Experimental Assessment of the Thermal Influence of a Continuous Living Wall in a Subtropical Climate in Brazil

Round 1

Reviewer 1 Report

Main impression:

The topic of the article is interesting and the obtained results are worthy of publication. The abstract is well presented and clearly outline the study carried out and the main conclusion. Keywords are sufficient to cover all the research work. The introduction is consistent and clearly sets out the relevance of the topic. The experimental programme is well described and the main constraints of the study were mentioned and framed. The results are well presented and the discussion is consistent. Finally, conclusions partially reflect the obtained results and must be improved. Some minor flaws and inaccuracies were detected along the article, especially from a formal point of view, which require the attention of the authors. Therefore, the article can be accepted after a minor revision. A list of comments/suggestions to allow the authors to improve the quality of the manuscript is presented below, following the order of appearance in the text.

 

Concerning the “Abstract”:

(1) Line 16: Explain what means “Cfa climate”, because the reader may not be familiar with this classification. Add, for example: “subtropical climate, with hot summer (Cfa)”.

 

Concerning the “Introduction”:

(2) Line 41: Regardless of the citation style used or admitted by this journal, citations are confusing in the text: e.g. “(PERINI et al., 2013; BESIR; CUCE, 2018)”. It should be “(Perini et al., 2013; Besir and Cuce, 2018)”. The same happen in line 43: “(WONG et al., 2009; KONTOLEON; EUMORFOPOULOU, 2010; PAN et al., 2018)”. It should be “(Wong et al., 2009; Kontoleon and Eumorfopoulou, 2010; Pan et al., 2018)”. Preferably, do not use capital letters for the author's last name, in order to maintain uniformity with the citations made throughout the article, as for example in lines 60 and 61: “… investigated by Wong et al. (2010), Chen et al. (2013), Tan et al. (2014) and Charoenkit and Yiemwattana (2017) in tropical climates…”. Please revise accordingly to MDPI Reference List and Citations Style Guide and maintain uniformity throughout the article.

 

Concerning the “Material and Methods”:

(3) Line 112, Figure 2: Identify the images by inserting (A) and (B). Additionally, it appears that the source of these figures was placed in Figure 3 by mistake.

(4) Line 116, Figure 3: Review the sources and identify the images by inserting (A) and (B) in the sample plots. Additionally, Figure 3 identifies with the letter "N" a northern façade, but compared with Figure 2, everything indicates that it is an eastern façade. Please review and clarify accordingly.

(5) Line 129, Figure 4: Correct the image to match the numbering to the different layers.

(6) Line 150, Figure 6: Identify the images by inserting (A), (B) and (C).

(7) Line 194, Table 1: As decimal separator in numbers, you should use a dot instead of a comma, for example: “0.2” instead of “0,2”. Additionally, separate the number from the unit, except for percentage, as for example: “0.5 °C” instead of “0,5°C”. When specifying the range, it is preferably to use “- 40 °C to 199.9 °C” instead of “-40°C - 199.9°C”. Please revise the whole article accordingly, as there are many situations similar to those reported here, as in Table 2, Table 4, Table 5 and Table 6. Review the numbering of the tables, because in the item “Results and Discussion” Table 3 is missing.

(8) Line 202: It should be: “…kept 4 m away…”, instead of “…kept 4m away…”. Revise the whole text accordingly.

 

Concerning the “Results and Discussion”:

(9) Lines 227, 239, 264, 265, 329, Table 6, among others: It is suggested that the way of presenting the hours in the text be standardised with that used in the graphs, in order to avoid misinterpretations. Revise the whole text accordingly.

(10) Line 298: It should be: “… (10.6 ºC).”, instead of “… (10.6 ºC).”.

(11) Line 317: It should be: “… range of 20 °C to 25 °C …”, instead of “… range of 20 °C - 25 °C …”. Revise the whole text accordingly.

(12) Line 332: It should be: “… peaks of up to 6 h …”, instead of “… peaks of up to 06h …”. Revise the whole text accordingly.

 

Concerning the “Conclusion”:

(13) Line 466: It should be: “… up to 1 hour for internal surface …”, instead of “… 1 hour for internal surface …”.

(14) Line 476 to 477: It is mentioned: “The union of shading and insulation mechanisms contributed to keeping the surface temperatures of the entire system lower than those of the control plot.”. It should be added that this occurs in the presence of direct solar radiation on the façade. All the conclusions should be put into context, making it clear that they were obtained from data recorded over a short period of time (in the presence of solar radiation) and do not represent the entire measurement period (day and night).

