Research Hotspots and Trends in Green and Low-Carbon Building Retrofits in the Context of Urban Renewal

Qu Rong, Ye Jiahong, Zhang Xue

Citation Format: Qu Rong, Ye Jiahong, Zhang Xue. Research Hotspots and Trends in Green and Low-Carbon Building Retrofits in the Context of Urban Renewal [J]. Green Building, 2024, 16(6): 69-77.

 

Abstract:

As the world's largest energy consumer and carbon dioxide (CO ₂ ) emitter, China's building sector accounts for 51.3% of the country's total carbon emissions. As China's urban development gradually shifts from incremental expansion to stock renewal, green and low-carbon building retrofits in the context of urban renewal are crucial for helping China achieve its "dual carbon" goals. In recent years, research in the field of green and low-carbon building renewal has gradually increased, but a systematic review and analysis of relevant research findings are still lacking. Based on this, through

Keywords:

Urban Renewal; Building Retrofits; Green Buildings; Energy Saving and Carbon Reduction; Intelligent Algorithms

0 Introduction

 

Climate change is considered one of the most serious threats facing human society today, and this global challenge is increasingly attracting widespread international attention. ^[1-2] Excessive energy consumption leads to increased greenhouse gas emissions, thus exacerbating the severity of the climate crisis. Therefore, a green, low-carbon, and sustainable development model has become a global consensus, with countries actively working to reduce carbon emissions through policy and technological means to address the challenges posed by climate change. ^[3] As the world's largest energy consumer and CO ₂  emitter, China bears a significant responsibility in addressing climate change. Existing research shows that in 2020, China's energy consumption accounted for approximately 26.13% of global primary energy consumption. ^[4] Against this backdrop, the Chinese government has clearly put forward the "dual carbon" goals of achieving "carbon peaking" before 2030 and "carbon neutrality" before 2060. To achieve this goal, in-depth structural adjustments and green transformations are necessary across all sectors. The energy consumption of the building industry accounts for about 30% of the total social energy consumption, and building carbon emissions account for 51.3% of the total social carbon emissions. ^[5-6] Based on this, China has issued documents such as the "14th Five-Year Plan for Energy Conservation and Green Building Development" and the "Work Plan to Accelerate Energy Conservation and Carbon Reduction in the Building Sector." In addition, with the acceleration of China's urbanization process, urban development is gradually shifting from incremental expansion to stock renewal. Therefore, promoting green and low-carbon building retrofits is one of the key links in helping China achieve its "dual carbon" goals.

In recent years, research in the field of green and low-carbon building renewal has developed rapidly, achieving significant results, but these results still lack systematic review and analysis. The authors use CiteSpace software to conduct a quantitative analysis of relevant domestic and foreign literature, summarizing current research results on green and low-carbon building retrofits and clarifying their development trajectory to further explore research hotspots and trends in green and low-carbon building retrofits in the context of urban renewal.

1 Data Source and Analysis Methods

 

1.1 Data Source

The data for this study comes from the China National Knowledge Infrastructure (CNKI) database and the Web of Science (WOS) core collection database. In the CNKI database, the author used "building retrofitting" and "green" as keywords, with no time limit and a search scope limited to academic journals in the field of architecture and engineering, obtaining a total of 1,286 relevant journal articles. In the WOS core collection database, the author used "building retrofitting" and "green" as keywords with no time limit, obtaining a total of 635 relevant articles. These articles cover various research results on green buildings and building retrofits, providing abundant theoretical and practical references for green and low-carbon building retrofits. The analysis of foreign literature further provides an international perspective for the analysis of this research topic, making the exploration of research hotspots and trends more comprehensive.

1.2 Data Processing and Analysis Methods

The author used a combination of qualitative and quantitative analysis methods to systematically review and conduct in-depth research on domestic and foreign literature on the topic of "green and low-carbon building retrofits." Data processing first involved using CiteSpace software to conduct visual analysis of the acquired literature data, identifying high-frequency keywords through keyword co-occurrence analysis to reveal the core research topics and hotspots in the field of green and low-carbon building retrofits; cluster analysis was used to discover the aggregation characteristics of different research topics, revealing the main directions and fields of relevant research. In addition, the author conducted a detailed analysis of the information on the authors and institutions of the selected literature, identifying the main researchers and research institutions in this field and understanding the research cooperation networks and influence of various researchers and universities.

Based on the visualization results of CiteSpace, the comparative inductive method and literature review method were further used to conduct in-depth analysis of the acquired literature data. ^[7] The comparative inductive method allows for a systematic comparison of the similarities and differences between domestic and foreign research in the field of green and low-carbon building retrofits, revealing the research characteristics and development trends under different cultural backgrounds and research environments; the literature review method is used to integrate existing research results to further explore potential future research directions and key issues.

