The Instrumentality of Public-Private Partnerships for Achieving Sustainable Development Goals

: PPP is considered a tool for Sustainable Development Goals (SDGs) by the United Nations, however its instrumentality has never been investigated by previous research. This study explores the instrumental attributes of PPP and their contributions to the SDGs by developing a theoretical model to demonstrate their relationships. A structured analytical framework is developed to re-organise SDGs, based on the WSR method. The instrumental attributes of PPP are identiﬁed and classiﬁed into six categories. Based on the ﬁndings, practical suggestions are provided for the governments to improve the instrumentality of PPP for SDGs. The results can help the governments and practitioners in the global PPP market better understand and improve the instrumentality of PPP in achieving SDGs.


Introduction
Public-Private Partnerships (PPP) is considered an effective solution for insufficient government funds, the lack of skills and experiences of the public sector in maintaining infrastructure, and risk sharing of infrastructure projects, hence it has been widely implemented in infrastructure projects all over the world [1,2].Over the past few decades, PPP has remained the dominant model in the global infrastructure market [3,4].According to the World Bank, at least 135 countries and territories around the world are using PPP for public infrastructure development and public service procurement to date [5].Furthermore, a huge global PPP market has been formed that supports infrastructure development worldwide, which is extremely important for the sustainable development of under-developed countries.
In addition, it is claimed that PPP is a tool to improve economic, social and environmental sustainability, due to its wide application in transportation, water treatment, energy, environmental protection and public health [6], as well as in frontier areas such as artificial intelligence and green manufacturing [7].In 2016, the United Nations Economic Commission for Europe (UNECE) issued the Draft Guiding Principles on Good Governance in People-First Public-Private Partnerships for the UN Sustainable Development Goals, actively advocating PPP as an important mechanism and effective tool for countries and regions to achieve sustainable development goals (SDGs).As the PPP arrangement pays more attention to fairness and efficiency, it solves the problems of government failure and market failure to a certain extent, and its potential to help achieve the SDGs has been widely recognised [8].
Nevertheless, it is undeniable that there are challenges in the existing PPP model for supplying infrastructure and public services.For instance, the ownership of infrastructure acquired by private sectors during the concession period of the PPP project forms a barrier to the entry of other participants in the market, resulting in a certain natural monopoly of the public services it provides.Similarly, the lack of contractual spirit of local government Sustainability 2022, 14, 13756 2 of 17 will damage the interests of private sectors.The two may lead to the monopoly of service supply, excessive development or improper distribution of resources, negative externalities of society or environment, the insufficient supply of basic demand, long-term debt trap of local governments, and other dilemmas contrary to sustainable development [9].The government must find an appropriate balance between attracting social capital to participate and maintaining public interests.Therefore, to overcome the existing challenges of PPP, from the perspective of global governance, it is of great significance to study the instrumental attributes of PPP in promoting sustainable development [2].
However, the instrumentality of PPP as a tool for sustainable development has not been fully studied by researchers.PPP for SDGs is still at the initial stage of concept formation and introduction and lacks systematic theoretical research, which hinders PPP from playing its instrumental value in achieving the SDGs.This study aims to shed a light on the instrumental attributes of PPP for SDGs by answering the following questions.

1.
What are the instrumental attributes of PPP associated with the UN SDGs? 2.
How do these instrumental attributes of PPP contribute to the SDGs?
The rest of the paper is structured as follows: Part II presents the theoretical background of the study, Part III explains the methodology employed, Part IV presents the results and Part V discusses those results.Finally, the findings are summarised, and the theoretical contribution of the study is clarified.

Literature Review 2.1. The Unique Characteristics of PPP 2.1.1. Value for Money
There has been a debate on "Value for Money (VfM)" in PPP projects since the inception of PPP in the UK.The implementation of PPP to the procurement and delivery of infrastructure projects by various governments stands on the belief that PPP delivers greater VfM than the traditional delivery mode [10].As the private sector demands adequate guarantees of suitable profits through the long period of financing and large investment required for PPP projects, and the public users request cost-effective public goods and services, VfM of PPP projects can affect the realisation of SDGs [11].Atmo and Duffield [12] argued that in the electricity market, VfM could shift the focus from acquiring capital resources to improving the efficiency of service delivery, i.e., improving the sustainability of investment in PPP electricity projects.In the new energy industry, Wang et al. [13] claimed that the PPP operation offered good VfM performance, which could improve the sustainable performance.In urban rail transport, Li et al. [14] discovered that the introduction of the concept of VfM could provide a basis for pre-purchase decisions for PPP projects, thus contributing to sustainable economic development.

