Housing Design for Circular Economy and Sustainability

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. Figure 14 is small and blurry.
2. The format of tables and size of letter should be consistent throughout the manuscript.
3. There are 2 figure 13 in the manuscript.
4. Formulas should be numbered.
5. Figure 12 is unclear and has many unnecessary details.
6. Figure 11 is not explained or commented on in the manuscript.
7. What is the relationship between figures 11 and 12? Should the author clarify this in the article?
8. Figure 3 has no comments in the manuscript.

Author Response

Author’s comments to reviewer 1

Dear Reviewer,

Thank you very much for taking the time to review the paper. Your comments are very valuable, and I have attempted to answer them all.

The following aspects have been improved:

Structure of the article

Restructuring and additional revisions, the following steps have been taken:

1. The abstract has been improved. I map out the step-by-step logical progression of the article.
2. I added a new methods section, which improves structuring research, explains processes, and ensures clarity. “First, the literature review defines CE in the construction sector, establishes its theoretical foundation, and explores its feasibility in housing. Second, the Domus Ex Machina prefab project serves as a case study to analyze the implementation of CE strategies. Third, “design for disassembly “(DfD) enhances modularity, material recovery, and waste reduction. Forth, a life cycle assessment (LCA) quantifies the environmental benefits by evaluating carbon emissions, energy savings, and pollutant reduction. Additionally, a life cycle cost analysis (LCCA) assesses the financial sustainability of CE in housing by considering initial construction, operational, maintenance, and dismantling costs. Finally, the author has performed research that discusses the scientific contributions of other experts and identifies three difficulties to circular economy in housing development.”
3. In the economic feasibility section, I compared data between Domus Ex Machina and other conventional homes in various aspects, such as cost, construction period, etc. Also, Domus Ex Machina's full life cycle cost analysis, including initial construction, operation and maintenance and dismantling and recycling costs, to assess economic sustainability.
4. In the discussion section, (1) analyzing the support or restriction of current construction-related policies on circular economy residential design (2) Combine the latest construction industry trends and technological breakthroughs (3) the practical problems encountered by Domus Ex Machina in the implementation of DfD.

Figures:

Figure 14 is small and blurry.

Figure 14 is larger now. The format of tables and size of letter is consistent throughout the manuscript.

There are 2 figures 13 in the manuscript.

Corrected

Formulas should be numbered.

Corrected: “Formular 1: Embodied Carbon Emission=carbon factor x area x thickness x density... Formular 2: yearly energy loss per unit area = (area x u-value) x heating degree daytime; for Domus Ex Machina, this calculation yields an energy loss ranging from 5.92 kWh/m²/year to 6.72 kWh/m²/year… Formular 3: Carbon emission due to heat loss through envelope = annual heat loss per unit area x emissions factor.”

Figure 12 is unclear and has many unnecessary details.
Explained: “The figure 12 shows a modern, minimalist interior with prefabricated modular elements designed for efficient assembly without traditional drywall and paint. The walls, built-in shelving, and cabinetry appear to be composed of pre-finished panels that seamlessly clip together.”

Figure 11 is not explained or commented on in the manuscript.

Explained: “As figure 11 shown, the flow starts with extraction of raw materials, which are then sent to the refining process. The refined materials are used for building or manufacturing new products. Once in use, products may either generate waste or enter reuse and recycle pathways. Reused materials directly reintegrate into the system, while recycled materials return to the refining process. Any waste that cannot be recovered is sent for disposal. This diagram emphasizes sustainability and resource efficiency, illustrating the importance of circular design to minimize waste and maximize material recovery.”

What is the relationship between figures 11 and 12? Should the author clarify this in the article?

Explained: “The figure 11 represents the lifecycle of materials through extraction, refining, use, waste, recycling, and reuse to minimize disposal. It provides a macro-level view of sustainable resource management across industries. The figure 12 shows a modular, prefabricated interior, where clip-together panels replace drywall and paint. While the figure 11 explains the theory of circular economy, the figure 12 demonstrates its practical application in architecture. Both figures promote sustainability through efficient material use and reuse.”