 

Concerning the “References”:

(15) The names of the authors in the references are incomplete. For example, in "ALVARES, C.A. et al.", the names of the remaining authors should be included. Review the entire reference list accordingly, as there are other identical cases.

Author Response

Dear Editor and Reviewer,

We appreciate all contribution to improving the submitted article. The current text contains the review with all the reviewers' suggestions, but we specifically highlight those punctuated by reviewer 1. We emphasize that we had to add table 3 for a better discussion of the results of this work with the literature.

Reviewer 1:

Concerning the “Abstract”:

(1) Line 16: Explain what means “Cfa climate”, because the reader may not be familiar with this classification. Add, for example: “subtropical climate, with hot summer (Cfa)”.

The explanation of the term "Cfa climate" has been added to the abstract. (Line 15)

Concerning the “Introduction”:

(2) Line 41: Regardless of the citation style used or admitted by this journal, citations are confusing in the text: e.g. “(PERINI et al., 2013; BESIR; CUCE, 2018)”. It should be “(Perini et al., 2013; Besir and Cuce, 2018)”. The same happen in line 43: “(WONG et al., 2009; KONTOLEON; EUMORFOPOULOU, 2010; PAN et al., 2018)”. It should be “(Wong et al., 2009; Kontoleon and Eumorfopoulou, 2010; Pan et al., 2018)”. Preferably, do not use capital letters for the author's last name, in order to maintain uniformity with the citations made throughout the article, as for example in lines 60 and 61: “… investigated by Wong et al. (2010), Chen et al. (2013), Tan et al. (2014) and Charoenkit and Yiemwattana (2017) in tropical climates…”. Please revise accordingly to MDPI Reference List and Citations Style Guide and maintain uniformity throughout the article.

All citations were standardized as suggested and with no capital letters. (Line 33)

Concerning the “Material and Methods”:

(3) Line 112, Figure 2: Identify the images by inserting (A) and (B). Additionally, it appears that the source of these figures was placed in Figure 3 by mistake.

The figure was reviewed and identified. The captions were also correctly placed in their respective figures. (Line 139)

(4) Line 116, Figure 3: Review the sources and identify the images by inserting (A) and (B) in the sample plots. Additionally, Figure 3 identifies with the letter "N" a northern façade, but compared with Figure 2, everything indicates that it is an eastern façade. Please review and clarify accordingly.

The figure was reviewed and identified. The captions were also correctly placed in their respective figures. (Line 143)

(5) Line 129, Figure 4: Correct the image to match the numbering to the different layers.

The numbers were placed on the correct layer. (Line 156)

(6) Line 150, Figure 6: Identify the images by inserting (A), (B) and (C).

The images were identified using the captions(A), (B) and (C). (Line 178)

(7) Line 194, Table 1: As decimal separator in numbers, you should use a dot instead of a comma, for example: “0.2” instead of “0,2”. Additionally, separate the number from the unit, except for percentage, as for example: “0.5 °C” instead of “0,5°C”. When specifying the range, it is preferably to use “- 40 °C to 199.9 °C” instead of “-40°C - 199.9°C”. Please revise the whole article accordingly, as there are many situations similar to those reported here, as in Table 2, Table 4, Table 5 and Table 6. Review the numbering of the tables, because in the item “Results and Discussion” Table 3 is missing.

The entire text has been revised considering the suggestions. Commas have been replaced by periods as the decimal separator. All ranges were written using "to" and the units were separated from the numbers. In addition, the error of continuity of the table identification number was corrected, adding table 3 to improve the discussion of the results with the literature. (Line 221, 281, 295, 346, 367, 385)

(8) Line 202: It should be: “…kept 4 m away…”, instead of “…kept 4m away…”. Revise the whole text accordingly.

All text has been revised and units have been separated from numbers. (Line 230)

Concerning the “Results and Discussion”:

(9) Lines 227, 239, 264, 265, 329, Table 6, among others: It is suggested that the way of presenting the hours in the text be standardized with that used in the graphs, in order to avoid misinterpretations. Revise the whole text accordingly.

The hours in the text and tables were standardized with the format used in the graphs. (Lines 255, 256, 262, 263…)

(10) Line 298: It should be: “… (10.6 ºC).”, instead of “… (10.6 ºC).”.

Rewritten text (line 278)

(11) Line 317: It should be: “… range of 20 °C to 25 °C …”, instead of “… range of 20 °C - 25 °C …”. Revise the whole text accordingly.