Risk Sharing
Due to the long contract period and complex contract structure, the risks of PPP have been widely discussed by researchers.A suitable risk allocation strategy is crucial for promoting negotiations between the government and investors.Although the government can provide guarantees for investors to share risk, excessive guarantees may increase the financial burden of the government, and insufficient guarantees may reduce the confidence of the project investors [15].Reasonable risk sharing is the key to the sustainability of PPP.Concerning the advantages of risk sharing between the public and private sectors, the optimal allocation of risk is considered one of the principal factors in evaluating and creating VfM [15].

Long-Term Contract
PPP is an innovative strategy that combines the different stages, or even the wholelife-cycle stages of a project, into one contract [16].PPP is a multilateral transaction implemented over long-time horizons, with contracts serving as tools for the tangible allocation of benefits and risks, usually for 20 years or more, hence, they face various forms of uncertainty and complexity [17].For governments, the ability to respond flexibly to potentially major changes in long-term contracts is beneficial to the sustainable performance of PPP [18].In addition, for transnational public-private partnerships (TPPP), the longterm concession contract is a positive way to promote the relationship between the project country and the host country and is also helpful for future sustainable collaborations [16].

Whole-Life-Cycle Management
The life cycle philosophy is particularly crucial for PPP projects due to the integrated duties of design, finance, construction, and maintenance, which is of great importance for achieving VfM [19].In essence, governments embrace PPP because the private sector reduced whole-life cost and motivating performance offered by the strong incentives to minimise costs and improve management over a project's life cycle [20].In addition, several scholars have discovered a link between whole-life management and sustainable development.Wang et al. [21] investigated the whole-life project management approach to PPP projects in the context of various aspects of sustainability and claimed that project management at different stages all contributed to various aspects of sustainable development.Li et al. [22] pointed out that the whole-life cycle management in the public sector played a key role in achieving sustainable development.

Private Financing
Private financing is another unique feature of PPP.Private financing in PPP enables resource-constrained governments to start projects without increasing their explicit debt levels, hence, this mechanism is often regarded as a tool for governments and municipalities to start projects with the necessary funds not available [23].In addition, private financing can act as a powerful incentive [24], as well as a catalyst for effective risk transfer [25].However, some scholars believe that private financing does not seem to have the expected incentive effect, and the positive aspects of PPP do not depend on private financing [26].The role of private financing seemed to be controversial among scholars, but it is undeniable that the PPP financing model may achieve a higher level of sustainability than traditional financing methods [8].The 2030 Agenda for Sustainable Development brings the critical challenge of how private capital can support its new goals-SDGs-to the attention of finance, business and policy actors [27].McHugh [28] indicated that the successful implementation of the UN SDGs depends upon the mobilisation of funds from the private sector.Rizzello and Kabli [27] also pointed out that private financing as a financial tool can effectively support SDGs.

PPP and Sustainability
In studies combining PPP and sustainability, various expressions such as sustainability of PPP, Sustainable PPP, PPP for sustainability [29], and PPP for sustainable development [30] have emerged in recent years.Although there is no universally accepted terminology, many scholars pointed out that there is a relationship between PPP and sustainable development.Hueskes et al. [29] described PPP as a potential tool for achieving the SDGs.Bjarstig and Sandstrom [31] pointed out that through PPP, the public and private sectors can promote the SDGs.In addition, many scholars have studied the relationship between them from different dimensions such as economy, environment and society.
PPP has the potential to create social value or value for the people by incorporating social objectives beyond common market objectives [32].However, many scholars pointed out that the contribution of PPP to social sustainability has not been taken seriously.Hueskes et al. [29] pointed out that sustainability considerations currently play only a limited role, and that the social dimension of sustainability is largely ignored.The reason was the difficulties in developing measurable criteria for the social sustainability of PPP.
In addition, PPP has also been gradually introduced to solve environmental problems, such as clean energy [33].People have become aware of the advantages of PPP in environmental protection and ecological facility construction [34].
There is no clear definition between PPP and sustainability.Although some attributes of PPP are indeed relevant to sustainable development, they have not been given sufficient attention in the past [35].There is also evidence showing that sustainability is not at the core of most PPP studies [11].Very few studies have considered sustainable development as a goal of PPP.

