From Fragmentation to Collective Action: A System Dynamics–Based Approach to Addressing Stakeholder Engagement in the Building Sector’s Circular Economy Transition^†

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article addresses the topic of the transition towards a circular economy in the construction sector by employing a complex system dynamic-based modeling approach to visualize, explore, and evaluate stakeholders relationship. The article investigates the interdependencies and feedback mechanisms that drive decision-making, offering an interesting contribution to the construction sector. The topic is therefore of interest for research in the construction sector and provides continuity with previously published research on the topic by the same author.

The organization of the article is appropriate; the introductory section clearly presents the scope of the research, while the methodological chapter details the approach used. The use of references in the literature review section is sufficient to provide a detailed overview of the state of the art. The results and discussions are consistent with the article's objective.

However, before publication, the following minor revisions are recommended:

• If possible, revise the title by removing the "dynamic" repetition
• "Literature review" section; it might be more appropriate to say just: "Complex System Science Simulation Methodological Tools"? If you cite a literature review, I expect to know the methods and materials with which you conducted it.
• Methodology. Better explain the limitations of the methodological approach used. What does this passage (line 261) mean: "the model has not been formulated and thus has not been performed either by itself or with different scenarios due to the presence of many quantitative and qualitative data simultaneously without any correlations as equations determining the relationships among variables"? How does this affect the research results?
• Chapter 4. When discussing the "Real Circular Building Scenario", I would have used variables explicitly related to the circular model (e.g., 9R-strategies). In this case, the variables seem more like objectives, and therefore actions such as refusing, rethinking or remanufacturing, etc., are missing. Perhaps it would be useful to clarify this passage with a sentence.
• Chapter 4. It is not clear how the 11 circular building examples were analyzed. If they led to the subsequent considerations, it would be useful to mention this more explicitly, perhaps by citing the individual case in the discussion.
• Conclusions. Although the fragmentation aspect clearly emerged in the discussion of the results, the transition to a "collective action" requires further elaboration. As this is a key aspect of the article, it would be useful to better explain how the use of the systemic model advises and promotes collective action.
• General. The images, especially the full-screen ones, are of low quality and do not facilitate reading.

Author Response

1# Reviewer 
Revision 1: If possible, revise the title by removing the “dynamic” repetition. 
Response 1: The title has been revised per the reviewer’s comments. It can be found in line 3. 
Revision 2: “Literature review” section; it might be more appropriate to say just: “Complex System 
Science Simulation Methodological Tools”? If you cite a literature review, I expect to know the methods 
and materials with which you conducted it.
Response 2: It has been changed to the “state of the art”, which can be found in line 114.
Revision 3: Methodology. Better explain the limitations of the methodological approach used. What 
does this passage (line 261) mean: “the model has not been formulated and thus has not been performed 
either by itself or with different scenarios due to the presence of many quantitative and qualitative data 
simultaneously without any correlations as equations determining the relationships among variables”? 
How does this affect the research results?
Response 3: The methodology section has been revised per the reviewer’s comments. It can be found 
in lines 207-285, specifically 270-285.
Revision 4: Chapter 4. When discussing the “Real Circular Building Scenario”, I would have used 
variables explicitly related to the circular model (e.g., 9R-strategies). In this case, the variables seem 
more like objectives, and therefore actions such as refusing, rethinking or remanufacturing, etc., are 
missing. Perhaps it would be useful to clarify this passage with a sentence.
Response 4: The methodology section has been revised per the reviewer’s comments. It can be found 
in lines 253-269. Also, the results and discussion section has been revised, which can be found in 623-
629, 644-651, and 668-672.
Revision 5: Chapter 4. It is not clear how the 11 circular building examples were analyzed. If they led 
to the subsequent considerations, it would be useful to mention this more explicitly, perhaps by citing 
the individual case in the discussion.
Response 5: The methodology section has been revised per the reviewer’s comments. It can be found 
in lines 253-269. Also, the results and discussion section has been revised, which can be found in 623-
629, 644-651, and 668-672.
Revision 6: Conclusions. Although the fragmentation aspect clearly emerged in the discussion of the 
results, the transition to a “collective action” requires further elaboration. As this is a key aspect of the 
article, it would be useful to better explain how the use of the systemic model advises and promotes 
collective action.
Response 6: The conclusions section has been revised per the reviewer’s comments. It can be found in 
lines 860-926.
Revision 7: General. The images, especially the full-screen ones, are of low quality and do not facilitate 
reading.
Response 7: The images’ quality has been improved, as found in the revised manuscript. 
• Revisions performed according to the other reviewers have been highlighted in yellow and can 
be found in the revised manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Thank you for the opportunity to review your manuscript. The article takes up an important issue and has significant potential but requires some work. 

