, New York, US, and Vancouver, Canada), and South America (São Paulo, Brazil). Most are capital cities, large population hubs and business centers of the country and region. The 10 cities are representations of different level of cities. The comparison of cities at different levels of economic, social, and environmental development enhances the holistic of the study. The data was collected from publicly available official sources, such as national or regional statistical offices, local city authorities, local utility companies, municipal and regional environmental bureau, and environmental ministries. The data is generally for the year 2012, but when it was not available, they were taken from earlier years. If data are not available, estimates from national averages or other available, relevant data are applied. The collected data and sources are displayed in Table A1.

The calculated weights represent the relative importance of each index in the system, whose accuracy plays an important role in reflecting regional low-carbon development level. The

4. Results and discussions According to the 2012 statistical data of cities and the entropy weighting method presented in Section 3.2, the weights of lowcarbon city indicators are calculated. Subsequently, the lowcarbon levels of cities are evaluated based on the weighting scale.

Table 5 Entropy weight of each indicator and category. Category

Indicators

Weighting factor

Economic

E1. Per capita GDP E2. Proportion of tertiary industry to GDP E3. Carbon productivity

0.03916 0.01600 0.06145

Energy pattern

EP1. Proportion of renewable energy EP2. Energy intensity

0.07503 0.04421

Social and living

S1. Proportion of public green space S2. Population density

0.05429 0.03735

Carbon and environment

C1. CO2 emission/capita C2. Nitrogen dioxide emission/capita C3. Daily sulfur dioxide levels C4. Daily suspended particular matter levels

0.04068 0.04703 0.03296 0.04223

Urban mobility

M1. Public buses per capita M2. Rail length per capita M3. Cars per capita

0.07957 0.10521 0.03176

Solid waste

SW1. Solid waste generation per capita SW2. Share of waste collected and adequately disposed SW3. Share of waste to energy SW4. Share of material recycling

0.04668 0.04490

W1. Share of wastewater treated W2. Water consumption intensity

0.03543 0.04968

Water

0.06730 0.04909

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S. Tan et al. / Applied Energy xxx (2016) xxx–xxx

information entropy and its weight of each indicator in different categories were derived, as presented in Table 5. The highest weighting factor revealed the highest importance in the whole system and vice versa.

Table 6 Evaluation standard for LCC. Low-carbon Development Index

Category

>56 <56

Low-carbon City High-Carbon City

4.2. Overall performance of low-carbon city development Based on the aforementioned methodology, the LCC levels of selected cities are shown in Fig. 3. The benchmark city has a score of approximately 56, which represent the minimum score for an LCC. Accordingly, two classifications of the LCC development can be identified, as shown in Table 6. Cities with index scores higher than 56 can be certified as LCCs while cities with index scores lower than the benchmark city are defined as the High-carbon city. As shown in Fig. 3, there are three low-carbon cities with an index score of above 56, which includes Sydney, Vancouver, and Stockholm. Stockholm ranked the first in the LCC ranking system with the index score of 65.57. Vancouver and Sydney placed in the second and third, with the scores slightly higher than the benchmark city. The others cities are identified as High-carbon cities, including San Paulo, London, Mexico-city, Tokyo, Johannesburg, New York, and Beijing. Beijing ranked in the lowest level of the LCC with the score of only 34.53, which is 60% lower than the LCC level. 4.3. Low-carbon level in different development category This section highlights the low-carbon development performance across a range of key categories for the assessed cities, as presented in Fig. 3. The Economic category reflects the economic development of a city. Sydney stands in the strongest economic level. Stockholm and São Paulo performed at the middle level as compared to other cities. Beijing performed relatively poorly with the score of only 1.83, much lower than the average of the 10 cities. This low score is determined by the low-carbon productivity in Beijing which implies high human activity intensity, will finally lead to more resource consumption and environmental emissions. With respect to the category of Energy Pattern, Vancouver, Stockholm, São Paulo, and Johannesburg ranked at a relatively high level; while Beijing, New York, and Sydney are at a relatively low level. In the category of Carbon and Environment, Beijing shows again the poorest performance which implying the severe environmental problem in Beijing. High carbon emission per capita and