All data ranges present in the text were revised in writing as suggested, using “to”. (Line 360)

(12) Line 332: It should be: “… peaks of up to 6 h …”, instead of “… peaks of up to 06h …”. Revise the whole text accordingly.

All hours were revised as suggested and 0 was removed when the text referred to the hourly range from 1 to 9. (Line 375)

Concerning the “Conclusion”:

(13) Line 466: It should be: “… up to 1 hour for internal surface …”, instead of “… 1 hour for internal surface …”.

Suggestion accepted (Line 525).

(14) Line 476 to 477: It is mentioned: “The union of shading and insulation mechanisms contributed to keeping the surface temperatures of the entire system lower than those of the control plot.”. It should be added that this occurs in the presence of direct solar radiation on the façade. All the conclusions should be put into context, making it clear that they were obtained from data recorded over a short period of time (in the presence of solar radiation) and do not represent the entire measurement period (day and night).

The conclusions were placed in the context of the monitoring period in the lines 517 and 518.

Concerning the “References”:

(15) The names of the authors in the references are incomplete. For example, in "ALVARES, C.A. et al.", the names of the remaining authors should be included. Review the entire reference list accordingly, as there are other identical cases.

All references have been revised as suggested and all author names have been included (Line 560).

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper presents a experimental study for the thermal influence of a living wall. The topic is interesting and relevant to the journal. The paper is well organized and written. However, I would suggest the following comments to be addressed before it can be published.

My major concern is that novelty of this study. This should be elaborated in the introduction section. All statement should be precise. What is short in existing research? How does this paper fill the gap? Can the presented case study support the claim?

As stated in the last paragraph in the introduction section, this paper is new because it studies a living wall of continuous model under the hot and humid weather conditions. Has the continuous model been investigated by existing research? If yes, how this paper differs from them. Is there any other research studying similar weather conditions? Since this study only tested three summer days, is the pattern of the weather conditions during the three days special against that in other research? For example, Wong et al., 2010 studied different seasons, and the summer day they studied may have a similar pattern as this study. Then, it becomes tricky to claim the novelty of this study lies in a different climate condition against existing research.

As an experimental study, the comprehensiveness of the tested case seems weak. It only studied a simple case with limited numbers of models for three days. Some temperatures were monitored. Compared to Wong et al., 2010 and other existing research, what new knowledge/message is conveyed from the experiment conducted in this paper? How the conclusions of this paper can be generalized and help others for their applications?

Why the temperatures at night were not monitored? Any comments about the slow heat dissipation during the night in summer with the living wall? What is the impact on the cooling demands? How about the heating scenario? What is the impact on the heating demands?

Author Response

Dear Editor and Reviewer,

We appreciate all contribution to improving the submitted article. The current text contains the review with all the reviewers' suggestions, but we specifically highlight those punctuated by reviewer2. We emphasize that we had to add table 3 for a better discussion of the results of this work with the literature.

Reviewer 2:

Question- My major concern is that novelty of this study. This should be elaborated in the introduction section. All statement should be precise. What is short in existing research? How does this paper fill the gap? Can the presented case study support the claim? As stated in the last paragraph in the introduction section, this paper is new because it studies a living wall of continuous model under the hot and humid weather conditions. Has the continuous model been investigated by existing research? If yes, how this paper differs from them. Is there any other research studying similar weather conditions?

Answer- The entire introduction has been revised.

Regarding the first question, in Brazil there are only 2 works (dissertations) besides ours and only one in summer, but with different climate and facade orientations. Furthermore, we further highlight the gaps and needs of this type of work as 1- low climate diversity; 2- the lack of studies with continuous living walls; 3- the lack of studies in summer and with Eastern orientation.

In this scenario, the objectives of this work seek to fill all the gaps pointed out in the literature review and differentiate from other works by investigating the thermal influence of a continuous living wall, in the summer of a subtropical climate, on an East facade and with an experimental approach with a garden. and real building.

In the same sense, this work carried out a monitoring that allows its comparison with the others, explaining in detail in its methodology from the construction of the garden with its materials and species to the equipment, variables monitored according to the literature and statistical analysis of the results. (Lines 30 to115).

Q- Since this study only tested three summer days, is the pattern of the weather conditions during the three days special against that in other research?For example, Wong et al., 2010 studied different seasons, and the summer day they studied may have a similar pattern as this study. Then, it becomes tricky to claim the novelty of this study lies in a different climate condition against existing research.

A- Weather conditions vary between different climates and may show similarities. However, the climates are different from each other, as highlighted in the literature and the monitoring days were representative for the climatic conditions of the city of Bauru and the subtropical climate in Brazil, according to data from the Bauru Meteorology Center-IPMET reported in the Methodology. All microclimatic variables remained within the historical range, with clear sky days and high solar radiation. (Lines 121 to 125, 199 to 203).