Research Design
Grounded theory is a widely used tool to solve the problem of how to obtain and analyse information in social research [36].It can discover theories and ensure that they conform to the actual situation, so it can provide relevant predictions, explanations, interpretations and applications [37].As the research procedure is standardised and rigorous, and the theoretical discovery process is traceable and testable to a large extent, this method has strong scientific, high reliability and explanatory power.
This study adopts the research paradigm of classical grounded theory and considers dynamic adjustments.Figure 1 illustrates the core research process, which includes two main stages: data collection and data analysis.
Hueskes et al. [29] pointed out that sustainability considerations currently play only a limited role, and that the social dimension of sustainability is largely ignored.The reason was the difficulties in developing measurable criteria for the social sustainability of PPP.
In addition, PPP has also been gradually introduced to solve environmental problems, such as clean energy [33].People have become aware of the advantages of PPP in environmental protection and ecological facility construction [34].
There is no clear definition between PPP and sustainability.Although some attributes of PPP are indeed relevant to sustainable development, they have not been given sufficient attention in the past [35].There is also evidence showing that sustainability is not at the core of most PPP studies [11].Very few studies have considered sustainable development as a goal of PPP.

Research Design
Grounded theory is a widely used tool to solve the problem of how to obtain and analyse information in social research [36].It can discover theories and ensure that they conform to the actual situation, so it can provide relevant predictions, explanations, interpretations and applications [37].As the research procedure is standardised and rigorous, and the theoretical discovery process is traceable and testable to a large extent, this method has strong scientific, high reliability and explanatory power.
This study adopts the research paradigm of classical grounded theory and considers dynamic adjustments.Figure 1 illustrates the core research process, which includes two main stages: data collection and data analysis.

Data Collection
In the first round, the data collection includes field observation and interviews with selected experts.For example, frequently-occurring words such as "financing instrument", "procurement instrument", "characteristics" and "features", are categorised as "instrument attributes", that is, the core keywords that constitute the research question of this paper are identified.The authors then collect data through theoretical sampling.The goal of theoretical sampling is to provide researchers with additional data needed to fully develop the attributes of a given category [38].This sampling approach does not require any prior assumptions, nor a sampling scheme based on assumptions.The second stage of data collection is determined by the findings of the first stage, to ensure that all data collection is aimed at discovering the theoretical relationship between PPP attributes and SDGs.
In the second round, the triangulation method is used to collect data through semistructured interviews, literature analysis and literature network analysis, to avoid subjectivity.The front-line research includes in-depth visits to PPP project sites, design institutes, government departments at different levels, and private sectors with different qualifications.The on-site survey and interviewees' profiles are shown in Tables 1 and 2, respectively.Moreover, the interview survey includes personal in-depth interviews and focus group interviews, which can balance the independent thinking and mutual inspiration of the interviewees.Coding is an analytical process used to identify concepts, similarities and concept reproduction in the data [39].In this research, the improved line-by-line coding method based on grounded theory is adopted to flexibly encode the original interview data word by word, sentence by sentence and paragraph by paragraph, according to the specific situation.If the core categories do not reach theoretical saturation, the researchers continue with theoretical sampling and selective coding until saturation is reached.After the core categories reach theoretical saturation, the research moves on to the phase of theory building.In order to avoid the interference caused by different perspectives and theoretical sensitivities under the rule of a minority obeying the majority, individual independent coding rather than collective coding is adopted in this study.

Theory Building
The components of theory building are completed through theoretical coding, which provides clarity and helps researchers tell a more coherent analytical story regarding the relationships between core concepts/categories through their results [40].In this study, the implicit relationship between concepts and categories is identified through the constant comparative method.The theoretical model is established, until the consistent understanding of concepts and theoretical saturation are reached [41].Then the theoretical saturation test is carried out to test the model.If the theory is found unsaturated through theoretical coding, researchers retrace the research process, or re-conduct theoretical sampling to provide new data until theoretical saturation is reached.