Figure 3 has no comments in the manuscript.

Explained: “As figure 3 shown, at the top, "build to last" represents the most sustainable approach which minimizes material use. Below, "repair & reuse" encourages extending product lifespan through maintenance. "Reuse same product" suggests repurposing items without modifications. At the base, "Recycle raw materials" is the least preferred option, as it requires energy to break down materials. The pyramid highlights the priority of longevity, reuse, and recycling in sustainable design and circular economy principles.”

Reference:

The number of references was increased to 40 to further support the arguments and research.

Thank you and best regards,

AF

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The article focuses on residential building sustainability and explores the importance of incorporating circular economy principles. The Domus Ex Machina project is used as an example, incorporating Brand's Shearing Layers model to analyze the lifespan of different building components, reduce disruption to other layers during maintenance, and reduce waste generation. The “Design for Disassembly” (DfD) concept was adopted to simplify the construction and disassembly process and promote material recycling through the design of prefabricated, dry-connected and demountable partitions. At the same time, the project focuses on energy conservation by selecting low energy-containing or recycled materials, optimizing the building structure and envelope, and reducing energy consumption and carbon emissions to achieve the design goal of sustainable living spaces. The article's research suggests that the current linear economic model is not sustainable in the construction sector and that circular economy is a viable alternative. Utilizing Brand's Shearing Layer model and the 'Design for Disassembly' (DfD) methodology can reduce construction waste and increase flexibility. The Domus Ex Machina project implements sustainable concepts in all phases of the design, demonstrating good The Domus Ex Machina project demonstrates adaptability and recyclability by implementing sustainable concepts in all phases of the design. This makes sense, but the following questions still need to be answered:

1)       Case comparisons can be enriched: by adding detailed comparative data between Domus Ex Machina and other conventional homes or similar sustainable homes in various aspects, such as cost, construction period, etc., in order to highlight its advantages.

2)       Optimize the model application elaboration: further illustrate the differences in the application of Shearing Layers model in different types of houses and complex building environments to enhance its universality.

3)       Reinforcement of the details of DfD practice: Supplementing the practical problems and solutions encountered by Domus Ex Machina in the implementation of DfD, providing reference for other projects.

4)        Improve economic feasibility analysis: Join Domus Ex Machina's full life cycle cost analysis, including initial construction, operation and maintenance and dismantling and recycling costs, to assess economic sustainability.

5)       Deepen the quantification of environmental benefits: in addition to carbon emissions, supplement other pollutant emission reduction data to comprehensively present the positive impact of the project on the environment.

6)       Expand user needs research: Conduct research on user acceptance and experience of Domus Ex Machina design, and incorporate the results into design recommendations.

7)       Update industry dynamics: Combine the latest construction industry trends and technological breakthroughs, and explain how circular economy design can be better integrated with them.

8)       Refinement of material performance description: detailed description of the performance indicators and long-term stability of the recycled materials used in the project to enhance credibility.

9)        Optimize chart presentation: Improve the labeling and interpretation of charts to make data more intuitive and easy to understand, and enhance the efficiency of information communication.

10)    Supplementary Policy Impact Discussion: Analyze the support or restriction of current construction-related policies on circular economy residential design, and propose strategies to cope with them.

Author Response

Author’s comments to reviewer 2

Dear Reviewer,

Thank you very much for taking the time to review the paper. Your comments are very valuable, and I have attempted to answer them all.

