Abstract

Introduction

Review of literature on the current understanding and ongoing debate of smart cities

Method and data

Results and discussion

Conclusion

Declarations

References

Abstract

     Smart city is one of the fastest growing socio-economic and scientific initiative in the world. Still, it is only in principle and a mere blueprint for many developing countries. This study reviews literature on smart city in Nigeria and developing countries. Our aim is to explore ways to improve the quality of Nigeria’s urban areas, based on recent research on the concept of smart city and its implementation. We summarise key research findings, and gather evidence that shows what composition of urban governance, social, economic, and environmental factors, that would influence actualising a smart city in Nigeria. Although knowledge has grown tremendously in the current literature on the definition, significance, governance, policy, and implementation of a smart city, its significance in Nigeria and other developing countries is supplemental. As an environmentally friendly initiative, a smart city will support urban sustainability and livelihood in Nigeria in a myriad of ways—environmental protection, and mainstream urban services, including public security and safety, access to quality health care, efficient power supply, clean water distribution, assets management, smart transportation, etc. However, despite her unique traditional urban agglomeration trends, Nigeria is unambitious and constrained towards actualising a smart city. Actualising a smart city in Nigeria and other developing countries would require radical and ambitious policies on development of human and infrastructural capacity, as well as institutional reinforcement. This highlights the need for more research, of which we are optimistic that the findings of this research will support with its new insight and clear guidelines.

Introduction

     A smart city is modern architectural philosophy, focusing on the use of information and communication technology (ICT) to solve problems endogenous to the city, and to power vital activities. It represents a major transformation from the traditional urban agglomeration to a twenty-frst-century metropolis, which advances city functions, promotes economic growth, and improves the quality of life for citizens (Bakıcı et al., 2013). One obvious beneft of a smart city is the level of government response to the needs and well-being of citizens through positive interaction between the government and citizens, aided by technology-driven policies and services. When we look at some of the smart cities in the world today for example Singapore, San-Diego, Barcelona, and Hong Kong, we could fnd that smartness of cities creates applications and urban services that combine technology and promotes the development of policies and practices to address the social, economic, and environmental challenges facing today’s urban areas (Su et al., 2011).

Conclusion

     A smart city represents a shift both in mindset and architectural framework from the traditional agglomeration of roads, public utilities, and amenities to a modern system that uses big data and ICT to enhance the livelihood of the citizens and government policy and program of service delivery within the city. This is a major incentive for research and policy towards the sustainable development of cities. There is also an opportunity to tackle urban scenic distortion and to provide a more dynamic and diversifed science to address common issues – such as climate change, increasing frequency, and severity of crimes, social disorders, and disasters – arising from urban agglomerations and the burgeoning human population in cities.

For the developing countries (DCs) such as Nigeria – the focus of this study – a smart city’s conceptualization is slightly skewed because of the vagaries of challenges to its actualization. Thus, the idea of a smart city is still more utopian than realistic. However, the future of the DCs is arguably a smart city because of the complex urbanizations and predictions that places within the DCs will contribute signifcantly to the global urban populations, which is estimated at 90% of the global population by 2050. Therefore, to address the attendant problems that prevail presently in the DCs’ urban areas – which include environmental, economic, and human development issues – a smart city is a potent option.

1. Introducing citizen science

2. Citizen science and the Sustainable Development Goals

3. Methodology

4. Results

5. Discussion

6. Conclusions

Appendix 1. Summary of the survey instrument

Appendix 2. Citizen Science networks, platforms and projects which received the survey

References

Abstract

Citizen Science, known as the participation of individuals and groups in scientific processes, is an increasingly growing discipline, which can contribute for the achievement of the Sustainable Development Goals. The UN Agenda 2030 for Sustainable Development is all-inclusive, where every contribution is valid. Participation, partnerships, education, sustainable living and global citizenship, all of which can build on Citizen Science activities, are crucial for the Sustainable Development Goals. In this context, this study aims at exploring several collaboration channels for Citizen Science-related activities and the Agenda 2030. Challenges and critical aspects are discussed based on the opinions of practitioners collected through a comprehensive online survey. Furthermore, recommendations for future involvement are given on a framework of interactions at different levels for Citizen Science and the Agenda 2030.