In general
1.    The author emphasizes that the article stems from a PhD thesis. In this context, it is noteworthy that the supervisor is not listed as a co-author, which is uncommon in academic practice, where supervisors are frequently included as co-authors of publications derived from doctoral research.

Abstract
2.    Abstract exceeds the 200 words limit
3.    Incomplete mention of the methodology used, leaving out important information about the study's approach.
4.    Limited discussion of the significance or potential implications of the findings, missing the opportunity to highlight the practical importance of the study.

1. Introduction
5.    The novelty and contribution of the paper should be highlighted
6.    It is strongly recommended mentioning the relationship of the paper with previous publication of the author
7.    The statement presented in lines 82–83 relies solely on self-citation and may be reinforced by supporting evidence from other authors.

2. Literature Review
ok

3. Methodology
8.    Lack of clarity in explaining the steps of the data analysis, making it difficult for readers to follow the research methodology.
9.    Missing details or explanations about certain aspects of the analysis
10.    Insufficient details about the methodology used for data collection and analysis may affect the study's transparency and reproducibility.
11.    Regarding the problem identification stage, the author states that “this stage was not directly performed in this article, as it was built upon the authors’ previous publication [23]” [246–247]. It is strongly recommended that the scope and contributions of each publication be clearly delineated. Furthermore, it is generally considered inadequate to establish the core of a journal article based primarily on a conference paper, given that such papers typically do not undergo the same rigorous peer-review process as journal publications. Consequently, conference papers should be regarded as provisional outputs of ongoing research.
12.    Further clarification is requested regarding the statement in lines 261–264 that “the model has not been formulated.” 
13.    The study derives its variables from prior international literature but does not clarify whether these are suitable for application in any specific national context. Beyond establishing relevance, the manuscript should address whether the selected variables are contextually appropriate. It remains unclear whether they are sufficiently comprehensive and representative for diverse settings, such as Asian countries like China, or if they primarily reflect conditions typical of European contexts. Additionally, the study does not indicate any attempt to investigate the inclusion of locally specific variables or the removal of potentially irrelevant ones to enhance contextual fit.
14.    The manuscript claims to integrate real-world circular building case studies into the model to demonstrate the feasibility of system-wide transformation. However, the methodology behind this integration remains unclear. It is important to specify what data were extracted from the base articles, how these data were collected, and in what manner they were organized and systematized for incorporation into the model.
15.    Since primary data was not collected at any time, how was the model validated?

4. Results and Discussion
16.    Further clarification is requested regarding the inclusion of “Environmental Impact Generation” and “Circular Economy Strategies” in the “Final System Dynamics Model Construction”. Specifically, it would be helpful to explain whether this refers to a methodological limitation, a future development step, or an intentional choice within the research design.
17.    The section lacks a clear synthesis of the main findings, making it challenging to identify the key takeaways from the results
18.    Failing to compare findings with existing research in the field limits the context and significance of the study.
19.    The implications of the study are not enough. 