The following aspects have been improved:

Structure of the article

Restructuring and additional revisions, the following steps have been taken:

1. The abstract has been improved. I map out the step-by-step logical progression of the article.
2. I added a new methods section, which improves structuring research, explains processes, and ensures clarity. “First, the literature review defines CE in the construction sector, establishes its theoretical foundation, and explores its feasibility in housing. Second, the Domus Ex Machina prefab project serves as a case study to analyze the implementation of CE strategies. Third, “design for disassembly “(DfD) enhances modularity, material recovery, and waste reduction. Forth, a life cycle assessment (LCA) quantifies the environmental benefits by evaluating carbon emissions, energy savings, and pollutant reduction. Additionally, a life cycle cost analysis (LCCA) assesses the financial sustainability of CE in housing by considering initial construction, operational, maintenance, and dismantling costs. Finally, the author has performed research that discusses the contributions of other experts and identifies difficulties to circular economy in housing development.”
3. In the economic feasibility section, I compared data between Domus Ex Machina and other conventional homes in various aspects, such as cost, construction period, etc. Also, Domus Ex Machina's full life cycle cost analysis, including initial construction, operation and maintenance and dismantling and recycling costs, to assess economic sustainability.
4. In the discussion section, (1) analyzing the support or restriction of current construction-related policies on circular economy residential design (2) Combine the latest construction industry trends and technological breakthroughs (3) the practical problems encountered by Domus Ex Machina in the implementation of DfD.

Deepen the quantification of environmental benefits, except carbon emissions

1. Reducing leachate contamination and protecting local water quality
2. Using 30% reused materials in new building could reduce benzene, formaldehyde, and volatile organic compound air pollution by 40%.

Figures

1. I added more explanations of some figures in the text, ensuring their clarity and understandable.
2. Some figures’ captions have been simplified.

 

Description of the performance indicators and long-term stability of the recycled materials used in the project.

This article primarily focuses on innovative design strategies, such as the design for disassembly and the layered model, which contribute to enhancing the long-term stability of housing lifespan. However, detailed scientific data on the long-term stability of the recycled materials used in the project is not extensively covered.

Further illustrate the differences in the application of Shearing Layers model in different types of houses and complex building environments

This article primarily discusses the use of the Shearing Layers model in townhouses and single-family homes, especially in the Domus Ex Machina prefab project.  While the model is addressed in this context, additional investigation into its application to various dwelling kinds and complex building environments is outside the scope of this paper.

Research on user acceptance and experience of Domus Ex Machina design and incorporate the results into design recommendations

Currently, there is no available data on user acceptance and experience of the Domus Ex Machina design. As a result, this aspect is not incorporated into the design recommendations in this article.

 

Thank you and best regards,

AF

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This study focuses on the importance of integrating circular economy principles in residential buildings and, through relevant research, identifies its advantages. The structure of this article is complete, and the ideas are clear, but there is still room for improvement in some of the details described.

Tips：

1. The abstract section explains the key content of this article, but the language is stiff and lacks coherence. The author should improve the abstract section to make the content more complete and understandable.
2. The article effectively combines image materials to explain the research content, but some image titles are too long and appear complex. It is recommended that the author simplify the title content to make it easier for readers to grasp the key points.
3. Some of the image formats used in the article are simple and single. The author can improve the images to display the relevant content more thoroughly. In some explanatory content, the proportion of images is relatively large. Adjusting the proportion of text and pictures appropriately is recommended.
4. The reference format is concise and unified, but this article has a tiny number of references. It is recommended that the author add some relevant literature to explain the research content and find some of the latest research results.
5. The conclusion provides a detailed summary of the research results but lacks a complete explanation of the overall research content. It is recommended that the author further improve the conclusion section to make it more concise and accurate in introducing the research content.

Author Response

Author’s comments to reviewer 3

Dear Reviewer,

Thank you very much for taking the time to review the paper. Your comments are very valuable, and I have attempted to answer them all.

The following aspects have been improved:

 

Abstract

The abstract section explains the key content of this article, but the language is stiff and lacks coherence.

The abstract has been improved, and its project goals, aims, and measures are now clearly presented.

 

Figures

• The article effectively combines image materials to explain the research content, but some image titles are too long and appear complex.

Some figures’ captions have been simplified.

• Some of the image formats used in the article are simple and single. The author can improve the images to display the relevant content more thoroughly. In some explanatory content, the proportion of images is relatively large. Adjusting the proportion of text and pictures appropriately is recommended.

I explained some figures in the text, ensuring their clarity and understandable.