excessive PM2.5 emission are threatening the health of residents in Beijing. On the other hand, Stockholm, Vancouver, and Sydney show the best practices and greenest environment performance with relatively less carbon emission and air pollution. Tokyo and Stockholm rank – the first two places in terms of waste treatment and efficient water utilization. To identify if a city meets the LCC requirement, Table 7 shows detailed comparisons of low-carbon performances of selected cities with those of the benchmark city. Cells in gray indicate that the performance of the concerned city is better than the benchmark city in terms of a specific aspect (represented by indicators). On the contrary, cells in white mean the performance of the concerned city fails to meet the benchmark value. 4.4. City portrait on low-carbon development The section provides a detailed assessment on the city lowcarbon development level based on the LCC indicator results. Two cities out of the 10 pilot cities – Stockholm and Beijing are selected, as the two cities represent respectively the best and the worst performance in LCC development. 4.4.1. Stockholm Fig. 4 presents Stockholm’s performance in LCC indicator system. Stockholm ranks the best low-carbon development level among the ten selected cities with the total score of 65.57. The city excels in Water, Waste, Carbon and Environment, Economic, and Energy Pattern, with a higher score than the benchmark city and only setback in the category of Social and Living, as compared to the benchmark city. The result of LCC indicator system revealed Stockholm’s excellent performance in the Economic category, as its economy is dominated by the services sector. The city has a particularly high concentration of jobs in information technology, the healthcare industry and research while completely devoid of heavy industry, which has helped to make it one of the world’s cleanest cities

Fig. 3. Low-carbon development ranking of 10 cities and 1 benchmark city.

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S. Tan et al. / Applied Energy xxx (2016) xxx–xxx Table 7 LCC certification of cities.

Economic 100

low-carbon performances in these two categories are as good as the benchmark city.

80 Water

60

Energy pattern

40 20 0 waste

Social and living

Urban Mobility

Carbon & Environment

4.4.2. Beijing Beijing ranks the worst in terms of total low-carbon level among the selected cities. Out of the seven categories in LCC indicator system, the city performs best in Social and Living, but, defeated in the categories of Economic, Energy Pattern, Carbon and Environment, Waste, and Water, as compared to the benchmark city. The calculated low-carbon level of each category of Beijing is shown in Fig. 5. The city performs the best in the category of Social and Living, with above average rankings, reflecting the city’s vigilance in improving living. Beijing has the second lowest population

Economic 100

Stockholm

Benchmark city

Fig. 4. Low-carbon level of different categories in Stockholm and benchmark city.

80 Water

Energy pattern

60 40

[37]. Stockholm ranks the third in the category for energy, which is higher than the benchmark city. In Stockholm, 90% of the city’s energy source is renewable with 43% of hydropower and 47% of nuclear power [54]. However, Stockholm has high energy intensity due to the cold climate and high standard of living. In the category of Carbon & Environment, Stockholm strived the best with the score of 12.47. The CO2 emissions, at 2.95 t/capita in 2012, are relatively low compared to other developed cities such as London, New York, and Tokyo [37]. Also, air quality is very good with low suspended particular matter, NOx and SO2 emissions. In term of Solid Waste and Water categories, Stockholm has a century-long tradition of good wastewater and solid waste management. Nearly 100% of solid waste was collected adequately and treated properly through waste-to-energy or recycling while 100% wastewater is processed before recharged to river [55]. The

20 0 waste

Social and living

Carbon & Environment

Urban Mobility

Bejing

Benchmark city

Fig. 5. Low-carbon level of different categories in Beijing.