Introducing citizen science

Citizen Science (CS) works alongside science, education, and civic engagement and is increasingly being a discipline in its own right (Science Europe, 2018). There are several definitions, but CS is often considered as the participation of lay people, individuals, or groups in scientific processes (Kullenberg and Kasperowski, 2016). These contributions differ from informal learning due to engagement in science-related processes (Jordan et al., 2012), such as modelling, new discoveries, observations, data collections and analyses, technological processes, and evidence-based policies (Raddick et al., 2009).

Citizen Science has existed for a long time, but it has especially expanded in recent years due to more collaborations between volunteers and researchers, emerging technologies and new ways of data collection such as crowdsourcing, digital sharing, online projects and social networks (Socientize, 2013). Common synonyms for CS are “amateur science,” “crowd sourced science,” “volunteer monitoring,” and “public participation in scientific research” (https://scistarter.org/citizen-science). A citizen scientist, without necessarily a scientific background, volunteers to collect or process data for scientific research (Silvertown, 2009). CS has changed the professional-amateur relationship because of an increased accessibility to the internet and tolerance of the web (Dowthwaite and Sprinks, 2019). The field of CS is growing towards scientific literature and policy making, but there is a need to foster trust in CS results, so to increase their use and consequently strengthen the field (Rasmussen, 2019).

1. Introduction

2. Literature review

3. Enabling technologies in smart city

4. Challenges and issues in realization of smart cities

5. Sustainable smart cities

6. Conclusions, discussion and future directions

Declaration of Competing Interest

References

Abstract

The technological interventions in everyday processes has led to the rise of Smart ecosystems where all aspects of everyday life like governance, transportation, agriculture, logistics, maintenance, education and healthcare are automated in some way or the other and can be controlled, managed and accessed remotely with the help of smart devices. This has led to the concept of Smart cities where Information Communication and Technology (ICT) is merged with the existing traditional infrastructure of a city which is then coordinated and managed using digital technology. This idea of smart cities is slowly but surely coming into reality as many countries around the globe are adopting this idea and coming up with their own model of smart cities. At the core of smart city lies the sensors and actuators embedded in the smart devices that sense the environment for facilitating effective decision making. The microcontrollers available in these devices are programmed to take decisions automatically based on the information received from the sensors. This involves integration of several information and communication technologies like artificial intelligence, protocols, Internet of things (IoT), wireless sensor network (WSN) etc. This paper discusses and extensively reviews the role of enabling technologies in smart cities. The paper further highlights the challenges and limitations in the development of smart cities along with the mitigation strategies. Specifically, three categories of challenges are identified namely technical, socio-economic and environmental giving specifics of each category. Finally, some of the best practices for attaining sustainable smart cities are provided.

Introduction

The cutting edge technological advancements in today’s world has helped realize the long awaited dream of a modern utopian world that aims to balance the traditional systems with advanced technological interventions. The technologies like artificial intelligence (AI), Internet of Things (IoT), machine learning (ML), deep learning (DL), cognitive computing and big data analytics have contributed immensely in the realization of this dream [1][2][3]. Smart city is one such hopeful project that has been adopted globally with an aim to make the lives of the habitants more convenient and inclusive [4][5].The idea is to use modern day technologies to convert every entity of a conventional city into an autonomous object performing its operation automatically without any substantial external help. All everyday processes like governance, policies, services and feedbacks are automated and the users are able to access these with the help of smart devices from anywhere around the globe. This automation has provided a decent help in curtailing the environmental hazards by means of applying environment friendly and cost-effective techniques. The core entities of a smart city consists of smart infrastructure, smart governance, smart policies, smart transportation, smart healthcare, smart agriculture, smart education, smart economy, smart environment, smart industry, smart energy and smart feedback mechanisms that helps to truly realize the concept of a smart city ecosystem [1][2][3][4][5]. The word “smart” refers to an automated mechanism which is adopted to perform the desired activity within a domain. For example, in a smart home all gadgets and electric equipment (like fans, tube-lights, washing machines, HVAC systems, ovens etc) are embedded with miniature sensory devices that are able to sense the surrounding environment, collect information and transfer that information to the processing hubs where decisions can be taken with the help of dynamic rules and regulations.

