Radiant Floor Cooling Systems: A Critical Review of Modeling Methods
Round 1
Reviewer 1 Report
This paper reviews the modeling methods, technical standards and accuracy of radiant floor cooling system, discusses the factors that most affect the performance of the floor, summarizes two main modeling methods, and is a relatively complete review of the modeling methods of radiant floor cooling system. However, there are still the following major problems in this paper:
1 Some sections of the article are incorrectly marked and some are misspelled.
2 This paper analyzes the main factors affecting the floor radiant cooling system and lists other factors, but lacks analysis of other factors. For example, in the summary of the system modeling method, there is insufficient analysis of how to improve the floor condensation moisture.
3 Many different modeling methods are mentioned in this paper, but the advantages and disadvantages of these methods are not discussed and compared in detail.
4 Two main modeling methods are mentioned in the section of model methods, but the specific description and application range of these methods are not given.
5 In the conclusion, the paper mentions the need for modeling methods, but does not give specific suggestions and methods to meet these needs.
6 The results and recommendations of some studies are mentioned in the paper, but no specific data and examples are given to support these results and recommendations.
7 The sixth chapter describes too much and has no innovative ideas, so it is suggested to simplify the narration.
8 Overall, the paper discusses the system modeling method comprehensively, but it is insufficient in summary and refining and putting forward innovative views.
So I think this paper needs to be reexamined after major revisions.
Some sections of the article are incorrectly marked and some are misspelled.
Author Response
Dear Reviewer 1,
We would like to thank you very much for your time and valuable feedback. Your suggestions and criticisms have pushed us to significantly improve the quality of the paper, which we believe is now more scientifically sound and consistent with our original intent. We hope that the improvements we have made are in line with your suggestions and that the revised article is satisfactory.
We will now respond to your review point by point.
R: “This paper reviews the modeling methods, technical standards and accuracy of radiant floor cooling system, discusses the factors that most affect the performance of the floor, summarizes two main modeling methods, and is a relatively complete review of the modeling methods of radiant floor cooling system.”
A: Thank you for your positive feedback on the completeness of the review and thank you for recognizing the main scope and distinguishing features of our review on modeling methods of radiant floor cooling systems.
R: “However, there are still the following major problems in this paper”.
A: We will now attempt to address the issues you have identified and refine the paper where necessary.
R: “1 Some sections of the article are incorrectly marked and some are misspelled.”
A: It is true that some sections were mislabeled. Thank you for pointing out our oversight, which went unnoticed during our review stages. In the text, on page 11, line 428 (see text with highlighted changes), we changed the section index 3.4. to the correct 3.5.
We have also revised some of the section and subsection headings to improve readability: “Methods Overview” on page 11 became “Overview of the Methods”, “Analysis of the Most Significant Modeling Aspects” on page 18 became “Analysis of Key Modeling Aspects”, and “Modeling Accuracy Considerations” on page 22 became “Considerations on Modeling Accuracy”.
R: “2 This paper analyzes the main factors affecting the floor radiant cooling system and lists other factors, but lacks analysis of other factors. For example, in the summary of the system modeling method, there is insufficient analysis of how to improve the floor condensation moisture.”
A: In addition to the main factors involved in modeling radiant floor systems - i.e., conduction within the slab and radiant heat transfer from the surface to the surroundings - the paper highlights other important factors that have a direct impact on system performance, such as the presence of solar radiation entering through glazed surfaces, internal gains, natural convection at the floor surface, and the presence of furniture in the cooled space. However, the paper does not deal extensively with methodological analyses aimed at addressing some of these issues. This is due to the lack of consensus in the literature on a definitive approach to incorporating these factors into models. For example, the actual influence of the convective exchange and the presence of furniture on real-world applications have not yet been comprehensively addressed in the literature. In fact, their effect is inherently case-specific, and their improvement or degradation of performance is not easily schematized, as it strongly depends on the specific boundary conditions. Consequently, this emerges as a prominent gap requiring attention within the scientific literature. While existing studies emphasize the importance of these factors, a universally applicable modeling approach has yet to be proposed. To clarify the text, considerations similar to those just reported have been included in the paper on page 22 from line 803 to line 809.