2 Research Data Analysis

 

2.1 Publication Trend Analysis

The author conducted a statistical analysis of the annual publication volume of 1,381 Chinese and 634 English articles from 2008 to 2024, with the results shown in Figure 1.

Figure 1 shows that the number of publications on the topic of "building retrofitting" and "green" in both Chinese and English journals shows a year-on-year upward trend. In addition, Chinese scholars are more active in this research field and produce more research results.

Analysis of the CNKI database shows that since 2016, over 100 related articles have been published annually. The year with the highest number of publications is 2023, with 142 related articles. As of July 2024, 135 related Chinese research findings have been published in 2024. Based on this publication trend, it is expected that the number of Chinese articles on "green and low-carbon building renovation" published in 2024 will reach a new high. This trend is also in line with the "urban renewal action" clearly proposed in the "Suggestions of the Central Committee of the Communist Party of China on Formulating the 14th Five-Year Plan for National Economic and Social Development and the Long-Range Objectives Through the Year 2035". ^[8] This emphasizes that the focus of future urban construction will shift from incremental to stock, with renewal replacing new construction. This also reflects the role of national policies in promoting academic research development.

The publication trend of related English literature in the WOS database shows that since 2018, research on green building renovation has significantly increased, reaching its peak in 2023 with 95 articles. This shows that in the international academic community, research on green building renovation has also become a hot topic in recent years.

In summary, the research focus in both Chinese and English-language fields has gradually shifted towards renovation projects in recent years, especially the research on green and low-carbon building renovation. Driven by policy and academic attention, the research enthusiasm in this field is expected to remain high, and more innovative research findings may emerge in the future, further promoting the green transformation and sustainable development of the construction industry.

2.2 Author Analysis

The authors of 1,381 Chinese articles and 634 English articles published between 2000 and 2024 were analyzed to identify the main researchers in the field of green and low-carbon building renovation and their collaborative networks.

The author collaboration network diagram for related literature in the CNKI database is shown in Figure 2.

Figure 2 shows that from 2010 to 2015, the main researchers in the field of green and low-carbon building renovation included Wang Qingqin, Ye Ling, Cheng Zhijun, and Wang Jun, etc. ^[9-12] During this period, these scholars formed a close collaborative network through frequent collaborations and joint publications, laying a solid research foundation for the field. From 2015 to 2020, the composition of researchers changed somewhat. Researchers such as Ye Ling and Wang Qingqin remained active in this field ^[13] . Their continued research and collaboration further deepened the understanding of green and low-carbon building renovation, pushing the field forward. Meanwhile, Feng Xiaotong, Wang Qiqing, Li Minghui, etc. ^[14-15] also conducted in-depth explorations on this topic during this period. From 2020 to the present, scholars such as Guo Handing, Jin Zhenxing, and He Yutong have become the main force in this stage ^[16] . Their research not only promoted the further development of the field but also formed a new academic network through mutual cooperation, significantly enhancing the breadth and depth of the research.

The author collaboration network diagram for related literature in the WOS database is shown in Figure 3.

Figure 3 shows that this network mainly formed after 2015. The collaboration network before 2015 was relatively sparse, with only a collaborative group composed of scholars such as Nicknam, Eslamian, and Bozorgnasab. However, from 2015 to 2020, the collaboration network gradually expanded and formed several main groups. These include the collaborative team represented by Yue Tao and Zuo Penglai, the collaborative group of Fernot, Niculita-Hirzel, Licina, etc., and the collaboration network of Bazzocchi and Banti, etc. In recent years, especially in the past one or two years, the main scholars conducting research on this topic have gradually become Yang, Sun, Li, and Liu, etc. This phenomenon indicates that Chinese researchers are gradually expanding their research in the English-language field. Their activity in international journals has not only enhanced the influence of Chinese scholars in this field but has also promoted academic exchange and cooperation worldwide. This trend shows that China's strength in related research fields is constantly increasing, and research findings are being widely recognized by the international academic community. In the future, as more Chinese scholars participate in international cooperation and publish English papers, research in this field will have a significant impact on the global academic community.

In summary, from 2010 to the present, the researcher network in the field of green and low-carbon building renovation has not only continued to grow but also its collaborative relationships have become increasingly complex and close. This dynamic change reflects the evolution of the research frontier and hotspots in this field over time, and it also shows the synergistic effect among different researchers and their contribution to the development of the field.