Findings 4.1. The Re-Classification of SDGs
Through a small-scale interview survey, it was found that the current classification in the UN SDGs lacked clear definitions and some sub-goals were reduplicated, causing great confusion to the interviewees.Therefore, it is difficult to link SDGs to PPP attributes through interview surveys.Some scholars also pointed out that there were many problems in the UN SDGs system, such as excessive quantity, confused classification, overlapping content, and lack of direct and practical operability [42,43].To ensure the interviewees have a consistent view on SDGs, the SDGs were re-organised by using the WSR (Wuli-Shili-Renli System Approach) system method [44].
WSR is a systematic method for observing and analysing complex problems pro-posed in the early 1990s, which embodies the traditional Chinese philosophy.The core of this method is to guide people to pay attention to the coordination of three layers when dealing with complex problems: (1) regularities in objective existence (Wuli), (2) mechanism of human involvement in objective existence (Shili), (3) patterns underlying human relations and its change process (Renli) [44].The WSR method has been widely used in management science, engineering research and many other fields [45].
As a result, the 169 SDGs were regrouped into five categories: human, environmental, economic, organisation and infrastructure, as shown in Table 3.
The Renli layer includes human rights, the economy and the environment, and is related to human factors, emphasising the impact of humans on society, the economy and the environment.The organisation located at the Shili layer refers to the stakeholder groups related to PPP infrastructure projects and their construction behaviours.It emphasises the approach and efficiency of management, and covers various aspects such as institution, leadership, policy and collaboration.The infrastructure is allocated at the Wuli layer.The achievement of SDGs relies on a variety of infrastructure and there supporting operational services.This layer mainly emphasises objective laws of nature, such as engineering and science.For validation purposes, the reclassification of the SDGs was reviewed by experts to ensure it is in line with the systemic principles of the UN guiding the development of sustainable development-related indicator systems.

Theory Building
The relationship analysis of the concepts revealed the contribution of PPP to the SDGs, based on which the theoretical model was built, as shown in Figure 2. At the macro level, SDGs (F1, F2, F3) represent the ideal state of the harmonious coexistence between humans and nature advocated by the UN [2,46].At the micro level, the F4-organisation-oriented and F5-infrastructure-oriented SDGs represent the goals of the intermediate process that must be achieved in order to reach the final results.

C6--Resilience
C6-2 The ability of the project to deal with risks Risk responsiveness is the reflection of resilient PPP at the project level 83% C6-3 Infrastructure resilience Infrastructure resilience is a reflection of PPP resilience 39% C6-4 Quality private sectors Quality private sectors are an important prerequisite to achieve PPP resilience 56%

Theory Building
The relationship analysis of the concepts revealed the contribution of PPP to the SDGs, based on which the theoretical model was built, as shown in Figure 2. At the macro level, SDGs (F1, F2, F3) represent the ideal state of the harmonious coexistence between humans and nature advocated by the UN [2,46].At the micro level, the F4-organisationoriented and F5-infrastructure-oriented SDGs represent the goals of the intermediate process that must be achieved in order to reach the final results.After a continuous comparison of substantive coding results, it is found that these instrumental attributes contribute to the SDGs in different aspects.The categories C1-Inclusiveness, C2-Environmental contribution and C3-Economic contribution correspond to the macro-level of SDGs, such as economic, social (human rights) and environmental sustainability goals.Therefore, they were named as the target attributes of PPP to SDGs.All of the target attributes contribute to the macro-level of SDGs.For instance, C1-inclusiveness has a close relationship with both F1-Human at the macro-level and F4-Organisation at the micro-level of SDGs.
The categories C4-Whole-life project management, C5-Resilience, and C6-Scalability mainly contribute to the micro level of SDGs, named as management attributes.Among these three, C4-Whole-life project management is related to both the macro level (F2, F3) and micro level (F4, F5).

Discussion
The reorganisation of UN SDGs results in a framework including five categories that can help interviewees reach a consistent perception.The instrumental attributes of PPP are identified and linked to the SDGs.The theoretical model developed demonstrates how PPP can perform as an instrument to help the achievement of SDGs.

C1-Inclusiveness
At the macro level, the inclusiveness of PPP is closely related to the human-oriented SDGs.Infrastructure and public services were developed through PPP projects, including healthcare (SDG3), education (SDG4), drinking water (SDG6), modern energy (SDG7), communication (SDG9-c), to meet humans' (F1) daily needs in an affordable and accessible way.In long-term public-private partnerships, a successful PPP project must consider and deal with the direct or indirect social influence on the host country.PPP is no longer just a tool to relieve the pressure on government finances, but also a tool to improve efficiency and fairness in providing essential infrastructures.Fairness is required by the UN SDG10 to "reduce inequality within and among countries", which is discussed in multiple aspects of PPP, such as non-discriminatory treatment of public services accessible to all (including gender, age, race, sexual orientation, culture, religion, etc.), regional balance and intergenerational justice.
In order to take full advantage of PPP, the governments should establish an appropriate project selection mechanism at the early stage of PPP.However, there is no doubt that the conflict between the limited fiscal capacity and the pursuit of inclusive maximisation of public interests will inevitably limit the profitability of the private sectors.The PPP model should explore more diversified investment return mechanisms, such as impact investing, and third-party payment.At the micro level, the government and project managers should encourage social participation in PPP projects, for instance, women and children (SDG5), and most important is in line with the SDG16-6, SDG16-7 "developing transparent institutions at all levels to ensure inclusive, participatory and representative decision-making".This can not only incorporate the public values and preferences in PPP decision-making, optimise sustainable designs, and improve projects to meet specific local needs, but also play a positive role in overseeing PPP projects and enhancing public awareness of political fairness and trust [47].Once the regulation is insufficient or fails, the private sector might abuse market forces, leading to excessive pricing or insufficient supply of services.At the same time, in the long-term life cycle of PPP projects, the asymmetric dependence between government regulators and the private sector might also lead to regulatory capture, which might lead to unfairness and damage to public interests [9].