As for condensation on the floor, it is a phenomenon that should be avoided in order to guarantee the correct operation of the radiant cooling terminal. To prevent it, the supply temperatures to the pipes in the floor should be sufficiently high to maintain a floor surface temperature above the dew point of the ambient air. Therefore, control strategies should include a modeling method capable of determining the minimum floor surface temperature and, consequently, the most appropriate supply temperature from the chiller. For additional safety, an appropriate safety margin should be included in the evaluation.
Because of this requirement, the supply temperature used may not be sufficient to meet the cooling load required by the building. To avoid this, additional dedicated terminals could be used to handle the latent load, thus increasing the dew point temperature of the ambient air.
To enable this control and avoid condensation, it is fundamental to have a model capable of estimating the temperature of the coldest point on the floor surface, as this is the point where condensation would occur. Therefore, models that consider the floor surface as a single node are insufficient for this purpose, unless a corrective approach is used to determine the lowest temperature starting from the average surface temperature.
These considerations have been included in the paper on page 18, from line 643 to line 649, to clarify the importance of condensation control during system operation.
R: “3 Many different modeling methods are mentioned in this paper, but the advantages and disadvantages of these methods are not discussed and compared in detail.”
A: We now acknowledge this as a major gap in the paper, as the other reviewer also raised a similar criticism. We will provide the same response to both of you.
The review paper analyzes a total of 28 modeling methods for radiant floor cooling systems. The methods were divided into two main categories, and the specific features of each model were highlighted and summarized in tables and Sankey diagrams.
Each model has its own unique features, which may become advantages or disadvantages depending on the specific application for which it is intended.
However, in order to provide a comparative analysis between the different methods, a summary paragraph has been added to Section 3, page 12, lines 453-468, highlighting general considerations about the strengths and weaknesses of each class of methods.
R: “4 Two main modeling methods are mentioned in the section of model methods, but the specific description and application range of these methods are not given.”
A: The main categorization of modeling methods is made in terms of the target phenomenon they describe. Following this criterion, two main categories have been identified: the models that focus only on the conductive heat transfer within the floor, considering the surroundings as fixed boundary conditions, and the integrated models that couple the floor with the rest of the building, considering their mutual interactions. The two types of models are somewhat similar in that the former are included in the more comprehensive representation provided by the latter. However, the scope and application areas for which they are intended are different. Floor conduction models are suitable for the optimal design of the emitting terminals, focusing on specific aspects of the radiant floor system. On the other hand, coupled floor-building models are primarily intended for complete simulations of the system, typically dynamic, that can be used to evaluate performance in specific configurations or for integration into control applications.
To make the distinction between the two classes of models more explicit, a paragraph has been added to the text on page 14, lines 530-534, which explains and summarizes the content presented here.
R: “5 In the conclusion, the paper mentions the need for modeling methods, but does not give specific suggestions and methods to meet these needs.”
A: As an important future direction, we emphasized the need for parametrizable yet complete modeling methods. These methods should include a realistic schematization of the main phenomena and effects that occur in real-world scenarios. Nevertheless, they should maintain a straightforward approach that allows easy implementation in practical case studies without requiring a full geometric representation of the configuration, which can be difficult to obtain.
To pursue these future developments, we propose two main approaches.
First, in order to satisfy the need for a correct description of the effects usually omitted or superficially treated by models, such as convection or the presence of furniture, we believe that the most important methodology should be the execution of experimental studies and campaigns. In fact, software simulations may not be sufficient to properly describe these phenomena. Since their effects are usually strongly influenced by instabilities and other non-ideal effects, practical studies may provide the most appropriate means to capture the physical behavior and establish correlations or correction coefficients for integration into models.
Such an approach has been pursued by Pantelic et al. in [47]. However, to fill the gap, many different such experimental campaigns are needed.
On the other hand, to model case studies without requiring highly specific knowledge of the configuration, a large-scale field monitoring campaign could serve as a valuable tool. The collection of operational data from a wide variety of practical applications could facilitate the development of novel techniques for modeling buildings equipped with radiant floor cooling systems. By combining the accumulated knowledge of the physical phenomena governing the operation of radiant floor systems with real-world data obtained from field measurements, gray-box techniques may prove to be an effective strategy for modeling these scenarios. This approach is consistent with recent market trends, as HVAC&R system manufacturers are increasingly incorporating monitoring devices into their installations.