2.3 Institutional Analysis

A visualization analysis of the publication institution data in the field of green and low-carbon building renovation from the CNKI database is shown in Figure 4.

Figure 4 shows that several universities and research centers, such as Xi'an University of Architecture and Technology, China Academy of Building Research, and Tianjin University, have abundant academic achievements in this field and maintain a certain level of academic activity. From a time dimension perspective, Xi'an University of Architecture and Technology, China Academy of Building Research, and Shandong University have shown a high degree of continuity in their research in this field, indicating that these institutions have continuously invested a large amount of resources and energy in green and low-carbon building renovation, maintaining long-term research focus and stable output. In recent years, Tianjin Chengjian University's Ecological and Livable City and Sustainable Building Management Research Center and Nanchang University have shown significant research activity in the field of green and low-carbon building renovation. The addition of these emerging institutions has not only injected new research strength into this field but has also promoted the further development of related research. In addition, there is close interaction between China Academy of Building Research and Shenyang Jianzhu University, Chongqing University, and Beijing University of Civil Engineering and Architecture in the field of green and low-carbon building renovation, indicating that there are obvious academic collaborations among the above-mentioned institutions. These collaborations have not only promoted the exchange of knowledge and technology but have also helped to promote the implementation of cross-institutional research projects, improving the quality and impact of research findings.

The publication institution data in the field of green and low-carbon building renovation from the WOS database is shown in Figure 5.

Figure 5 shows that Tongji University, Tsinghua University, and the Hong Kong Polytechnic University, among other universities in China, have demonstrated high influence and activity in international academia in this field. In terms of active time points, research on this topic by Chinese universities has mainly concentrated since 2020. Before that, foreign universities and laboratories such as the University of California, Berkeley, Lawrence Berkeley National Laboratory, and North Carolina State University were the main players internationally. From the perspective of temporal continuity, the Hong Kong Polytechnic University, Tongji University, and Xi'an University of Architecture and Technology have shown relatively sustained and far-reaching academic output in the field of green and low-carbon building renovation. These universities not only have a significant number of research achievements but also maintain a high academic standard in terms of quality, indicating their long-term investment and research enthusiasm in this field. In addition, Figure 5 also reveals the cooperative relationships between various universities and research institutions. There is a clear cooperative relationship between the Hong Kong Polytechnic University and Tongji University, and Chongqing University also has close interactions with many other domestic and foreign universities and research institutions. In addition to major research institutions in China, internationally renowned universities and research centers such as MIT, Harvard University, and UCL have also conducted in-depth explorations in this field. These international institutions have varying degrees of cooperation with major research institutions in China, indicating that the research in this field has highly international and transnational collaborative characteristics.

Overall, Figures 4 and 5 comprehensively reflect the research landscape in the field of building science and technology at home and abroad, showcasing the research output, cooperative relationships, and influence of major academic institutions. This not only helps identify key influential research institutions and scholars in this field but also provides valuable references for future research cooperation, resource allocation, and policy formulation.

3. Research Hotspots and Development Trends

 

3.1 Research Hotspots

Based on CiteSpace, the author conducted a keyword co-occurrence analysis of 1,381 research papers on "green building renovation" in the CNKI database, with the results shown in Figure 6. The size of the nodes in the figure represents the frequency of keywords in the literature; the larger the node, the higher the frequency of the keyword. This shows that keywords such as "green renovation," "energy-saving renovation," "green energy saving," and "green technology" are research hotspots in this field. In addition, the color of the nodes delves into the appearance time and duration of each research hotspot. Figure 6 shows that the research hotspots of "green building" and "energy-saving renovation" emerged as early as 2005 and have continued to the present. In recent years, research hotspots have gradually focused on directions such as "building energy consumption," "renovation strategies," and "low carbon." This shift in research focus is consistent with China's recent "dual carbon" strategy and the need for energy saving and emission reduction. Specifically, research on "green building" and "energy-saving renovation" in the early stages mainly focused on the discussion of basic theories and technical methods, while with the passage of time, the focus of research has gradually shifted to practical applications and comprehensive strategies. ^[17-18] and also explores methods of energy consumption monitoring and management ^[19] ; "renovation strategies" involve how to improve the overall energy efficiency of buildings through scientific design planning and the implementation of effective renovation schemes ^[20] ; and "low carbon" focuses more on achieving sustainable development of the building industry and reducing carbon emissions through technological innovation and policy guidance ^[21] 。

The author conducted a keyword co-occurrence analysis of relevant research literature in the WOS database, with the results shown in Figure 7.