In addition, Cfa climate characteristics represent a large region in Brazil and investigating the thermal behavior of living walls under these conditions fills an information gap in a climate with large daily thermal variation and in a country where studies on urban green infrastructure applied to thermal issue are still incipient.

The novelty of this study is highlighted in its general and specific objective, from the filling of gaps such as: the subtropical climate, the east orientation, the use of continuous living wall and in the characterization of the behavior of surface temperatures along the "garden- protected wall" (lines 107 to115).

Q- As an experimental study, the comprehensiveness of the tested case seems weak. It only studied a simple case with limited numbers of models for three days. Some temperatures were monitored. Compared to Wong et al., 2010 and other existing research, what new knowledge/message is conveyed from the experiment conducted in this paper? How the conclusions of this paper can be generalized and help others for their applications?

A- In order to compare the results of this work with others in the literature, such as Wong et al. (2010), table 3 was added and the discussion of the results was expanded. (Lines 284 to 331). The results of this work for internal surface temperature are unprecedented for the continuous living wall (as shown in table 3) and its behavior (from 8:00 to 17:45), together with the experimental condition (single facade of a real building), demonstrates that for subtropical climate the living wall has a significant influence on the reduction of internal temperatures and can improve the thermal efficiency of the building during the day.

In addition, this work demonstrates data that was not identified in any other of the literature review. For the summer in a subtropical climate, vegetation contributes (through shading the external surface of the garden) with about 10% of the average reduction in external surface temperature peaks. (Lines 451 to 456). All conclusions were revised to clarify te contributions of this study. (Lines 508 to 553).

Q- Why the temperatures at night were not monitored?

A- Justified on the lines 214 to 220.

Q- Any comments about the slow heat dissipation during the night in summer with the living wall?

A- Throughout the development of the work, input and output energy analyzes were considered and included in the research project. However, due to the lack of funding for the purchase of accurate equipment for thisspecific monitoring, unfortunately we were unable to proceed with these analyses.

Thus, we seek to discuss this energy input and output through variations and reductions in external and, mainly, internal surface temperatures as well as the cavity air temperature, which indicate the direction and temporal behavior of the heat flow. Heat dissipation was discussed as well. (Lines 309 to 331, 417 to420, 422 to 426, 473 to 478, 488 to 495).

Q-What is the impact on the cooling demands? How about the heating scenario? What is the impact on the heating demands?

A- In Brazil, there is no demand for heating for subtropical climate, only for active cooling. However, as the building is used seasonally (only for exhibitions of final graduation works), this work was carried out in a period without use and, therefore, with the air conditioning turned off.

This decision aims to understand the thermal behavior of surface temperatures in a real situation, without the influence of active cooling or internal anthropogenic heat production. Future work is being carried out to discuss the demand for cooling.

Reviewer 3 Report

The authors reported the study titled “Experimental assessment of the thermal influence of a continuous living wall in “hot and humid” weather conditions in Brazil”. This work investigates experiments on the thermal influence of a continuous living wall on the surface temperatures of an east façade. The key objective of the study is to access the thermal influence of a continuous living wall in hot and humid weather conditions of Brazil. In this regard, temperature measurement campaigns were carried out on 18 external and internal surfaces of the garden-protected plot and control plot system. The topic original and relevant in the field, however, study do not address in-depth research gap. Overall, the study can be improved with the following revisions:

-    Correct the title, there is a typo error.
-    The English of the paper can be improved. For example, first sentence of the introduction section is too long and can be divided into 2-3 sentences for better understanding. Similarly, please go through the paper from start to finish.
-    Research gap is not clear and not linked to the research objectives.
-    Cfa should be mentioned as humid subtropical climate in abstract at least for general readers.
-    There is need to add detail regarding the methodology in abstract.
-    There is no record of uncertainty in data as well as specification of the instruments used.
-    Add more details regarding the instrumentation needs.
-    More numerical and qualitative findings can be added in the abstract to give a quick overview for the readers regarding the outcome of this experimental work.
-    In results and discussion, cross-discuss the results with the published papers to strengthen the need and significance of this study.
-    Try to extend the analyses part. These are only results.
-    All the figures in results and discussion sections are mainly related to the temperature difference between different layers. Authors can plan to increase the analyses in terms of energy saving or cost analyses of energy saving. In addition, input energy and output energy (saving) analyses can be performed in order to add more science and strength in the article findings.
-    The graphics of the figure can be improved special in results and discussion section (temperature variation figures).
-    Fig 10-12 can be a single figure with (a), (b), and (c). Fig 13-15 can be a single figure with (a), (b), and (c). Fig 16-18 can be a single figure with (a), (b), and (c).
-    After Table 2, there is Table 4. Where is Table 3?
-    The conclusions are good and informative for the reader. The conclusions are consistent with the evidence and arguments however most of the part is obvious.
-    Try to cite recent studies preferably from this journal in the discussion section in order to justify the relevance of the journal as well as the research gap.