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10

Driving factor

Indicators

Unit

Benchmark city

Londona

Stockholmb

New Yorkc

Tokyod

San Pauloe

Bejingf

Vancouverg

Mexico cityh

Sydneyi

Johannesburgj

E

E1 E2 E3

$/capita % $/t

12616.00 66.00 12244.00

51978.00 88.90 10252.07

53941.00 80.20 18252.91

63238.00 91.90 1269.33

41446.00 78.40 8868.13

39799.00 76.00 28427.86

20275.00 77.30 2472.56

16768.79 81.00 3808.81

19940.00 77.20 13400.65

45377.00 82.40 37197.80

17418.00 80.30 11737.20

EP

EP1 EP2

% MJ/$

18.76 1.47

14.00 2.77

48.00 2.20

23.00 2.99

6.00 1.20

54.50 0.55

4.50 7.94

90.00 1.69

17.00 3.39

13.00 7.74

12.19 0.73

S

S1 S2

pop/km2

0.35 4236.10

0.38 4887.75

0.40 4800.00

0.14 10725.40

0.03 6000.00

0.01 7315.00

0.56 1261.00

0.12 5249.00

0.39 5954.20

0.46 372.40

0.22 2673.87

C

C1 C2 C3 C4

t/person ug/m3 ug/m3 ug/m3

2.19 40.00 20.00 20.00

5.07 37.00 0.00 22.00

2.96 13.32 2.45 15.00

6.35 49.82 7.34 23.00

4.67 39.50 5.70 33.10

1.40 47.00 4.00 35.00

8.20 52.00 28.00 121.00

4.40 39.48 3.14 4.82

1.49 60.00 13.00 93.00

1.22 9.00 20.00 9.00

4.44 33.00 16.00 98.00

M

M1 M2 M3

Public buses/M person km/M person Cars/person

994.00 51.70 0.39

903.00 52.50 0.31

994.00 51.70 0.39

521.00 44.80 0.21

162.00 33.60 0.18

7142.86 124.19 0.44

1071.00 38.00 0.25

3218.10 665.74 0.55

1357.16 403.08 0.40

474.00 70.50 1.50

1394.79 425.94 0.18

SW

SW1 SW2 SW3 SW4

kg/capita/d % %

0.80 100.00 0.50 60.00

0.56 51.00 0.21 34.00

0.28 100.00 0.49 25.00

0.87 44.00 0.22 30.40

1.09 100.00 0.80 23.20

0.55 100.00 0.35 1.00

0.52 95.40 0.10 37.00

0.15 57.00 0.25 45.00

0.49 100.00 0.00 56.00

0.09 100.00 0.10 57.00

1.10 98.00 0.00 3.30

W

W1 W2

% l/person/d

100.00 52.10

99.00 157.78

100.00 50.88

64.00 69.30

100.00 320.20

81.00 220.50

80.30 218.10

55.00 137.00

12.90 178.00

99.70 286.00

92.50 348.70

a Economist Intelligence Unit. (2011). European Green City Index: Assessing the environmental performance of Europe’s major cities. Siemens AG. http://www.siemens.com/entry/cc/features/greencityindex_international/all/en/pdf/ report_en.pdf (Accessed 21 June 2015). Greater London Authority – London datastore. http://data.london.gov.uk/topic (Accessed 21 June 2015). London Councils – fact and statistics. http://www.londoncouncils.gov.uk/who-runslondon/london-facts-and-statistics (Accessed 21 June 2015). b Economist Intelligence Unit. (2011). European Green City Index: Assessing the environmental performance of Europe’s major cities. Siemens AG. http://www.siemens.com/entry/cc/features/greencityindex_international/all/en/pdf/ report_en.pdf (Accessed 21 June 2015). Stockholm County Facts and Figures. (2013). http://www.statistikomstockholm.se/attachments/article/21/facts%20and%20figures%202013_webb.pdf (Accessed 23 June 2015). Statistics Sweden. http://www.scb.se/en_/ (Accessed 23 June 2015). c New Yok Coucil – Open data. https://nycopendata.socrata.com/data?cat=environment (Accessed 23 June 2015). Economist Intelligence Unit. (2011). US and Canada Green City Index: Assessing the environmental performance of 27 major US and Canadian cities. Siemens AG. http://www.siemens.com/entry/cc/features/greencityindex_international/all/en/pdf/report_northamerica_en.pdf (Accessed 14 August 2015). d Economist Intelligence Unit. (2011). Asian Green City Index: Assessing the environmental performance of Asia’s major cities. Siemens AG. http://www.siemens.com/entry/cc/features/greencityindex_international/all/en/pdf/report_ asia.pdf (Accessed 20 July 2015). Statistics Division of Bureau of General Affairs, Tokyo. http://www.toukei.metro.tokyo.jp/homepage/ENGLISH.htm (Accessed 20 July 2015). e Economist Intelligence Unit. (2011). Latin American Green City Index: Assessing the environmental performance of Latin America’s major cities. Siemens AG. http://www.siemens.com/entry/cc/features/greencityindex_international/all/en/pdf/report_latam_en.pdf (Accessed 28 July 2015). f Beijing Statistical Yearbook (2013). Economist Intelligence Unit. (2011). Asian Green City Index: Assessing the environmental performance of Asia’s major cities. Siemens AG. http://www.siemens.com/entry/cc/features/greencityindex_international/all/en/pdf/report_asia.pdf (Accessed 28 July 2015). g City of Vancouver – Open data catalog. http://data.vancouver.ca/datacatalogue/index.htm (Accessed 3 August 2015). Economist Intelligence Unit. (2011). US and Canada Green City Index: Assessing the environmental performance of 27 major US and Canadian cities. Siemens AG. http://www.siemens.com/entry/cc/features/greencityindex_international/all/en/pdf/report_northamerica_en.pdf (Accessed 14 August 2015). h Economist Intelligence Unit. (2011). Latin American Green City Index: Assessing the environmental performance of Latin America’s major cities. Siemens AG.. http://www.siemens.com/entry/cc/features/greencityindex_international/all/en/pdf/report_latam_en.pdf (Accessed 15 August 2015). i City of Sydney – Green Environmental sustainability progress report July – December. (2014). http://www.cityofsydney.nsw.gov.au/__data/assets/pdf_file/0018/227070/Green-Report-July-to-December-2014.pdf (Accessed 2 September 2015). City of Sydney – Data provided for the CDP Cities 2015 Report. https://www.cdp.net/Documents/cities/2015/sydney-in-focus.pdf (Accessed 2 September 2015). j Economist Intelligence Unit. (2011). African Green City Index: Assessing the environmental performance of Africa’s major cities. Siemens AG.. http://www.siemens.com/entry/cc/features/greencityindex_international/all/en/pdf/ report_africa_en.pdf (Accessed 15 August 2015). City of Johannesburg- State of the Environment Report. (2009). http://www.joburg.org.za/index.php?option=com_content&task=view&id=3959&Itemid=114 (Accessed 2 September 2015).