Figure 7 does not show any obvious core research hotspots; the keyword distribution is relatively uniform, mainly focusing on areas such as "performance," "energy efficiency," and "simulation." From the research time point of view, most of the research hotspots in the WOS database appeared after 2015, such as "multiobjective optimization," "energy saving," and "strategy." Among them, "energy saving" and "strategy" are consistent with the recent hotspots in the CNKI database, indicating that recent building renovation research has focused on the energy-saving field and the selection of renovation strategies. In addition, foreign literature also mentions the keyword "multiobjective optimization," indicating that in the field of green building renovation, researchers are beginning to focus on how to balance multiple objectives, such as cost, energy efficiency, and environmental impact ^[22] . This method can provide more comprehensive solutions that meet the complex needs of modern building renovation.

Through the analysis of the keyword co-occurrence networks of relevant domestic and foreign research, it is not difficult to find that in the field of green building renovation, the research focus has gradually shifted from theory and methods to practical applications, comprehensive strategy selection, and multi-objective optimization.

3.2 Research Trends

Through keyword clustering and evolution analysis of relevant literature in the CNKI database, the author found that Chinese research on the topic of "green building renovation" can be roughly divided into 13 categories, including "green renovation," "energy-saving renovation," and "evaluation system," as shown in Figure 8. Further analysis of the formation time points of different clusters reveals that "green building renovation" and "energy-saving renovation" are hotspots formed after the "evaluation system," indicating that the development of green building renovation largely depends on the maturity and improvement of the evaluation system ^[23] . This is because the formation of the evaluation system provides standards and frameworks for green building renovation, giving relevant research a clear direction and goals. The evaluation system is not only a tool for measuring the effects of renovation but also an important basis for guiding the formulation of renovation strategies. In addition, this evolutionary trajectory also shows that the focus of building renovation research has gradually shifted from theoretical exploration to practical application since 2016.

Figure 8 shows that in the years after the formation of the "evaluation system," research on "green renovation" and "energy-saving renovation" grew rapidly and began to focus on ecological strategies, intelligent design, and renovation benefits, further improving the scientific nature of building design and renovation ^[24-26] . In addition, the research hotspot of "renovation strategies" has received widespread attention around 2020. In recent years, most of the research in this field has revolved around research-based reviews, focusing on public participation in renovation design, evolutionary game theory, and specific renovation design research frameworks. It is evident that public participation plays a crucial role in building renovation ^[27] . Renovation design must not only meet technical standards and energy-saving requirements but also meet the actual needs and expectations of the public. Especially in residential area renovation, the resettlement of residents becomes a key factor. Ensuring that the renovation plan is understood and supported by residents helps reduce resistance during project implementation and improve the smoothness and satisfaction of the renovation. In addition, it is worth noting that evolutionary game theory has been widely used in the research of renovation strategies ^[28] It is a method that combines game theory and evolutionary biology, emphasizing the dynamic changes and adaptability of individual strategies. It is suitable for balancing and resolving the conflicting interests of various parties in the transformation process, providing the possibility of a comprehensive optimal solution for targets such as energy saving and transformation costs. Finally, the specific design of the transformation research framework has become one of the recent hot topics, reflecting the academic community's high attention to this field, as well as the actual transformation needs and policy's strong promotion of green and low-carbon transformation in the current stage of urban development.

From the keyword clustering and evolution in the WOS database, the main research in this field can be divided into 9 categories, including "energy efficiency", "machine learning", "genetic algorithm", "carbon sequestration", etc., as shown in Figure 9.

Unlike the clustering results of the CNKI database, some algorithms appeared in the relevant type classification of WOS. This shows that during the same period, in the foreign research on green and low-carbon building transformation, scholars have begun to pay attention to the cross-possible between cutting-edge algorithms and buildings, striving to simplify building performance assessment in the transformation process through machine learning. ^[29] This is because machine learning technology can handle a large amount of building data and train models to quickly assess building performance, including energy consumption prediction, and pre-evaluation of indoor and outdoor wind, light, and thermal environmental quality. ^[30] In addition, generative algorithms are also a research hotspot in recent foreign literature. ^[31] It generates building design schemes based on computer algorithms. By setting corresponding design goals and constraints, it automatically generates and optimizes schemes. Unlike traditional manual design, generative design algorithms can explore a large number of design schemes and select the optimal solution to further improve design efficiency and quality. This design process is usually combined with parametric design and optimization algorithms.

From the evolution of clustered keywords, it can be further found that machine learning is usually related to building performance, multi-objective optimization, and keywords such as carbon emissions and carbon neutrality. This also reflects the important trend of this research direction in the foreign field, specifically including the following 3 points.