C2-Environmental Contribution
PPP has an advantage as a tool to support the achievement of environment-related SDGs (F2), as the government can rely on the professional knowledge and experience of the private sector to provide sustainable solutions for infrastructure development.In practice, the Ecology-Oriented Development (EOD) projects with PPP aiming at improving the ecological environment increase quickly in recent years, including waste incineration power generation PPP projects, and green landscape improvement PPP projects.
The governments should implement more flexible long-term performance-based pay mechanisms to encourage the private sector to identify potential opportunities that could contribute to environmental sustainability over a long-life cycle of projects.The following six aspects should be considered: (a) reduce fresh water consumption and ensure the discharge of wastewater up to the standard; (b) reduce energy consumption and improve the energy efficiency of the project, especially at the operation stage, through innovative design and means, and use clean energy wherever possible; (c) calculate and take measures to control the carbon emissions throughout the whole-life cycle of the project, and try to achieve net zero emissions; (d) ensure the discharge of waste up to the standard, and explore the potential for recycling; (e) ensure that the project site does not occupy arable land, and improve the degraded land in the project-affected areas as much as possible; (f) reduce the impact of the project on the surrounding ecological environment, and if possible, make beneficial attempts to protect biodiversity.It is worth noting that the beneficial attempts of PPP projects to promote environmental sustainability may increase costs to the private sectors to a certain extent.Therefore, the government should clarify the scope of responsibility of the private sectors through regulations and policies and give appropriate incentives.Once the environmental department of the government was independent of the economic department to set the performance goals of the PPP project, this kind of incon-gruity would lead to the failure to achieve the final goal.Hence a reasonable reward and punishment mechanism should be carefully designed at the pre-project stage.

C3-Economic Contribution
Promoting the sustainable development of the regional economy (F3) has become one of the main reasons that many countries adopt PPP.Through PPP, the economicrelated SDGs such as developing commerce, promoting trade, increasing land value, and optimising industrial layout can be realised directly or indirectly.Especially, innovation (SDG9) is generally regarded as the first driving force of economic development, and enterprises are regarded as the main body of market competition in the market economy and the backbone of scientific and technological innovation.The PPP mechanism provides a platform for innovation-driven development due to its unique organisational model of government-led, enterprise operation, and win-win cooperation.In addition, the enlarged PPP markets can create a large number of local jobs (SDG8), as well as cultivate a group of local technical talents through training or skill development programs (SDG4-4).
In order to better realise the instrumental value of PPP in supporting the SDGs, the government should properly evaluate the VfM and profitability of PPP projects.Therefore, the private sectors have sufficient incentives to continue operating projects and improve sustainable performance continuously, whilst the public can obtain satisfactory public services at less cost.However, the private sector also has the motivation to maximise profits at the expense of the government and users.The government should establish a suitable interest distribution mechanism to maintain financial capacity, otherwise it will pass on a large number of financial debts to future generations.

C4-Whole-Life Project Management
Whole-life cycle project management is one of the most important and innovative attributes that distinguish PPP from the traditional government procurement model.It coincides with the requirements of long-term goals of the governments and can contributes to both the macro and micro levels of SDGs.The whole-life design adopted by PPP can break through the barriers of disconnection between design and construction at the organisational level (F4), making it possible for the design team to cooperate and discuss with the construction and facility management teams.The goal of the design is no longer about the completion of the construction stage, but the long-term performance of the infrastructure.With more attention paid to economic performance and functionality of infrastructure, the feasibility and usability of design can be improved.For instance, the selection of environmentally friendly materials during the design process of PPP projects will help to achieve the goal of environmental sustainability.Meanwhile, it is also necessary to be aware that the expensive and excessive design may lead to an excessive government debt burden.
The government should require the private sectors to use the whole-life costing method to prepare the total contract budget and design optimisation of PPP projects, through relevant institutional arrangements and constraints.This method considers both the initial construction cost and the future operation cost, hence can achieve whole-life cost optimisation.Furthermore, the private sectors should improve their whole-life project management skills to benefit from the cost savings and rewarding mechanism at the long-term operational stage of PPP projects.