References

This article has a tiny number of references. It is recommended that the author add some relevant literature to explain the research content and find some of the latest research results.

I added more references to 40 and further researched : (1) analyzing the support or restriction of current construction-related policies on circular economy residential design (2) Combine the latest construction industry trends and technological breakthroughs (3) the practical problems encountered by Domus Ex Machina in the implementation of DfD.

Conclusion

The conclusion provides a detailed summary of the research results but lacks a complete explanation of the overall research content.

I further improved the conclusion section which is more concise and accurate in introducing the research content.

Thank you and best regards,

AF

 

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The paper discusses circular economy and sustainability principles in housing design, using a case study of a modular housing system designed by the Author.

However, the methodology and the research questions are not clearly stated, and the ultimate goal of the article is not easily discernible. Current theoretical notions of circularity in the construction process and consolidated design approaches to pursue circular economy are introduced and then exemplified through the solutions adopted in the residential project presented. The technological and spatial features of the project are described without delving into depth or highlighting the original or innovative design choices or methodologies.

Perhaps a more thorough analysis of the project, demonstrating how and to what extent it adheres to circular economy principles—while also discussing its limitations and potential—could enhance the article’s scientific impact

Alternatively, incorporating details on the design development process, trade-offs among different options, or insights into future applications and economic feasibility could strengthen the discussion.

Author Response

Author’s comments to reviewer 4

Dear Reviewer,

Thank you very much for taking the time to review the paper. Your comments are very valuable, and I have attempted to answer them all.

The following aspects have been improved:

 

Structure of the article

Restructuring and additional revisions, the following steps have been taken:

• The methodology and the research questions are not clearly stated, and the ultimate goal of the article is not easily discernible.

1. The abstract has been improved and that the project goals, aims, and measures are now clearly presented.
2. I added a new methods section, which improves structuring research, explains processes, and ensures clarity. “First, the literature review defines CE in the construction sector, establishes its theoretical foundation, and explores its feasibility in housing. Second, the Domus Ex Machina prefab project serves as a case study to analyze the implementation of CE strategies. Third, “design for disassembly “(DfD) enhances modularity, material recovery, and waste reduction. Forth, a life cycle assessment (LCA) quantifies the environmental benefits by evaluating carbon emissions, energy savings, and pollutant reduction. Additionally, a life cycle cost analysis (LCCA) assesses the financial sustainability of CE in housing by considering initial construction, operational, maintenance, and dismantling costs. Finally, the author has performed research that discusses the scientific contributions of other experts and identifies three difficulties to circular economy in housing development.”

 

• A more thorough analysis of the project, demonstrating how and to what extent it adheres to circular economy principles—while also discussing its limitations and potential—could enhance the article’s scientific impact

1. In the economic feasibility section, I compared data between Domus Ex Machina and other conventional homes in various aspects, such as cost, construction period, etc. Also, Domus Ex Machina's full life cycle cost analysis, including initial construction, operation and maintenance and dismantling and recycling costs, to assess economic sustainability.
2. In the discussion section, (1) analyzing the support or restriction of current construction-related policies on circular economy residential design (2) Combine the latest construction industry trends and technological breakthroughs (3) the practical problems encountered by Domus Ex Machina in the implementation of DfD.

 

Deepen the quantification of environmental benefits, except carbon emissions

1. Reducing leachate contamination and protecting local water quality
2. Using 30% reused materials in new building could reduce benzene, formaldehyde, and volatile organic compound air pollution by 40%.

 

Figures

1. I added more explanations of some figures in the text, ensuring their clarity and understandable.
2. Some figures’ captions have been simplified.

 

 

Thank you and best regards,

AF

Author Response File: Author Response.pdf

Reviewer 5 Report

Comments and Suggestions for Authors

Manuscript Title: Housing Design for Circular Economy and Sustainability  

Author: Avi Friedman  

 

1. Scientific Merit and Novelty  

Scientific Merit: The topic of integrating circular economy (CE) principles into residential architecture is highly relevant, addressing pressing environmental challenges such as resource depletion and construction waste. The study aligns with global sustainability goals and highlights critical issues like material reuse and energy efficiency.  