(1) Building performance and energy efficiency improvement. Through machine learning models, predict the energy consumption trend of buildings and formulate energy efficiency optimization strategies. At the same time, monitor and manage building energy consumption in real time, reduce energy waste, and improve overall energy efficiency.

(2) Comprehensive consideration of multiple design objectives. Consider multiple design objectives and constraints simultaneously to achieve global optimization of design schemes and help designers make optimal design decisions.

(3) Building energy saving and carbon reduction. Optimize building performance by transforming and maintaining structures, HVAC systems, lighting systems, etc., to further reduce building energy consumption. In addition, the transformation also focuses on carbon sequestration measures such as rooftop greening to further achieve carbon reduction.

By comprehensively comparing the keyword clustering and evolution results of the CNKI and WOS databases, it can be found that the research on green and low-carbon building transformation in the Chinese field is still in its early stages in the field of intelligence, which is a hot direction for future in-depth exploration. In addition, building transformation focuses on building energy consumption factors both domestically and internationally, indicating that energy saving and emission reduction has become the general trend of global urban renewal. Through this comprehensive analysis, we can better understand the current situation and future development trend of green building transformation, providing strong support and reference for relevant research and practice.

4 Conclusion

 

Based on CiteSpace, this paper conducts a visual analysis of relevant research on topics such as "green" and "building transformation" in the CNKI and WOS databases. Based on the analysis results, the following conclusions are drawn.

(1) Green and low-carbon building transformation is a current research hotspot in existing cities. With the acceleration of urbanization and the popularization of the concept of sustainable development, green building transformation has become an important issue in the construction of existing cities. In addition, a series of relevant policy documents issued by China, such as the "14th Five-Year Plan for Building Energy Saving and Green Building Development" and the "Notice on Further Doing a Good Job in the Preservation, Utilization and Renewal and Transformation of Existing Urban Buildings", indicate that green and low-carbon building transformation is the general trend of the future building industry.

(2) Necessity of interdisciplinary cross-research. Although Chinese scholars started to pay attention to the field of green and low-carbon building transformation earlier, in international research, the disciplinary vision of foreign literature is broader, covering more advanced technologies and methods such as parametric design, machine learning, and multi-objective optimization, providing new ideas and tools for building low-carbon transformation.

(3) Possibility of international cooperation in low-carbon transformation. Internationally, Chinese universities and scholars are gradually emerging in the research on green and low-carbon building transformation. Current global climate change is a common challenge faced by all countries. Through international cooperation, technology sharing and innovation can be achieved. For example, combining China's rich experience in building energy-saving technology with foreign leading advantages in intelligent buildings and advanced algorithms will promote the comprehensive application and innovation of technology.

5 Concluding remarks

 

Against the background of current urban renewal, green and low-carbon building transformation has become an important development direction for the building industry. This paper presents the research hotspots and trends of green building transformation worldwide through visual analysis of relevant literature in the CNKI and WOS databases. Data analysis reveals that although Chinese scholars have laid a solid foundation for future in-depth research through more than ten years of cultivation in this field, there is still much room for improvement in the application of intelligent cutting-edge algorithms compared with international research. Therefore, future green and low-carbon building transformation will combine intelligent technology and cutting-edge algorithms to further achieve a comprehensive improvement in building performance and energy efficiency optimization. In addition, international cooperation will provide a broader platform for technology sharing and innovation, promoting the development of global green building transformation and contributing to the achievement of the "carbon neutrality" goal and sustainable urban construction.

 

References:

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[2] SI F Y, DU E S, ZHANG N, et al. China’s urban energy system transition towards carbon neutrality: Challenges and experience of Beijing and Suzhou [J]. Renewable and Sustainable Energy Reviews, 2023(183): 113468.

[3] SATOLA D, WIBERG A H, SINGH M, et al. Comparative review of international approaches to net-zero buildings: Knowledge-sharing initiative to develop design strategies for greenhouse gas emissions reduction [J]. Energy for Sustainable Development, 2022(71): 291-306.

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Funding Project:

Sub-topic of the 14th Five-Year National Key Research and Development Program: "Integrated Design Technology Framework for In-situ Construction and Precast Assembled Building 3D Printing Scene Fusion" (2023YFC3806905)

Author Introduction:

First Author:

Qū Rong, a master's degree graduate and engineer, whose research focuses on healthy and sustainable building design, currently works for China Construction Science and Industry Group Co., Ltd.

Corresponding author:

Zhang Xue, an undergraduate and engineer, whose research focuses on low-carbon buildings and building industrialization, currently works for China Construction Science and Industry Group Co., Ltd.