1. Introduction

2. The concept of the Internet of Things and the significance of building a smart city

3. Internet of Things architecture based on fog computing

4. Smart city architecture based on cloud computing technology

5. Experiments and analysis

6. Conclusion

References

Abstract

Fog computing and Internet of Things technology play a prominent role in the construction of smart cities, which can greatly promote the exchange and management of urban information. Emerging network technologies such as fog computing and the Internet of Things can be used to make it easier to build smart cities, which is conducive to the development of urban business, industry and other industries, as well as tourism and transportation management. Therefore, the realization of a smart city will greatly enhance the comprehensive development strength of the city. We analyze the advantages of fog computing and propose an IoT architecture based on fog computing, which effectively solves the problems of big data processing and network scalability. On this basis, a layered fog computing network architecture is proposed to make the city’s operation more coordinated, efficient and harmonious through various intelligent perceptions, information processing and network transmission means.

Introduction

With the increasing progress of science and technology, China’s urban construction has made new developments, especially after the application of Internet of Things technology and cloud computing technology, which optimizes all aspects of the city and achieves the goal of urban intelligent construction [1]. With the development of urbanization, smart cities have gradually become an inevitable development trend, so we need to focus on exploring the role of cloud computing and Internet of Things technology in smart cities and promote the realization of smart cities [2]. After exploring the theories of cloud computing, Internet of Things technology and smart cities, this paper determines the role of cloud computing and Internet of Things technology and then applies them reasonably to the construction of smart cities, ultimately promoting the rapid development of smart cities.

Fog computing can make full use of the distributed computing, storage, communication and control capabilities in the network environment. Through the resource sharing mechanism and collaborative service architecture, it can achieve a shorter service response time, stronger localized computing capability, lower data transmission load, safer decentralized service architecture, and faster and more accurate analysis, decision-making and control. With the continuous development, maturity and popularization of fog computing technology, the intelligent Internet of Things will become increasingly convenient and efficient. Fog computing and cloud computing will complement each other, provide everyone with accessible and ubiquitous intelligent services, and inject development power into the intelligent city where everything is interconnected.

1. Introduction

2. Research methodology

3. Material-based computational design (MCD)

4. Results and discussion

5. Conclusion

References

Abstract

Today material is the driving force in architectural design processes run by Computational Design (CD). The architect may lead the design process and its outputs by analysing material type and properties, as well as constraints, at the beginning of the process. This article reviews the state of the art in Materialbased Computational Design (MCD) and aims to analyse the role of materials in efficient and sustainable MCD processes. A set of critical projects developed over the past decade have been selected and grouped based on how material is incorporated into the process. In the process, three main categories are identified—namely, Material Performance, Informed Materials and Programming Materials. Based on predefined criteria on efficiency (E) and sustainability (S) in architectural design processes, the projects are analysed to calculate their E+S ratings. The analysis identifies two principal approaches implemented in MCD. One focuses on integrating material properties with other critical parameters—including form, performance and fabrication. The other concerns enhancing material properties by designing new materials. The analysis verifies that MCD generates both efficient and sustainable design solutions. By using CD in architectural design processes, existing materials can be re-interpreted and innovative materials can be produced to achieve new spatial experiences and meanings.

Introduction

The increasing influence of information technologies in the field of architecture over the last decade has defined a new relationship between material and architectural design in which material has become the principal driver. Parameters, rules and relationships related to the various material types and properties can be integrated into Computational Design (CD) models. In those models, parameters are expressed with variable properties, which relate to each other by predefined rules. Problem-solving in the design process must reckon with both ill-defined and well-defined problems (Reitman, 1964; Cross, 1984, 2000; Coyne, 2005; Casakin, 2010). Here, well-defined problems define rational processes for specific goals unlike ill-defined problems, which involve uncertainty (Suwa et al. 1999). Using CD, critical parameters affecting architectural design become well-defined and can be identified at an early stage of the design process.