5. Conclusion
20.    It has redundant passages that make the text confusing.
21.    The content of the conclusion section aligns more closely with what is typically expected in a discussion section. It is therefore recommended that a new subsection, titled 4.3 “Discussion,” be inserted before the conclusion. A substantial portion of the current conclusion text should be relocated to this new subsection to ensure structural clarity and to maintain the distinct purpose of each section. Specifically, the content between lines 830–856, along with Table 2, should be reviewed to assess its pertinence within the conclusion section.
22.    The origin of the practical recommendations presented in Table 2 is unclear. It should be specified whether these recommendations are original contributions from the authors or if they were derived from existing literature. It would be interesting to submit it to experts to validate the recommendations or to add new recommendations.
23.    Still on table 2. A feasibility discussion of practical recommendations is still needed. Specifically, the paper presents 47 practical recommendations, but the feasibility and challenges associated with implementing these suggestions are not fully discussed. Recommendations such as “Encourage innovation and experimentation (Owners)” and “Establish clear circular economy goals and objectives (users/consumers)”, and so on, may be difficult to implement. A more thorough discussion of the practical challenges and how these recommendations could realistically be implemented would improve the paper
24.    To conclude the comments on Table 2, it should be clarified whether the recommendations provided are intended to be universally applicable or if they are context-specific. Given the diversity of regulatory, cultural, and market conditions across countries, such clarification is necessary to assess the practical transferability of these recommendations. 
25.    The section does not address propose future research directions, which could enhance the overall contribution of the research. The authors could point out approaches that could eliminate the limitations presented paper in future work. This would be a good starting point.