C5-Resilience
The SDGs frequently emphasise the "encourage and promote the establishment of effective public, public-private and civil society partnerships (SDG17-17)", good "cooperation" among stakeholders, as well as "build resilient infrastructure (SDG9)".The resilience of PPP can be understood as the ability to return to an original or a new good state from an unfavourable situation during the PPP life cycle [48].It is closely related to the SDGs at the micro level (F4, F5), in which strong stakeholders and their stable partnerships are important foundations for PPP projects to deal with risks and build resilient infrastructure.
Therefore, the government can take measures to improve this instrumental attribute of PPP.(a) Considering good organisational structure, team culture, certain qualifications and social reputation, especially financial strength, rich management and technology, and inter-disciplinary cooperation ability in selecting private sectors.(b) Establishing a good trust relationship with the private sectors during the project, abiding by the spirit of the contract, and establishing an effective to resolve disputes.This can help to negotiate to solve various problems in the process of PPP projects, thereby ensuring a win-win situation to a certain extent between the underlying profitability of the private sectors and the realisation of sustainable development goals.(c) Reasonable risk sharing mechanism should be established to enable PPP projects to respond quickly, effectively and amicably to natural and man-made adverse risks such as natural disasters, critical infrastructure failures, and terrorist attacks during the whole-life cycle of the PPP project, and improve the resilience of infrastructure in the face of major disasters.Once the commercial risks of the private sectors are transferred to the government, taxpayers or users, it may lead to much painful consequences.

C6-Scalability
Scalability is often overlooked in most traditional construction projects; however, the focus on the long-term goal requires PPP to consider the broadest public interests and future needs.The decision-makers must consider the coverage of the public services of the proposed PPP projects and predict the unit cost of the services at the feasibility stage to ensure the accessibility of service to a wider range of people.Nevertheless, the users also need to have enough willingness and ability to pay for services to ensure that the expanded projects have positive cash flow.Otherwise, underpriced public services will lead to problems such as excessive demand, serious pollution and improper allocation of public funds.
Therefore, to achieve more effective scalability, governments should strive to increase the population covered by the public services of PPP projects.More active exploration should be undertaken to discover the possibility of duplicating infrastructure in other regions, or even under different boundary conditions.The establishment of best practice projects is important in terms of providing duplicable models for similar infrastructure in other areas of need.In addition, governments should consider the creation of an effective knowledge-sharing platform for the whole industry chain to promote on knowledge transfer of technology, management skills, and innovation among various stakeholders.

Conclusions
This research explored the instrumentality of PPP in achieving UN SDGs by providing a systematic analytical framework for the SDGs and a structured categorisation of PPP instrumental attributes.Through theory building of the Grounded Theory, a theoretical model was developed to demonstrate the contribution of various instrumental attributes of PPP to the five categories of SDGs.According to the findings, suggestions were put forward for the governments and practitioners globally to improve the utilisation of PPP as a tool to achieve the SDGs, such as further standardising the PPP mechanism, improving whole-life project management skills, strengthening selective criteria for the private sector, and promoting knowledge sharing.The results provide a better understanding of the instrumentality of PPP to SDGs for the global practitioners and governments in the PPP market.The reclassification of the SDGs provided a more structured way to interpret the SDGs of the UN and can be applied to a wider range of research.
This study is not exclusive in nature.Future researchers are recommended to test the theoretical model by other means such as case studies.
Appendix A Table A1.Instrumental attributes of PPP by substantive coding.

Category
Original Statement (Initial Concept) Access to public services E05 This year, there are many PPP projects of garbage incineration power generation and sewage treatment, and the projects are becoming more balanced (in a wide range of fields).E12 Now the power grid covers all remote areas (accessible to everyone) E18 Basic water, electricity, heating and communication are essential for people's lives (basic services) Equity E06 We have special access for disabled groups in this project (disadvantaged groups) E09 Most workers are recruited locally and then trained, both men and women (non-discriminatory) E17 The eastern coastal areas of China have relatively developed infrastructure, while the western areas are relatively weak (geographical balance)

Affordability
E02 The NDRC has a special price department to adjust prices (pricing levels) E04 Although there have been many major projects in recent years and the treasury is much richer than it was twenty years ago, it is still tight (fiscal deficit) E14 Profit margins are already very low, you have to keep the product quality and sell it (affordable).