1- Introduction

2- Methodology

3- Results

4- Discussion and conclusion

References

Abstract

Recent intensive eco-city development in China has been accompanied by rising enthusiasm for environmental sustainability indicators. Whilst there are calls for the indicators to be standardised, and criticism of the difficulties in applying them, little effort has been made to understand their scientific rationale. This article employs a comprehensive bibliometric analysis to investigate the use of environmental indicators from the Tianjin Eco-City Key Performance Indicators by the international scientific community working on urban sustainability. The findings draw a clear picture of the place of Tianjin Eco-City’s indicators in the international scientific literature. China’s ecological problems are found to attract interest not only from domestic researchers but also researchers outside the country. The indicators are used not only for urban planning and management but also for a wide range of urban-related and non-urban-related purposes. The scientific rationale of the eleven indicators is specifically addressed, revealing a number of underlying questions about the Tianjin Eco-City indicators.

Introduction

Following the recent promotion of eco-cities, there is increasing interest among researchers and policy makers in sustainability assessment. A sustainable city can be defined by analogy with the Brundtland Commission’s definition of sustainable development (WCED, 1987) as a city that ensures that development meets the needs of the present without compromising the ability of future generations to meet their own needs. Conventionally incorporated into the triple bottom line of environmental, social and economic criteria, the substantive purpose of sustainability assessment is to provide policymakers and city planners with tools for evaluating their cities and to help them to decide what actions to take and not to take (Devuyst et al., 2001). In this context, the main functions of sustainability assessment include decision-making and decision management, target setting, advocacy, participation and consensus building (Joss et al., 2012; Parris and Kates, 2003; Pastille Consortium, 2002). The indicators can be broken down into single-unit indices (such as ecological footprint, wellbeing index, emergy) and indicator-based indices. By contrast with single-unit indices, which score the combined performances of a city, indicator-based indices provide disaggregated information and are used to track sector-level factors (Fiala, 2008).

1- Introduction

2- Africa in context: urbanization and population growth

3- Methods

4- Results

5- Discussion

References

Abstract

Africa is urbanizing at an astonishing rate. To meet many of the Sustainable Development Goals there will be a requirement for cities in sub-Saharan Africa to plan for, and manage, the rapid rise in the urban population. Green infrastructure has the potential to provide multiple ecosystem services to benefit the urban population. The general objective of this review is to consolidate research undertaken on urban green infrastructure and the associated ecosystem services in sub-Saharan African cities. The 68 reviewed papers spanned 20 countries and included 74 urban areas. However, only 38% of sub-Saharan countries had any research carried out in them. The most represented ecosystem services were regulating and provisioning, with supporting services getting the least attention. Overall there was a lack of in-depth studies on all ecosystem services, especially supporting and cultural services. Seven overarching categories of barriers and challenges to the sustainable delivery of ecosystem services emerged from the reviewed papers, namely: (i) socio-cultural values, traditions and perceptions; (ii) lack of capacity; (iii) governance, urban planning and social inequality; (iv) lack of data and/or case studies; (v) ecosystem disservices; (vi) spatial trade-offs and conflicts; (vii) climate change. These barriers we identified will need to be addressed if the future, long-term sustainable provision of ecosystem services in sub-Saharan African cities is to be assured.

Introduction

The rise in papers focussing on urban ecosystem services (ES) underscores its importance (e.g. Elmqvist et al., 2013; Ernstson & Sörlin, 2013; Luederitz et al., 2015). Moreover, the concept of ES as essential components of sustainable and resilient cities is firmly entrenched (e.g. Ahern, Cilliers, & Niemelä, 2014; Andersson et al., 2014; Steiner, 2014), despite the ecosystem ‘disservices’ (ecosystem functions that are harmful to human well-being) which can also be a feature of nature (Gómez-Baggethun & Barton, 2013; Lyytimäki & Sipilä, 2009). Increasing evidence for the impact of climate change and the effects of natural hazards on populated areas emphasize the need for better planned and re-imagined cities. The disastrous and often tragic effects of these hazards force decision-makers to search for viable strategies to mitigate such events. Several studies document the potential of green spaces to mitigate climate change effects and reduce vulnerability (Gill, Handley, Ennos, & Pauleit, 2007; Munang, Thiaw, Alverson, Liu, & Han, 2013; Ojea, 2015; Zölch, Maderspacher, Wamsler, & Pauleit, 2016). In urban areas, green spaces can provide several benefits (urban ES) that improve the quality of life in cities (Gómez-Baggethun & Barton, 2013). Some of the benefits include: temperature mitigation (Susca, Gaffin, & Dell’osso, 2011), pollution reduction (Pugh, Mackenzie, Whyatt, & Hewitt, 2012), biological carbon storage (Davies, Edmondson, Heinemeyer, Leake, & Gaston, 2011), human health and well-being (Keniger, Gaston, Irvine, & Fuller, 2013; Shanahan, Fuller, Bush, Lin, & Gaston, 2015; Tzoulas et al., 2007), good social relations (Kuo & Sullivan, 2001; Sullivan, Kuo, & De Pooter, 2004), and habitat for biodiversity (Dallimer et al., 2012; Goddard, Dougill, & Benton, 2010).