Author Response

2# Reviewer 
Revision 1 (General): The author emphasizes that the article stems from a PhD thesis. In this context, 
it is noteworthy that the supervisor is not listed as a co-author, which is uncommon in academic practice, 
where supervisors are frequently included as co-authors of publications derived from doctoral research.
Response 1: as the author, I appreciate the reviewer’s attention to this matter. As clarified in the revised 
Acknowledgements section, this article has been solely developed and written by the author, based on 
the doctoral research conducted under the general guidance of Prof. Antonello Monsù Scolaro. While 
his supervision during the thesis phase is gratefully acknowledged, the author prepared the manuscript 
independently without direct contributions warranting co-authorship. Furthermore, the PhD supervisor
is fully aware of the manuscript and has provided written and signed consent, which was submitted as 
part of the manuscript submission package per MDPI guidelines.
Revision 2 (Abstract): Abstract exceeds the 200 words limit
Response 2: The abstract has been revised per the reviewer’s comments. It can be found in lines 8-25.
Revision 3 (Abstract): Incomplete mention of the methodology used, leaving out important 
information about the study’s approach.
Response 3: The abstract has been revised per the reviewer’s comments. It can be found in lines 8-25.
Revision 4 (Abstract): Limited discussion of the significance or potential implications of the findings, 
missing the opportunity to highlight the practical importance of the study.
Response 4: The abstract has been revised per the reviewer’s comments. It can be found in lines 8-25.
Revision 5 (Introduction): The novelty and contribution of the paper should be highlighted.
Response 5: The introduction section has been revised per the reviewer’s comments. It can be found in 
lines 91-103.
Revision 6 (Introduction): It is strongly recommended mentioning the relationship of the paper with 
previous publication of the author.
Response 6: The introduction section has been revised per the reviewer’s comments. It can be found in 
lines 91-103. Furthermore, the relationship between these two contributions has already been written in 
lines 185-206. 
Revision 7 (Introduction): The statement presented in lines 82–83 relies solely on self-citation and 
may be reinforced by supporting evidence from other authors.
Response 7: The introduction section has been revised per the reviewer’s comments. It can be found in 
line 80. 
Revision 8 (Methodology): Lack of clarity in explaining the steps of the data analysis, making it 
difficult for readers to follow the research methodology.
Response 8: The methodology section has been revised per the reviewer’s comments. It can be found 
in lines 207-285.
Revision 9 (Methodology): Missing details or explanations about certain aspects of the analysis.
Response 9: The methodology section has been revised per the reviewer’s comments. It can be found 
in lines 207-285.
Revision 10 (Methodology): Insufficient details about the methodology used for data collection and 
analysis may affect the study’s transparency and reproducibility.
Response 10: The methodology section has been revised per the reviewer’s comments. It can be found 
in lines 207-285.
Revision 11 (Methodology): Regarding the problem identification stage, the author states that “this 
stage was not directly performed in this article, as it was built upon the authors’ previous publication 
[23]” [246–247]. It is strongly recommended that the scope and contributions of each publication be 
clearly delineated. Furthermore, it is generally considered inadequate to establish the core of a journal 
article based primarily on a conference paper, given that such papers typically do not undergo the same 
rigorous peer-review process as journal publications. Consequently, conference papers should be 
regarded as provisional outputs of ongoing research.
Response 11: The relationship between these two contributions has already been written in lines 185-
206 and 237-239. Furthermore, as noted in (Section 2), this article and the prior publication are derived 
from the author’s PhD thesis and represent two phases of a continuous research process. This statement 
can be found in lines 237-239.
Revision 12 (Methodology): Further clarification is requested regarding the statement in lines 261–
264 that “the model has not been formulated.”
Response 12: The methodology section has been revised per the reviewer’s comments. It can be found 
in lines 270-285.
Revision 13 (Methodology): The study derives its variables from prior international literature but does 
not clarify whether these are suitable for application in any specific national context. Beyond 
establishing relevance, the manuscript should address whether the selected variables are contextually 
appropriate. It remains unclear whether they are sufficiently comprehensive and representative for 
diverse settings, such as Asian countries like China, or if they primarily reflect conditions typical of 
European contexts. Additionally, the study does not indicate any attempt to investigate the inclusion of 
locally specific variables or the removal of potentially irrelevant ones to enhance contextual fit.
Response 13: The methodology section has been revised per the reviewer’s comments. It can be found 
in lines 277-285.
Revision 14 (Methodology): The manuscript claims to integrate real-world circular building case 
studies into the model to demonstrate the feasibility of system-wide transformation. However, the 
methodology behind this integration remains unclear. It is important to specify what data were extracted 
from the base articles, how these data were collected, and in what manner they were organized and 
systematized for incorporation into the model.
Response 14: The methodology section has been revised per the reviewer’s comments. It can be found 
in lines 253-269. Also, the results and discussion section has been revised, which can be found in 623-
629, 644-651, and 668-672. 
Revision 15 (Methodology): Since primary data was not collected at any time, how was the model 
validated?
Response 15: The methodology section has been revised per the reviewer’s comments. It can be found 
in lines 277-285.
Revision 16 (Results and Discussion): Further clarification is requested regarding the inclusion of 
“Environmental Impact Generation” and “Circular Economy Strategies” in the “Final System Dynamics 
Model Construction”. Specifically, it would be helpful to explain whether this refers to a methodological 
limitation, a future development step, or an intentional choice within the research design.
Response 16: The results and discussion section have been revised per the reviewer’s comments. It can 
be found in lines 527-531.
Revision 17 (Results and Discussion): The section lacks a clear synthesis of the main findings, making 
it challenging to identify the key takeaways from the results.
Response 17: The results and discussion section have been revised per the reviewer’s comments. It can 
be found in lines 518-521, 617-620, and 828-831. 
Revision 18 (Results and Discussion): Failing to compare findings with existing research in the field 
limits the context and significance of the study.
Response 18: The results and discussion section have been revised per the reviewer’s comments. It can 
be found in lines 832-855
Revision 19 (Results and Discussion): The implications of the study are not enough.
Response 19: The results and discussion section has been revised according to the reviewer’s 
comments. It can be found in lines 832-855. 
Revision 20 (Conclusion): It has redundant passages that make the text confusing.
Response 20: The conclusions section has been revised per the reviewer’s comments. It can be found 
in lines 860-926. 
Revision 21 (Conclusion): The content of the conclusion section aligns more closely with what is 
typically expected in a discussion section. It is therefore recommended that a new subsection, titled 4.3 
“Discussion,” be inserted before the conclusion. A substantial portion of the current conclusion text 
should be relocated to this new subsection to ensure structural clarity and to maintain the distinct 
purpose of each section. Specifically, the content between lines 830–856, along with Table 2, should be 
reviewed to assess its pertinence within the conclusion section.
Response 21: The conclusions section has been revised per the reviewer’s comments. It can be found 
in lines 860-926. 
Revision 22 (Conclusion): The origin of the practical recommendations presented in Table 2 is unclear. 
It should be specified whether these recommendations are original contributions from the authors or if 
they were derived from existing literature. It would be interesting to submit it to experts to validate the 
recommendations or to add new recommendations.
Response 22: The conclusions section has been revised per the reviewer’s comments. It can be found 
in lines 877-879. 
Revision 23 (Conclusion): Still on table 2. A feasibility discussion of practical recommendations is still 
needed. Specifically, the paper presents 47 practical recommendations, but the feasibility and challenges 
associated with implementing these suggestions are not fully discussed. Recommendations such as 
“Encourage innovation and experimentation (Owners)” and “Establish clear circular economy goals 
and objectives (users/consumers)”, and so on, may be difficult to implement. A more thorough 
discussion of the practical challenges and how these recommendations could realistically be 
implemented would improve the paper.
Response 23: The conclusions section has been revised per the reviewer’s comments. It can be found 
in lines 910-926. 
Revision 24 (Conclusion): To conclude the comments on Table 2, it should be clarified whether the 
recommendations provided are intended to be universally applicable or if they are context-specific. 
Given the diversity of regulatory, cultural, and market conditions across countries, such clarification is 
necessary to assess the practical transferability of these recommendations.
Response 24: The conclusions section has been revised per the reviewer’s comments. It can be found 
in lines 910-926. 
Revision 25 (Conclusion): The section does not address propose future research directions, which 
could enhance the overall contribution of the research. The authors could point out approaches that 
could eliminate the limitations presented paper in future work. This would be a good starting point.
Response 25: The conclusions section has been revised per the reviewer’s comments. It can be found 
in lines 910-926. 
• Revisions performed according to the other reviewers have been highlighted in yellow and can 
be found in the revised manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Dear author,