These suggestions were not previously included in our paper. Therefore, thanks to your feedback, we have decided to add two new paragraphs dedicated to them, which have been placed on page 25, on lines 977-982 and lines 990-994.
R: “6 The results and recommendations of some studies are mentioned in the paper, but no specific data and examples are given to support these results and recommendations.”
A: We agree with this observation. Accordingly, to enrich the discussion of modeling methods and to provide a more complete presentation of their results, several changes have been made to the text in Sections 3 and 4. Where relevant, the description of some of the modeling methods presented in the literature has been expanded to include supporting quantitative information and examples, as well as details of the applications studied.
R: “7 The sixth chapter describes too much and has no innovative ideas, so it is suggested to simplify the narration.”
A: Again, we agree with the feedback. Previously, Section 6 consisted mainly of a summary of existing literature without introducing any substantial new ideas. To address this, we have simplified and shortened the narrative. In addition, we have added our original contribution to the section by incorporating critical insights into software modeling methodologies. It has been placed on page 23, starting at line 875.
R: “8 Overall, the paper discusses the system modeling method comprehensively, but it is insufficient in summary and refining and putting forward innovative views.
So I think this paper needs to be reexamined after major revisions.”
A: In light of the adjustments we have made to address the feedback provided in the previous seven comments, we now believe that our review paper effectively accomplishes the tasks of summarizing, refining, and introducing innovative perspectives to the existing literature on modeling radiant floor cooling systems. Your comments have been extremely helpful in correcting omissions in the text, improving the description of phenomena involved in the operation of radiant systems, facilitating discussions and comparisons of model strengths and weaknesses, incorporating additional data and quantitative insights from studies, and drawing attention to what we have identified as future developments in this area of research, by also suggesting possible avenues for pursuing them. We have also addressed your recommendation for moderate English editing to improve the readability and overall impact of the text.
Reviewer 2 Report
The paper provides a comprehensive review of the modeling methods for radiant floor cooling systems. It covers a wide range of methods and discusses their strengths and limitations. However, the paper lacks specific implementation details, comparative analysis of the methods, and discussions on the limitations and future research directions.
Manuscript: energies-2562198
Title: Radiant Floor Cooling Systems: A Critical Review of Modeling Methods
This paper provides a comprehensive review of the modeling methods for radiant floor cooling systems. It discusses the different modeling approaches, including analytical, numerical, and semi-analytical methods, and their applicability in various contexts. The paper also highlights the importance of considering heat transfer mechanisms, boundary conditions, and validation in modeling RFCS. Overall, the paper contributes to the understanding of RFCS modeling and provides valuable insights for researchers and practitioners in the field.
1) The paper provides a thorough review of the literature on modeling methods for radiant floor cooling systems. It covers a wide range of methods and presents their strengths and limitations.
2) The paper highlights the importance of considering different heat transfer mechanisms, such as conduction, convection, and radiation, in modeling RFCS. It discusses the impact of these mechanisms on the performance of the system.
3) The paper emphasizes the need for validation of the models and discusses different validation approaches used in the literature. It highlights the importance of experimental data in validating the models and improving their accuracy.
4) The paper does not provide specific implementation details for reproducing the study. It would be helpful to provide more information on the datasets, code, or software used in the reviewed papers.
5) The paper does not include a comparative analysis of the different modeling methods or a discussion of their advantages and disadvantages. It would be beneficial to have a more in-depth analysis of the strengths and weaknesses of each method.
6) The paper lacks discussions on the limitations of the reviewed models and potential areas for future research. It would be valuable to provide insights into the gaps in the literature and suggest directions for future studies.
7) Can you provide more information on the datasets, code, or software used in the reviewed papers for modeling RFCS? This information would be helpful for readers who want to reproduce the study or explore further in this field.
8) Could you provide a comparative analysis of the different modeling methods discussed in the paper? It would be beneficial to have a more in-depth discussion of the strengths and weaknesses of each method and their applicability in various contexts.
9) Can you discuss the limitations of the reviewed models and potential areas for future research? It would be valuable to provide insights into the gaps in the literature and suggest directions for future studies.