Current attempts for sustainable-focused smart community evaluation have failed to make significant advancements, and quantitative analysis for sustainable development is still a major challenge in China. In recent years, smart community evaluation (SCE) for sustainable development has attracted considerable attentions. Government decision-makers can make it easier to stimulate household sustainable consumption by conducting SCE. This paper develops a combined analytical framework that will assist in the process of multi-source data integration and uncertain reasoning of SCE. This framework is used to combine quantitative metrics and subjective judgment with evidential reasoning approach, and this frarmework can also take decision makers’ risk preferences into consideration using prospect theory. Four urban communities are evaluated by the proposed framework to demonstrate its applicability and effectiveness.

Introduction

As the rapid development of economy and the increasing growth of population, problems such as traffic jams and population density in metropolis areas, excessive consumption of non-renewable resources, deteriorating environment and many other social problems have arisen(Chen et al., 2017; Ding et al., 2017; Wang et al., 2017). In order to address these chanllenges, the concepts of “smart planet” and “smart city” have been proposed by IBM (C. et al., 2009). In 2014, the Chinese government issued an urbanization development plan, and declared that the sustainable-focused smart community construction is one of its urban development directions. On April 7th, 2015, the Ministry of Housing and Urban-Rural Development and the Ministry of Science and Technology of the People’s Republic of China jointly confirmed a total of 209 smart community pilots which are regarded as an indispensable part of sustainable city development. By the end of 2017, more than 500 cities in China had been constructing smart communities. And during the period of the13th Five-Year Plan for Economic and Social Development of the People’s Republic of China, the investment of government on smart communities will exceed 500 billion yuan. Under the effect of policies and market driven impetus, the development of smart communities is faster and faster. Along with the development of smart communities in China in recent years, there are also a series of problems hindering smart community construction. Facing realities such as different scales of investment, great diversity of participants and various phases of sustainable development, the research on construction mode of smart community and cooperation behavior of different participants are both important for smart community development(Xia et al., 2015). But smart community evaluation (SCE) plays a crucial role in ensuring the effectiveness of its implementation and development. Although the last decade has witnessed a number of results in the research on SCE, there are still many issues to be solved as the multi-source data integration and uncertain reasoning (Chilipirea et al., 2017; Ding et al., 2014; Linlin et al., 2017; Sta, 2017). SCE can allow governments to make more effective funding arrangements, increase the capability of community service and management, and promote the transition from traditional consumption to sustainable household consumption. Performance evaluation of smart community for sustainable development has been extensively studied by both academia and industry recently, due to their socio-ecological value and the associated research issues(Wang et al., 2017). In France, Toshiba Solutions Corporation has been selected as the leading contractors for a smart community project that has achieved sustainable development by employing multiple sophisticated technologies (Nobutaka et al., 2015). In Aizuwakamatsu Japan, local government is working to build smart communities for providing a high quality of life and security to residents (Tada et al., 2014). In addition, the TERE (technology, environment, resources and the economy) model provides some convenience for exploiting marine resources and construction of smart city in Qingdao, which has been developed for better management and eco-friendly development (Wang et al.) . Over the past decades, the existing research has made great contributions to the community development, such as reputation mechanism for cooperation(Wang et al., 2017; Xia et al., 2017), multidimensional smart community discovery scheme(Kim et al., 2017), and a new government affairs service platform(Lv et al., 2017). While the existing SCE methods still have some limitations, which can be summarized as: (1) It is difficult to find an adaptable methodology to solve the problems of multi-source data integration and uncertain reasoning in SCE. (2) Few works consider the risk preference of decision makers, which has a significant impact on the sustainable-focused evaluation.

