A Study on the Status and Thermal Environment Improvement of Ceiling-Embedded Indoor Cooling and Heating Unit

Round 1

Reviewer 1 Report

This study focuses on thermal stratification in an indoor environment induced by a ceiling-embedded fan-coil unit, which reduces heating efficiency in cold seasons. The authors conducted temperature measurements on several heights and locations in a room as well as computational fluid model simulations to evaluate vertical temperature differences. By installing convectors and mini fans, this study evaluated the influences of convectors and mini fans on the indoor thermal stratification by the fan-coil units. The authors showed that air circulating systems like mini fans can effectively reduce vertical temperature difference and thermal stratification in a room, and further increase the thermal comfort of building users and the heating efficiency of the building. The result of this study implies that air circulation systems should be considered with the ceiling-embedded fan-coil units to improve indoor thermal comfort and energy consumption efficiency of heating system in winter, instead of more intensive heating of fan-coil units.

The finding of this study is good enough to be published in Sustainability. I’d like to recommend using a proofreading service to improve the readability of manuscript for the better readability. I believe that an English editing service will be helpful to enhance the quality of the manuscript further. I have a few  comments.

L53: Does the FCUs mean fan-coil units? Please specify it on L53 and in Figure 1.

L63: The authors didn’t provide the building overview in Figure 1. Please check it again.

L111: Please consider using “Results and Discussion” instead.

L134: The expression “The highest and the lowest temperatures” in the manuscript can be confused with daily maximum and minimum temperature. Please consider changing the wording.

L145: Please check the typo “plugss”

Table 2, 3, and 4: These figures (L198, 209, and 218) cannot be a table. In addition, there are other Tables 2 and 4 in the latter part of this manuscript. Please check the figures and tables carefully.

Author Response

Thanks for your comments. Your comment has been edited. 

L53: Changed (FCUs) to (FCUs: Fan Coil Units). And Figure 1 was also modified. 

L63: A building overview has been added to Table1. 

L111: Edited to “Results and Discussion”. 

L134: Corrected “The highest and the lowest temperatures” to “The highest and the lowest temperatures in experiment period”. 

L145: Fixed the typo. 

All tables and figures have been revised. 

Thank you very much for your comments. 

Reviewer 2 Report

Dear authors 

The article technically sounds really well. However, there are some concerns about details. Please consider all the comments below: 

1. There are many analyzes in the article. You should support them with a detailed discussion and managerial implications.
2. There is no literature review section. At least it would help if you had a better and well-detailed introduction. You should prove your ideas like this with more explanations in a multi-disciplinary journal such as Sustainability. 
3. PMV as a keyword is not supporting with any explanation. 
4. Please check the reference list. You need to do some modifications. 

Author Response

Thanks for your comments. Your comment has been edited. 

1,2. We have summarized the overall contents by reflecting your opinions.

3. I changed the keyword to the full name for PMV.

4. I checked the reference list

Thank You

Reviewer 3 Report

This work needs the following revisions:

- All the results are expressed in terms of temperature. In my opinion, there is a need for adding some results about heating/cooling loads in “kW”.

- There is a need to compare your results with others from the literature.

- You can enhance the mathematical formulation part of the paper by adding extra basic equations.

- More details about the CFD analysis are needed in order for making the results acceptable.

- Add a detailed nomenclature separated into sections.

- Try to improve the equality of the figures where it is needed (e.g. figure 16).

- More numerical results can be added in the conclusions section.

- Avoid merging many references together.

- Please avoid using abbreviations in the keywords.

- In the abstract, please add important numerical results. Also, provide an abstract of a single paragraph.

Author Response

Thanks for your comments. Your comment has been edited. 

1. The content of CFD analysis has been reorganized in the main text.
2. Numerical results have been added to the conclusion section.
3. I changed the keyword to the full name
4. I add important numerical results in the abstract

The overall content has been revised to reflect your opinions.

Thank your review

Round 2

Reviewer 3 Report

I am sorry but the authors did not reply to my comments properly and also they did not revise properly. Therefore, I have to reject it. The main reason for rection is the lack of results about the loads in kW.

Author Response

Thanks for the reviewer's comments and Suggestions.

Most of the reviewer's comments and Suggestions have been reflected and modified.However, it was not possible to correct the heating and cooling load because there was no measured data. Please understand. The revised part is marked in red in the carefully uploaded thesis.

The Manuscript has been uploaded for more details.

Thanks again for your comments and Suggestions.

Author Response File: Author Response.pdf