Novelty: While the paper introduces concepts like "Design for Disassembly (DfD)" and Brand’s Shearing Layers Model, these frameworks are well-established in existing literature. The Domus Ex Machina prototype, though presented as innovative, lacks originality in its application of CE principles. The work does not propose novel methodologies or theoretical advancements beyond incremental adaptations of existing ideas.  

 

Key Weaknesses:  

- Over-reliance on established concepts without significant theoretical or methodological innovation.  

- Limited discussion of how this study advances beyond prior research on CE in architecture.  

 

2. Comprehensiveness and Accuracy of Literature Review  

Comprehensiveness: The review covers foundational CE literature (e.g., the "six Rs" framework) and regional practices (e.g., Germany, Japan). However, recent advancements in circular construction (e.g., 2020–2024 studies on modular prefabrication or digital tools for material tracking) are inadequately addressed.  

Accuracy: Citations are generally appropriate but lack critical engagement. For example, the Shearing Layers Model is described without addressing its limitations (e.g., scalability in diverse climates or cost implications).  

 

Key Weaknesses:  

- Insufficient inclusion of cutting-edge research, particularly post-2020 studies.  

- Superficial critique of cited frameworks, failing to identify gaps that the study aims to fill.  

 

3. Methodological Rigor and Appropriateness  

Appropriateness: The use of DfD and Shearing Layers is theoretically suitable for CE-focused housing design. However, the Domus Ex Machina case study lacks empirical validation.  

Rigor: Methodological details are sparse. For instance, the "dry connection construction method" is mentioned but not illustrated with technical specifications or comparative analyses. Calculations for embodied carbon (e.g., Figure 13) omit data sources and assumptions, undermining reproducibility.  

 

Key Weaknesses:  

- Insufficient detail on design implementation (e.g., prefabrication techniques, material sourcing).  

- No validation through prototypes, simulations, or real-world testing.  

 

4. Credibility and Reproducibility of Results  

Credibility: Claims about energy efficiency (e.g., 64% improvement in row homes) rely on theoretical calculations without empirical evidence. The absence of experimental data or case studies weakens credibility.  

Reproducibility: Incomplete documentation (e.g., U-value assumptions, material densities) prevents independent verification of results.  

 

Key Weaknesses:  

- Over-reliance on idealized calculations unsupported by real-world measurements.  

- Lack of transparency in key parameters (e.g., carbon factors, insulation performance).  

 

5. Scientific and Comprehensive Data Analysis  

Scientific Analysis: The use of formulas (e.g., embodied carbon emissions) is rudimentary and lacks statistical rigor. No sensitivity analysis or error margins are provided.  

Comprehensiveness: Data focuses narrowly on energy loss and carbon metrics, omitting critical aspects like cost analysis, user feedback, or lifecycle assessments.  

 

Key Weaknesses:  

- Simplistic calculations that ignore variables such as transportation emissions or labor costs.  

- Selective reporting of favorable outcomes without addressing potential trade-offs (e.g., higher upfront costs for DfD).  

 

6. Logical Soundness of Conclusions  

Logical Consistency: Conclusions align with the study’s objectives but are overly optimistic. Claims about Domus Ex Machina’s adaptability and sustainability are not substantiated by evidence.  

Critical Flaws: The conclusion fails to address limitations (e.g., scalability, regulatory barriers) or compare results with existing CE housing models.  

 

Key Weaknesses:  

- Unsupported assertions about the prototype’s superiority over traditional designs.  

- No discussion of practical challenges (e.g., market adoption, construction industry resistance).  

 

7. Structure and Writing Quality  

Structure: The paper follows a standard format but suffers from redundancy (e.g., repeated descriptions of Shearing Layers). Figures are poorly labeled (e.g., multiple "Figure 13" entries), causing confusion.  

Writing Quality: Grammatical errors (e.g., "six Rs notion" vs. "six Rs’ notion") and ambiguous phrasing (e.g., "recovery is intricately connected") detract from clarity.  