1- Introduction

2- The compact city and its hegemonic character

3- Contested spaces in the compact city: discourses and discursive practices

4- Research questions and method

5- Contested meanings of urban gardening in Swiss cities

6- Conclusion

References

Abstract

Since the intensification of the search for sustainable urban planning, the ideal of the compact and green city characterized by high density, mixed land use and attractive green infrastructure, has become a desirable urban form at global scale. Urban greening, including urban gardening, has experienced a resurgence of interest. Within the frame of the compact city, the meanings, forms and functions of urban gardening have been re-evaluated for their contribution to urban sustainability, turning those spaces into a contested subject of negotiation. This qualitative study, conducted in the Swiss cities of Basle, Berne, Geneva and Zurich, investigates how the meanings of urban gardening are discursively (re)produced in political negotiation processes and how different rationalities of space produce a hegemonic order, constructing urban gardening sites as contested spaces. The findings demonstrate that urban growth strategies within the frame of the compact city, aiming at an efficient and resource-saving (re)organization of urban space, are discursively rationalizing current transformation processes. While so-called traditional forms of urban gardening are closed down, displaced to locations with less significance for urban development plans, or transformed in spatial and functional terms, new forms of urban gardening commensurate with the current ideals of urban landscapes and are emerging in the inner-city areas.

Introduction

Since the publication of the 1987 Brundtland Commission Report Our Common Future, local authorities in developed countries have increasingly embraced concepts enabling sustainable urban development. The compact city ideal has been widely advocated as key to creating livable and sustainable cities and, thus, has become a desirable urban form at global scale (Jim, 2004; Lang, 2014; Zimmermann, 2001). Green spaces in the compact city are recognized as valuable for maintaining or facilitating high quality densification of urban settlements, and the practice of greening cities, especially the upgrading of dense urban areas with greenery, has become a widespread approach within the urban sustainability agenda. Thus, urban green spaces are undergoing a re-evaluation of their contribution to urban sustainability in terms of their meaning and role within the urban tissue, re-conceptualizing their form and function in congruence with the principles of the compact city ideal. They are characterized by multifunctional land-use, providing a range of benefits, adaptive and flexible forms, and high accessibility for urbanites (Pincetl & Gearin, 2005). Within this frame, urban allotment gardens have experienced a resurgence of interest and are increasingly the object of urban sustainability policies. It is claimed that urban gardening creates social, ecological and economic benefits for the city and its residents, strongly contributing to the development and maintenance of quality of life in the city (Kingsley & Townsend, 2006; Lang, 2014; Lossau & Winter, 2011; Pothukuchi & Kaufman, 1999; Turner, 2011). However, urban green spaces, including urban allotment gardens, compete with other uses of urban space, such as housing or business, and are often perceived as a land reserve for housing constructions and other urban development projects (Eizenberg, Tappert, Thomas, & Zilans, 2016; Jim, 2004). Thus, densifying urban areas may also be related to a loss of green space or a declining per capita green space provision (Haaland & Konijnendijk van den Bosch, 2015). In order to be able to provide sufficient and high-quality green space to urban residents, local authorities are increasingly in search of new, adaptive and flexible forms of urban gardening, characterized by high accessibility and hybrid functions (Klöti, Tappert, & Drilling, 2016).