S. Tan et al. / Applied Energy xxx (2016) xxx–xxx

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Table A1 Detail data and sources used for LCC Indicator system.

S. Tan et al. / Applied Energy xxx (2016) xxx–xxx

density, with just 1261 inhabitants/km2 [56]. The proportion of green spaces of Beijing is 56% [37], which is the highest among all the selected cities. Beijing scored only 1.83 in the Economic category of LCC indicator system, much lower than the average of the 10 cities. This low score is determined by the relatively low per capita GDP, proportion of tertiary industry to GDP, and carbon productivity. Among these three indicators, the carbon productivity has the largest impact on low carbon level of Beijing. Low carbon productivity, i.e., low economic output per carbon emission, implies that the economic development is extensive at the cost of high carbon emissions. Besides, Beijing ranks below average in the Energy Pattern category. The lowest score in energy pattern category of Beijing is determined by high energy intensity and low renewable energy proportion. Beijing’s energy intensity (7.94 MJ/US$GDP) largely exceeds the benchmark limit [56], indicating the inefficiency of energy use. In addition, the proportion of renewable energy in total energy use in Beijing is also relatively small. In term of Carbon and Environment category, Beijing scored much lower than the other cities, implying the severe environmental problem in Beijing. Beijing has a carbon emission per capita of 8.2 t/person [37], the highest value among the others cities. For air quality, especially SO2 emission and particular matters emission, Beijing is much higher than the other countries. Beijing has a well-constructed public transportation system, which is at the same level with the benchmark city. However, waste and water treatment and reuse still fall behind many other cities.