 

Key Weaknesses:  

- Inconsistent figure numbering and vague captions.  

- Language issues that hinder readability and professionalism.  

 

8. Contribution and Practical Implications  

Academic Contribution: The study reiterates known CE principles without advancing theoretical or practical knowledge. The Domus Ex Machina prototype, while illustrative, offers no measurable breakthroughs.  

Practical Relevance: The absence of cost-benefit analyses, stakeholder interviews, or policy recommendations limits real-world applicability.  

 

Key Weaknesses:  

- No demonstration of how the design addresses systemic barriers (e.g., regulatory frameworks, consumer behavior).  

- Lack of scalability assessment for diverse socioeconomic contexts.  

 

 

Comments on the Quality of English Language

The English could be improved to more clearly express the research.

Author Response

Author’s comments to reviewer 5

Dear Reviewer,

Thank you very much for taking the time to review the paper. Your comments are very valuable, and I have attempted to answer them all.

The following aspects have been improved:

Structure of the article

Restructuring and additional revisions, the following steps have been taken:

1. The abstract has been improved. I map out the step-by-step logical progression of the article.
2. I added a new methods section, which improves structuring research, explains processes, and ensures clarity. “First, the literature review defines CE in the construction sector, establishes its theoretical foundation, and explores its feasibility in housing. Second, the Domus Ex Machina prefab project serves as a case study to analyze the implementation of CE strategies. Third, “design for disassembly “(DfD) enhances modularity, material recovery, and waste reduction. Forth, a life cycle assessment (LCA) quantifies the environmental benefits by evaluating carbon emissions, energy savings, and pollutant reduction. Additionally, a life cycle cost analysis (LCCA) assesses the financial sustainability of CE in housing by considering initial construction, operational, maintenance, and dismantling costs. Finally, the author has performed research that discusses the contributions of other experts and identifies difficulties to circular economy in housing development.”
3. In the economic feasibility section, I compared data between Domus Ex Machina and other conventional homes in various aspects, such as cost, construction period, etc. Also, Domus Ex Machina's full life cycle cost analysis, including initial construction, operation and maintenance and dismantling and recycling costs, to assess economic sustainability.

Further illustrate the differences in the application of Shearing Layers model in different types of houses and complex building environments

This article primarily discusses the use of the Shearing Layers model in townhouses and single-family homes, especially in the Domus Ex Machina prefab project.  While the model is addressed in this context, additional investigation into its application to various dwelling kinds and complex building environments is outside the scope of this paper.

Credibility and Reproducibility of Results 

I acknowledge that the data presented reflects an ideal scenario and agree that the study lacks empirical validation, limiting the credibility and reproducibility of the results. Additionally, I recognize the concern regarding selective reporting of favorable outcomes without fully addressing potential trade-offs. However, due to practical constraints, obtaining more comprehensive scientific data, including real-world measurements, is not currently feasible within the scope of this research.

Unsupported assertions about the prototype’s superiority over traditional designs and no discussion of practical challenges (e.g., market adoption, construction industry resistance). 

In the discussion section, (1) analyzing the support or restriction of current construction-related policies on circular economy residential design (2) combining the latest construction industry trends and technological breakthroughs (3) the practical problems encountered by Domus Ex Machina in the implementation of DfD.

Research on user acceptance and experience of Domus Ex Machina design and incorporate the results into design recommendations

Currently, there is no available data on user acceptance and experience of the Domus Ex Machina design. As a result, this aspect is not incorporated into the design recommendations in this article.

 

Thank you and best regards,

AF

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

None

Reviewer 4 Report

Comments and Suggestions for Authors

The new version of the paper includes a more integrated relationship of the case study to the general scientific and debate consistent with the potentials and limits of the regulatory and industrial sector. New arguments have been added to the discussion as well as a deeper understanding of the project presented.

The new contents have been organized according to a clearer methodological structure and identification of the final goals of the contribution.

Reviewer 5 Report

Comments and Suggestions for Authors

Accepted

Comments on the Quality of English Language

Accepted