**6. Conclusions**

Taking Pingjiang road as a test bed for analysis of property rights in historical buildings, this study highlights two key findings through the application of the Coase Theorem in the conservation of historical buildings. First, the impact of property rights, that is, whether the property rights are clear or not, will affect the progress of protection work. Second, the governance model for heritage conservation, that is, different property rights of historical buildings lead to different transformation methods.

Firstly, in the case of Pingjiang Historic Block, the result of the survey showed that unclear property rights seriously hinder urban renewal. Unclear property rights will lead to unclear responsibilities and rights, and lack of responsible persons to maintain historical buildings. Unclear property rights can hinder transactions and incur higher costs. Given the unclear property rights, historical renovation projects experience difficulties in proceeding according to their plans. Gradually eliminating the unclear parts of the chaotic property rights and implementing transformation in batches are necessary. The reconstruction project can be implemented gradually according to the unique layout of historical buildings.

Secondly, urban renewal is a process of resource optimisation and reuse. The historical and artistic values of historical buildings are valuable resources to society as a whole. In the process of sustainable urban development, it is necessary to retain the artistic and historical value and the use function of traditional architecture. When property rights are clear, public buildings are protected by the government. Similarly, when property rights are private, private property owners should be responsible for the maintenance. With a regulatory role to play, the government has the obligation to protect historical buildings through designing good policy. Therefore, historical buildings with public property rights should be gradually taken over and transformed by the government. Historical buildings with private property rights should still be maintained and managed by private property owners, which is the low transaction costs option, and the government should assume the supervisory and regulatory role.

This study has its limitations. Firstly, urban renewal is a dynamic process, and the role and capacity of government or individuals are constantly evolving or even changing functions. The data listed by the author can only cover a certain period of time, and subsequent changes are excluded. Secondly, the authors attempted to obtain official data from the government, but the property rights issue is sensitive, and the government is reluctant to provide such data. In addition, we find that the data obtained from some literature differ from the actual data. Thus, the authors spent several years collecting the data on-site themselves. However, it is admitted that some deviations were observed in cases that involved oral history, but they are verified as far as possible. This condition can be regarded as both a limitation and a unique contribution of this paper. Firsthand data are closer to the truth, and they can be used to verify the governance model in this paper. Lastly, the proposed model only provides a method, but each historical building has a unique story and value in practice. As such, the protection work must be analysed on a case-by-case basis, which can be elaborated in subsequent studies.

This model, based on sound theories, successfully solved the primary problem of adaptive reuse projects and provided solutions for other old building renovation projects with disordered property rights, so that the property rights problem was no longer an obstacle to sustainable urban development but could be explored to provide the drive force. An increasing number of vacant and dilapidated old buildings have been given new

life, which is conducive to sustainable urban development from social and environmental perspectives. While reducing the impact of buildings on climate change, at the same time, the social and artistic value of buildings has also been extended.

**Author Contributions:** All authors contributed to this paper with N.G. taking the leading role. E.H.W.C. and N.G. helped design the framework. N.G. conducted the investigation, analyzed the data, and drafted the article. E.H.W.C. and E.H.K.Y. revised the article and approved the final manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was partially funded by the Research Grants Council of the Hong Kong SAR Government Project No.15200614 (grant B-Q42P), and supported by a PhD study grant of The Hong Kong Polytechnic University.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** The data presented in this study are available on request from the corresponding author. The data are not publicly available due to the subsequent studies.

**Acknowledgments:** The authors would like to thank all the experts who shared their valuable opinions on heritage conservation and contributed their experiences and views on the heritage conservation in Suzhou. In addition, the authors would like to express their gratitude to Cao Xiuan and Zhou Sijia, who helped with data collection.

**Conflicts of Interest:** The authors declare no conflict of interest.