Author Response

Dear Editor and Reviewer,

We appreciate all contribution to improving the submitted article. The current text contains the review with all the reviewers' suggestions, but we specifically highlight those punctuated by reviewer3. We emphasize that we had to add table 3 for a better discussion of the results of this work with the literature.

Reviewer 3:

Question- Correct the title, there is a typo error.

Answer- The title was modified. (Lines 1 to 2)

Q- The English of the paper can be improved. For example, first sentence of the introduction section is too long and can be divided into 2-3 sentences for better understanding. Similarly, please go through the paper from start to finish.

A- All text has been revised for English improvements. Paragraphs that were long were broken up and new ones were written more directly.

Q- Research gap is not clear and not linked to the research objectives.

A-The introduction was rewritten from the literature review to highlight the research gaps and the objectives were better specified and linked to the gaps. (Lines 56 to 115.)

Q- Cfa should be mentioned as humid subtropical climate in abstract at least for general readers.

A- Suggestion accepted (Line 15)

Q- There is need to add detail regarding the methodology in abstract.

Details have been added in abstract (Lines 14 to 20)

Q- More numerical and qualitative findings can be added in the abstract to give a quick overview for the readers regarding the outcome of this experimental work.

A- Suggestion accepted (Lines 20 to 25)

Q- There is no record of uncertainty in data as well as specification of the instruments used.And Q- Add more details regarding the instrumentation needs

A- Table 1 specifies all instruments. (Lines 210 and 211, 221)

Q- In results and discussion, cross-discuss the results with the published papers to strengthen the need and significance of this study. Try to extend the analyses part. These are only results.

Table 3 was added for better comparison between studies and the analysis and discussion of results was expanded.Unpublished results were highlighted. (Lines 284 to 345, 389 to 399, 451 to 456)

Q- All the figures in results and discussion sections are mainly related to the temperature difference between different layers. Authors can plan to increase the analyses in terms of energy saving or cost analyses of energy saving. In addition, input energy and output energy (saving) analyses can be performed in order to add more science and strength in the article findings.

A- Throughout the development of the work, input and output energy analyzes were considered and included in the research project. However, due to the lack of funding for the purchase of accurate equipment for thisspecific monitoring, unfortunately we were unable to proceed with these analyses.

Thus, we seek to discuss this energy input and output through variations and reductions in external and, mainly, internal surface temperatures as well as the cavity air temperature, which indicate the direction and temporal behavior of the heat flow  (Lines 309 to 331, 417 to420, 422 to 426, 473 to 478, 488 to 495).

Q- The graphics of the figure can be improved special in results and discussion section (temperature variation figures).Fig 10-12 can be a single figure with (a), (b), and (c). Fig 13-15 can be a single figure with (a), (b), and (c). Fig 16-18 can be a single figure with (a), (b), and (c).

Graphs have been revised and curves have been treated for line thickness and markers for readability.As well, Figures 10-12, 13-15 and 16-18 were unified transforms with graphs (a), (b) and (c). (Lines 273, 411, 483)

Q- After Table 2, there is Table 4. Where is Table 3?

Table 3 has been inserted. (Line 295)

Q-The conclusions are good and informative for the reader. The conclusions are consistent with the evidence and arguments however most of the part is obvious.

A- The conclusions were revised and rewritten in order to clarify the contribution of the work. (Lines 508 to 553)

Q- Try to cite recent studies preferably from this journal in the discussion section in order to justify the relevance of the journal as well as the research gap.

Three recent studies (Moghaddam et al., 2020; Pan et al., 2018; Ruiz-Valero et al.,2022) were included in the work, but only the study by Moghaddam et al. (2020) is from Sustainability journal. (Lines 62, 90, 95).

A search was carried out in this journal's database with the following keywords: "living wall", "green wall" and "vertical garden" combined with "thermal performance" and "thermal behavior" and no experimental work was found on the thermal influence of living walls.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

This paper has been improved significantly. I don't have further comments.