Social justice
E01 That area is a local root, hundreds of years old, and must not be demolished lightly (historical background) E07 The project is within the boundaries of a cultural heritage site, so there are fears of delays (site protection) E09 The project in South America is very popular with the local population, although negotiations with the government are difficult.Utilizing the expertise of the private sectors E09 Innovative establishment of a four-party interface management model for an orderly and efficient project management process (management level) E13 Everyone knows that thermal power has a negative impact on the environment, but the project has a state-of-the-art desulphurization and denitrification design (technical capability) E15 Our company specializes in supplying custom boiler equipment to domestic super large power plants (supply capacity) Table A1.Cont.

Category Original Statement (Initial Concept)
Stable partnership E04 This is the second tender, the previous enterprise was closed down because the boss was arrested (the cooperation was terminated) E09 In the beginning, the fire brigade came to inspect every week.Over time, the relationship became better and better (trust relationship).E18 Private sectors parties are often at a disadvantage in the event of a dispute with the government (dispute resolution) The ability of the project to deal with risks E05 A contingency plan and relief fund is set up specifically for possible disaster situations (emergency reserve) E08 Autumn and winter are not only cold but also windy, and no newly planted seedlings can survive without better support (active response) E16 In sustainable development projects, the government should not deliberately impose a public goods burden on the private sectors (risk sharing) Infrastructure resilience E02 Strengthening the resilience and protection of critical urban infrastructure systems to enhance comprehensive urban disaster preparedness (disaster prevention and protection) E12 The response of critical infrastructure to various extreme challenges has been taken into account (Optimisation design) E17 COVID-19 highlights that infrastructure is the material basis for the safe operation and sustainable development of cities (Infrastructure security) Quality private sectors E02 SDGs can only be achieved if there is strong financial support (financing capacity) E09 A primary school was donated to the area, building materials and workers were readily available (social responsibility) E11 This technology works perfectly with universities to solve this challenge (collaborative capacity) Whole-life cycle costing E04 Some small projects calculate the construction and operation costs separately, without considering the mutual influence (cost correlation) E12 The design integrates construction and operation to achieve the lowest overall cost (cost optimisation) E18 Overall preparation of the contract budget is conducive to achieving VfM targets based on the concept of sustainable development (overall accounting) The concept of whole-life design E04 PPP makes it possible for the design team to discuss with the construction and operation teams (design collaboration) E13 Modern design no longer ends with construction completion, but comprehensively considers the long-term performance of the project (comprehensive benefits) E16 Design solutions should be compatible with SDGs, such as using environmentally friendly materials (catering to the objectives) Long-term goals E01 Only by adapting to long-term national and regional development strategies can PPP projects be avoided halfway (strategic fit) E09 Before the commencement of the project, we have decided which awards we will enter for when it is finished and have a detailed path plan (planning before we start) E17 Intergenerational equity concept of sustainable development should be reflected in the longer life cycle of PPP (Intergenerational concept) Integrated project management E02 New policies and requirements for PPP have emerged frequently in recent years, which are sometimes difficult to grasp as a management role for government departments (management bottleneck) E08 All department managers, including those in charge of archives, have been sent to management training in rotation (general management) E09 Everything was used to obtain equipment delivered in on time (flexible management) Water conservation and wastewater treatment E06 The water is diverted to the hills and sprinkler irrigation is installed, solving the problem of watering by the sky for years (water efficiency) E09 The wastewater composition is extremely complex, with ash flushing accounting for half, which has a very high environmental impact if not treated (wastewater impact) E17 Achieving net zero impact on surface freshwater and groundwater supplies and availability where possible (water conservation strategy) E04 Hazy weather at the beginning of winter, the regulator has increased the management of engineering companies (emission standards) E13 Exhaust gases, residues and liquids are fully considered at the design stage (waste treatment) E17 The beneficial use of project waste or excess resources can be explored, PPPs provide just the right broad platform (circular economy)