The building sector accounts for more than 40% of the global energy consumption [1]. The total energy consumption of Chinese buildings (i.e., 16 billion tons of standard coal) accounts for 20.7% of the total national end energy consumption [2]. Building energy consumption may be lowered by reducing building energy requirements and using a renewable energy system. However, owing to indoor facilities and human activity, basic heating and cooling loads must be met. The corresponding building energy consumption can be reduced by using a renewable energy system, such as a solar energy system and a heat pump system, which are the most suitable renewable energy systems for the building sector. Heat pump systems are normally driven by grid electricity. Solar energy systems can produce electricity, thermal energy for heating and cooling, and can be used with a chiller to meet building energy requirements. The solar energy systems use less grid electricity than the heat pump systems. Therefore, based on the potential energy-saving effect, a solar heating and cooling system (SHCS) represents the most desirable option for the building sector [3, 4]. An SHCS can supply cooling energy for the chiller during the summer and heat in the winter. A typical SHCS equipped with an absorption chiller is shown in Figure 1. The chiller, solar collector, and thermal energy storage (TES) are the main components of the SHCS, and each influences the performance of the other components. Adsorption chillers and absorption chillers are the two main types of chiller available on the current SHCS market. At values of 0.45 to 0.8, the coefficient of performance (COP) of absorption cooling systems is better than that (0.2 to 0.6) of adsorption systems [5–11]. Most (~70% of) chillers used in European SHCS are equipped with absorption chillers [12], and recent statistics show that the single-effect absorption chiller is a popular choice [5–8, 13]. Cabrera et al. [14] compared the cost of different types of solar collector used in office buildings and hotels in Madrid and Copenhagen, respectively. The results showed that in the case of the parabolic trough solar collectors (PTC), the energy costs for cooling are (i) similar to those of flat plate solar collectors (FPC) and (ii) lower than those of evacuated tube solar collectors (ETC) and compound parabolic solar collectors (CPC). A study of the solar cooling system in Thailand showed that the cost of the absorption chiller and solar collector represented most of the initial investment [15]. Owing to natural variations in solar irradiation, a TES is essential for controlling fluctuations in the heat transfer fluid temperature supplied to the chiller.

1. Introduction

Due to urbanization and industrialization, China has been the biggest contributor to emissions since 2007 [1]. Industry, transportation and buildings are the three main fields of energy consumption in China, and consumption in the building sector in China has occupied more than 33% of the national energy consumption [2]. Currently, the total building area in China is near 40 billion m2 , and by 2020, the total building area will reach 70 billion m2 [2]. Meanwhile, more than 90% of existing buildings are high energy consumption, thus making China’s existing building energy consumption per unit area approximately 2 times that of developed countries in same environmental conditions [3]. Building Energy Efficiency Retrofit (BEER) provides excellent opportunities to reduce energy consumption in buildings and encourages the implementations of other sustainability practices, such as environmental protection, rational resource use, and occupants’ healthcare [4]. Building Energy Efficiency Retrofit (BEER) is a process to reduce buildings’ operational energy use by applying certain approaches of the building envelope and mechanical systems improvements while keeping the buildings’ indoor environment and comfort [5]. Thus, China should accelerate the energy efficiency improvements of existing buildings. The Energy Service Companies (ESCOs) industry, a recently emergent industry, provides a market mechanism called energy performance contracting (EPC) to deliver energy efficiency projects. EPC is a financing package that includes energy savings guarantees, associated designs and installation services for energy efficiency retrofit projects [6–9]. EPC was introduced to China in 1996 in partnership with the World Bank and the Global Environment Fund. The program aims to introduce EPC, improve energy efficiency, reduce greenhouse gas emissions, and protect the environment in China. In 1998, three pilot ESCOs were created: the Beijing ESCO, the Liaoning ESCO, and the Shandong ESCO [8]. In 2004, The Energy Management Company Association (EMCA) was created to facilitate the operation of EPC and development of the ESCOs industry in China. From then on, the number of ESCOs experienced a rapid growth period. The numbers of ESCOs, investments and production have increased over all these years (Figs. 1 and 2). There has surely been a significant average annual growth rate of 34.91% in the number of ESCOs from 2004 to 2013. In this millennium, the Chinese government has established a series of policies to support the application of EPC and the development of ESCOs. Obviously, the government’s attention brings huge developmental opportunities for ESCOs. However, such a number cannot represent a healthy energy service market since there are some inevitable obstacles leading to a difficult situation for ESCOs, especially in building sector [10]. Most of the ESCOs in China remain small. According to the EMCA, the financial capacity of Chinese ESCOs is limited: 60% of the ESCOs have less than 10 million RMB of registration capital; 20% have more than 50 million RMB of registration capital; and approximately 50% of ESCOs have less than 100 employees [11]. Moreover, in China, it is difficult for small companies with little capital to obtain loans or other financial support, thereby making it difficult for ESCOs to obtain financing [12–14].