5. Recommendation for further analysis of LCC development level The constructed indicator system embraces basic elements of LCC development. Through entropy weighting and synthetic evaluation, various data was integrated to obtain a comprehensive state of urban low-carbon development level, which assigns an assessed city a ranking among different cities in terms of urban low-carbon development level. The proposed LCC indicator framework also provides a benchmark for the quantification of LCC. Based on the results of this study, only Stockholm, Vancouver, and Sydney have a higher LCC level as compared to the benchmark city and hence those could be quantified as a LCC. Moreover, based on analytical diagnosis, situations of specific indicators were investigated, which may help identify key problems of the cities. From the comparison of LCC level of Stockholm and Beijing, good practices of Stockholm in areas of waste treatment, renewable energy development could be referred to by low-ranking cities such as Beijing. To further deepen the LCC development of Stockholm, the reduction of energy intensity should be emphasized. In order to achieve the vision of LCC, Beijing should aggressively reduce the current fossil fuel-dominated practice towards more clean and renewable energy, emphasize air quality control actions, and make efforts on waste reuse, especially waste to energy programs. The preliminary evaluation of low-carbon development level focuses on the overall ranking as well as the detailed categories based discussion. However, the LCC development level may differ for different types of cities depending on the natural condition, resources endowment, and political situation of each city [57]. Therefore, a more detailed analysis could be conducted on a specific type of cities (e.g., economy-limited city, resource-limited city, or environment-limited city) in the future to obtain more effective management options. The uncertainty in this research derives from (1) the complexity and dynamic of city development and (2) the uncertainties in data collected. Uncertainty analysis will be conducted using mathematical models in future studies. In addition, sensitivity analysis of

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individual cities will be performed in future work to identify the key parameters in this framework which influencing the lowcarbon level the most. Flexibility to regulate the key parameters may help the stakeholders to better design, manage and monitor the progress of LCC development. 6. Conclusion A new framework of low-carbon city (LCC) indicator was developed for the comprehensive evaluation and analytical analysis of LCC development. The proposed framework considers different development categories including economic, social and environmental factors with different indicators. Entropy weighting and comprehensive evaluation method were used to perform the low-carbon development evaluation for 10 selected cities across different regions in the world. An LCC index is identified and used as the benchmark value for city’s lowcarbon development. The indicator system is able to facilitate and visualize the comparison of low carbon level of cities with different level of economic, socio and environmental development. The results give impetus to every city to learn from each other as to continuously improve their low-carbon levels. Acknowledgements This study was supported by the National High Technology Research and Development Program of China (No. 2015AA050403), the Scientific Research foundation of China (No. 35932015025), the Ministry of Higher Education (MOHE), Malaysia, and Universiti Teknologi Malaysia (UTM) (Vot. No. Q.J13000. 10h67). The acknowledgement also dedicated to the EU-Erasmus Mundus IDEAS Project for the scholarship to first author. Appendix A See Table A1. References [1] Rogelj J, Chen C, Nabel J, Macey K, Hare W, Schaeffer M, et al. Analysis of the Copenhagen Accord pledges and its global climatic impacts – a snapshot of dissonant ambitions. Environ Res Lett 2010;5:034013. [2] International Energy Agency (IEA). World energy outlook 2010; 2010 [accessed on 2014-0108]. [3] Carbon Disclosure Project (CDP). Cities 2011 global report on C40 cities; 2011 [accessed on 2014-1-15]. [4] Gomi K, Shimada K, Yuzuru M. A low-carbon scenario creation method for a local-scale economy and its application in Kyoto city. Energy Policy 2010;38:4783–96. [5] Su M, Li R, Lu W, Chen C, Chen B, Yang Z. Evaluation of a low-carbon city: method and application. Entropy 2013;15:1171–85. [6] United Nation World Commission of Environment and Development. Our common future. Oxford University Press; 1987. [7] Roseland M. Eco-city dimensions: healthy community, healthy planet. New Society Publishers; 1997. [8] Skea J, Nishioka S. Policies and practices for a low-carbon society. Clim Policy 2008;12:5–16. [9] Dai YX. The necessity and governance model of developing low carbon city in China. Chin J Popul Res Environ 2009;19(3):12–7 [in Chinese]. [10] Hodson M, Marvin S. World cities and climate change: producing ecological security. McGraw Hill; 2010. [11] Wei T. Building low-carbon cities through local land use planning: towards an appropriate urban development model for sustainability, Thesis; University of Nebraska-Lincoln; 2011. [12] Rogers R. Cities for a small planet. 1st ed. Boulder: Westview Press; 1998. [13] Register R. Eco-city Berkeley: building cities for a healthy future. Berkeley: Berkeley Hills Books; 1987. [14] World Bank. Eco2 cities: ecological cities as economic cities program; 2009 [accessed on 2014-1-15]. [15] Caragliu A, Bo C, Nijkamp P. Smart cities in Europe. Res Memo 2009:48.

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