First, I congratulate you on the revised manuscript. It has been significantly improved.

However, I would like to reiterate the importance of providing complete methodological details to ensure the study’s reproducibility. In this regard, the response to my previous Revision 14 (Methodology) remains insufficient, particularly concerning the process of data extraction from the case studies, which still lacks clarity.

Additionally, I reinforce the suggestion that Table 2 should be carefully reviewed in terms of its pertinence to the conclusion section. To ensure a clear, concise, and strong conclusion, I recommend moving Table 2 — along with its discussions — to the subsection 4.4. If necessary, you may refer to it briefly within the conclusion section.

Congratulations on your paper.

Best regards,

Author Response

2# Reviewer 
Revision 1: However, I would like to reiterate the importance of providing complete methodological 
details to ensure the study’s reproducibility. In this regard, the response to my previous Revision 141
(Methodology) remains insufficient, particularly concerning the process of data extraction from the case 
studies, which still lacks clarity.
Response 1: The article has been revised according to the reviewer’s comments, which can be found in 
lines 645-654.
Revision 2 : Additionally, I reinforce the suggestion that Table 2 should be carefully reviewed in terms 
of its pertinence to the conclusion section. To ensure a clear, concise, and strong conclusion, I 
recommend moving Table 2 — along with its discussions — to the subsection 4.4. If necessary, you 
may refer to it briefly within the conclusion section.
Response 2: The article has been revised according to the reviewer’s comments, which can be found in 
lines 855-876, 889-890, and 905-909. 

Author Response File: Author Response.pdf