Rehabilitation of degraded land
E01 There are strict restrictions on the siting of projects, which are detailed in the newly amended Land Management Law (project land) E06 The mountains are rocky and degraded, with poor hydrological conditions, none of which would have been suitable for cultivation (land conditions) E09 Before entering the site this was a bad coastal beach, far from looking as good as it does now (land restoration) Protection of biodiversity E07 Significant improvement of the surroundings after the completion of the mountain forest and the artificial lake (ecological environment) E08 More birds, fresher air, and pheasants, rabbits and squirrels (biodiversity) E09 Our factory is near the sea, and it is now beautifully built.In the evening, sea birds fly there (ecological livability) Local economic development E01 PPP projects generally directly or indirectly drive local economic development, which is also one of the reasons for project approval (promoting development).E06 Tourism can be further developed once the Eco Park is fully completed (optimisation of industry) E07 There used to be almost no houses around the project, but now there are all kinds of businesses around and trade is well developed (economic development) Promoting employment E03 Large-scale projects can also indirectly lead to employment and effectively relieve the difficulty of local employment (indirect employment) E09 Thousands of jobs available throughout the project, both temporary and permanent (employment opportunities) E15 This is a good company, they trained their own staff and asked me to come along for the learning (skills training) Profitability E01 Government should ensure that investments in PPPs provide VfM and do not result in a large fiscal debt burden (VfM) E10 Enterprises have the motivation for continuous improvement only when their interests are guaranteed (income guarantee) E18 Sustainable PPPs should allow the public to receive satisfactory public services at a lower cost of payment (public benefit) Value for Money (VfM) E01 Quantify, to the extent possible, the public benefits in terms of sustainable development for financial cost-benefit accounting (quantitative analysis) E16 Seek for the balance between the enterprise's pursuit of maximum interests and the government's pursuit of maximum public welfare (mutual benefit) E17 Public services provided through PPP bring tangible or intangible net benefits to society (increased benefits) Note: EXX stands for the original answer of the XXth respondent.The words in brackets at the end of each sentence indicate the initial concept obtained by coding that original utterance.

Figure 1 .
Figure 1.The core research process of this paper.Figure 1.The core research process of this paper.

Figure 1 .
Figure 1.The core research process of this paper.Figure 1.The core research process of this paper.

Figure 2 .
Figure 2. The theoretical model of the instrumentality of PPP to SDGs.

Figure 2 .
Figure 2. The theoretical model of the instrumentality of PPP to SDGs.
aspects are open to the public (for consultation) E09 Start to learn the local culture as soon as you arrive and try to get on well with the local chiefs (integration) E12 Design front-loading is a highlight, with all parties approached for input at the survey stage (advance participation) Fraction of coverage E04 PPP projects are all expensive, so it is important to enhance the beneficiary population as much as possible (a wide range of beneficiaries) E13 Design with a sense of foresight, especially PPP, anticipating what might happen in ten or twenty years (future demand) E18 In addition to meeting the final design function, it should also shine through the longer construction and operation process (extended impact) Replicability E03 The city should take the lead and organise all districts to learn from the success of this project (experience promotion) E04 The main design idea remains the same, with minor modifications to suit the actual situation (design convenience) E10 Multiple original bidding sections are invited for bidding together, which can save costs with large scale (scale effect) Technology Transfer and Innovation E09 Develop intelligent information management technology to provide powerful project management and decision support (management innovation) E11 Through the high-quality platform of the project, a number of advanced technical standards and patents have been formed (technology upgrades) E16 It should also facilitate the flow of technical knowledge and innovation among stakeholders (effective sharing)

Table 1 .
The organisations for site survey and interview.

Table 2 .
The profile of interviewees.

Table 3 .
The coding and classification of SDGs.
Note: For the numbering of goals, see the UN "Global Indicator Framework for the SDGs and Targets of the 2030 Agenda for Sustainable Development".4.2.The Instrumental Attributes of PPPAt the open coding stage, more than 630 original statements and corresponding initial concepts are obtained.The repetitive core concepts are selected as the instrumental attributes of PPP, as shown in Appendix A.By selective coding, six core categories are identified, including 27 corresponding open coding categories.The attention frequencies are shown in Table4.The top 2 most critical instrumental attributes of PPP for SDGs were C4-2 The concept of whole-life design (100%) and C6-1 Stable partnership (89%).

Table 4 .
Core categories formed by selective coding.

Table A1 .
Cont.Energy efficiency E01 Our city is negotiating the introduction of a clean energy heating PPP project (clean energy) E12 Increasing the energy conversion efficiency of thermal power plants means increasing business efficiency (improving energy efficiency) E18 Energy consumption in the operational phase is often not appreciated, but the waste over time is huge (energy reduction)Low carbon emission E05The State Council hosted a meeting on supporting climate change and Low-carbon Development through PPP (emphasis on carbon reduction) E11 Planting trees in the park to absorb CO2 equivalent emissions (net zero emissions) E17 PPP whole-life cycle GHG emissions can be calculated (calculation of emissions)