The paper provides a comprehensive review of the modeling methods for radiant floor cooling systems. It covers a wide range of methods and discusses their strengths and limitations. However, the paper lacks specific implementation details, comparative analysis of the methods, and discussions on the limitations and future research directions.
Author Response
Dear Reviewer 2,
We would like to thank you very much for your time and valuable feedback. Your suggestions and criticisms have led us to significantly improve the quality of the paper, which we believe is now more scientifically sound and consistent with our original intent.
In addition to the issues you highlighted, we are pleased to note your positive comments about the paper. Thank you for recognizing the comprehensive nature of the review and our efforts to address heat transfer mechanisms within the models. Your recognition of the importance of validation and experimental studies is encouraging, and we are pleased that the overall contribution of the paper to RFCS modeling was apparent to you.
We now turn our attention to your specific criticisms, which, as you said, can be summarized in the following three points: the lack of specific implementation details, the lack of a comparative analysis of modeling methods, and the lack of discussion of model limitations and possible future directions. We will address each comment in turn and revise the paper accordingly.
- Lack of specific implementation details
In response to some of the questions raised by Reviewer 1, we had the opportunity to improve the description of the modeling methods presented in Sections 3 and 4. In fact, the discussion of the methods has been enriched with quantitative data, examples, and more details on the results of the studies. Your suggestions will allow us to further expand the description by including information on the datasets, code, or software used, where available. Therefore, in the aforementioned sections, you will find several changes and additions that have been inserted to fill this gap. In addition, a specific paragraph has been added on page 6, from line 214 to line 217 (see text with highlighted changes), to provide a summary of the codes used by the models. In fact, most of the proposed modeling methods use in-house software developed by the research groups specifically for scientific purposes.
- Lack of a comparative analysis of modeling methods
We now acknowledge this as a major gap in the paper, as the other reviewer also raised a similar criticism. We will give the same response to both of you.
The review paper analyzes a total of 28 modeling methods for radiant floor cooling systems. The methods were divided into two main categories, and the specific features of each model were highlighted and summarized in tables and Sankey diagrams.
Each model has its own unique features which may become advantages or disadvantages depending on the specific application for which it is intended.
However, in order to provide a comparative analysis between the different methods, a summary paragraph has been added to Section 3, page 12, lines 453-468, highlighting general considerations about the strengths and weaknesses of each class of methods.
- Lack of discussions of model limitations and potential future directions
A similar gap was also mentioned by Reviewer 1. As we have tried to point out in the text, the main gap in the current literature on the subject is the lack of comprehensive yet easily characterizable models that could be effectively used in widespread application. Such models should somehow take into account all relevant phenomena and effects involved in the operation of RFCS. The main omissions or oversimplifications of the available studies have been identified as the lack schematization of the presence of furnishings in the buildings and the superficial treatment of the convective exchange between the floor surface and the ambient air. Also, further modeling efforts should include and take into account the influence of solar radiation, which has been neglected in some of the reviewed models.
These gaps have now been more fully addressed in the text by the addition of the following paragraphs: on page 22 from line 803, on page 23 from line 883, and on page 25 from lines 977-982 and lines 990-994. The latter provide specific suggestions on how to address these future directions.
In light of the adjustments we have made to address the feedback provided in your review, we now believe that our paper is more scientifically rigorous. Indeed, your comments have been helpful in completing and refining the text to better present the findings of our review paper.
Round 2
Reviewer 1 Report
Firstly, I would like to express my appreciation for the modifications and revisions made by the authors to this paper. The authors have diligently addressed the suggestions provided in the initial review, and through their efforts, the content and structure of this paper have been significantly enhanced, resulting in a marked improvement in its quality.
Within the realm of the authors' revisions, they not only augmented and modified the content in response to the proposed revisions but also introduced additional material to enhance the coherence of the logical flow within the article. In terms of linguistic expression, the authors further refined the sentence structures and vocabulary choices in the paper, resulting in a smoother and more comprehensible text.
In summation, I am of the opinion that the authors, building upon the foundation of the initial review's suggestions, have made thorough revisions and improvements to the paper, achieving a level of scholarly content and linguistic articulation worthy of inclusion in this journal. Based on the current quality of the revised manuscript, I recommend its acceptance for publication.
No
Reviewer 2 Report
Continuously following authors research.
