Indoor Air Quality Improvement by Simple Ventilated Practice and Sansevieria Trifasciata

Round 1

Reviewer 1 Report

The objective of this paper is to propose an improving IAQ method with low energy consumption. I consider that this paper needs some corrections before being accepted for publication. Please consider the following comments:

In the section 2. Experiments, an assessment of the envelope air permeability of the room should be referred to. The air conditioning system shall be described. In the section 2.5 Numerical study, more detail about the characteristics of the mesh should be done (e.g., grid refinement). Did the researchers made a grid refinement study? Details of the study shall be presented. A simulation for a validation case must be presented. In the section 3.1 Results of monthly monitoring data, the outdoor reference conditions during indoor measurements shall be presented. The weather conditions, temperature and wind velocity and direction should be presented. The figure 5 is only showing CO2 data. The subtitle shall be corrected. In the section 3.2 Results of simple ventilated practices for the improvement of IAQ the authors shall explain why is the concentration of CO2 is being reduced when the air conditioning is more time inactive. The sentence “The average mean age of the air in Figure. 8a and 8b are 747 s and 164 s respectively. Thus, the efficiency of the ventilation using only a 39 watt ceiling fan, from which the volume of air blown is 30 m 3 /min, is improved by approximately four times.” shall be revised. The ceiling fan is mixing the air; it is not ventilating.

Author Response

No.	Comment	Correction
1	Experiments, an assessment of the envelope air permeability of the room should be referred to.	2.3 and 3.3 added an assessment of infiltration rate calculation and result (line 136-145, 329-332)
2	The air conditioning system shall be described.	2.1 described the air conditioning system (line 104-107)
3	In the section 2.5 Numerical study, more detail about the characteristics of the mesh should be done (e.g., grid refinement). Did the researchers made a grid refinement study? Details of the study shall be presented. A simulation for a validation case must be presented.	2.5 the detail of mesh characteristics has been added. Validation of the program is presented in many research that has been used. (line 168-172)
4	In the section 3.1 Results of monthly monitoring data, the outdoor reference conditions during indoor measurements shall be presented. The weather conditions, temperature and wind velocity and direction should be presented. The figure 5 is only showing CO2 data. The subtitle shall be corrected.	3.1 Outdoor climate is added and figure 5 subtitle has been corrected (line 235)
5	In the section 3.2 Results of simple ventilated practices for the improvement of IAQ the authors shall explain why is the concentration of CO2 is being reduced when the air conditioning is more time inactive.	3.2 The reason is explained (line 279-283)
6	The sentence “The average mean age of the air in Figure. 8a and 8b are 747 s and 164 s respectively. Thus, the efficiency of the ventilation using only a 39 watt ceiling fan, from which the volume of air blown is 30 m 3 /min, is improved by approximately four times.” shall be revised. The ceiling fan is mixing the air; it is not ventilating.	3.4 the sentence is revised (line 359)

Author Response File: Author Response.docx

Reviewer 2 Report

Dear authors,

I'm sharing with you the whole review in the attached file (in pdf).

This manuscript proposes a simple ventilated practice and placing many indoor plants to improve occupant's comfort in indoor offices (Valaya Alongkorn Rajabhat University).   You have investigated IAQ conditions in an office which is located in Thailand. The problem presented in the paper is very interesting, especially since it involves tropical region issues. The materials, the monitoring procedure, as well as simulations are standard and clear, without any original contribution. However, the experimental condition «deserves» special attention. Some results are well explained and commented on, but the motivations for this study need to be made clearer and statistical analysis needs some improvements. For instance, the real relative contributions of ventilation and plants (to reduce C O 2) are not clear. The reason for my misunderstanding is that results (plant vs ventilation contribution) of a paper base on the experimental procedure, are inconclusive.   One of my major concerns is about false citations: these are accredited to an author or a paper but when one searches for the citations in original work, I can find such citation neither as text nor as an idea. For example, in the first sentence, the first paragraph in the introduction (line 33) I didn't find the information in reference 1 ( https://climate.nasa.gov/news/2575/march-2017-was-second-warmest-march-on-record/ . Besides, there is nothing about mother-in-law's tongue in that reference (1) which is mentioned in lines 357-358. Also, I wonder why the authors have not referenced the major works in this field of research (check below)?

For these main points, this paper could be published in a major revised form taking into account the whole suggestions in the attached file.

Best regards

Reviewer

Comments for author File: Comments.pdf

Author Response

No.	Comment	Correction
1	the experimental condition «deserves» special attention.	2.3 the experimental condition is as usual (line 124-126)
2	Some results are well explained and commented on, but the motivations for this study need to be made clearer and statistical analysis needs some improvements. For instance, the real relative contributions of ventilation and plants (to reduce C O 2) are not clear.	2.3, 3.2, 3.3 Statistical analysis is analyzed by One-Way ANOVA (line 129-130, 293-295, 328-332)
3	Results (plant vs ventilation contribution) of a paper base on the experimental procedure, are inconclusive.	3.3 Statistical analysis is analyzed by One-Way ANOVA (Line 330-332)
4	One of my major concerns is about false citations: these are accredited to an author or a paper but when one searches for the citations in original work, I can find such citation neither as text nor as an idea. For example, in the first sentence, the first paragraph in the introduction (line 33) I didn't find the information in reference 1 ( https://climate.nasa.gov/news/2575/march-2017-was-second-warmest-march-on-record/ . there is nothing about mother-in-law's tongue in that reference (1) which is mentioned in lines 357-358.	1. and reference [1,2] the first sentence has been revised by new reference (line 33 and 432-435)

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Since the ventilation of the room is just carried out by natural means, it should be made clear what are the outside weather conditions along whole testing period. Thus, a figure with the outdoor temperature, wind velocity and direction shall be added in order to show the impact of the natural actions on the ventilation of the room and, therefore, the impact on the indoor pollutant concentration.

Author Response

Dear Reviewer,

Comment	Revision
Since the ventilation of the room is just carried out by natural means, it should be made clear what are the outside weather conditions along whole testing period. Thus, a figure with the outdoor temperature, wind velocity and direction shall be added in order to show the impact of the natural actions on the ventilation of the room and, therefore, the impact on the indoor pollutant concentration.	We added ambient air quality by including Figure 7 Diurnal temperature in the ambient air and in the room during experiments and Figure 8 Diurnal relative humidity in the ambient air and in the room during experiments were added and included some information in lines 317-322.

Author Response File: Author Response.docx

Reviewer 2 Report

Dear Authors,

I recently read this paper, analyzed it, and reached a conclusion. I spent a lot of time doing this review. However, many of my requests (in the attached file) were not taken into account in the last revision. I don't know why!

Here are my comments in my first review,

Major

1. There is no original contribution. We expect something that highlights the specificity of Thailand to reduce indoor air pollution. There could be more original observations and comparisons by including, if possible, other pollutants. This study is indoor comfort-oriented, while IAQ includes other several parameters and pollutants.
2. I send you many references that could be included in the manuscript. Please see the attached file!
3. The method and the experimental apparatus is quite standard and is appropriate for the study. For this reason, I don't think any additional experiments are necessary to validate the conclusions presented in the paper, because there are no expected surprise results. However, as mentioned above the experimental conditions should be explained clearly to highlight the relative contributions of both ventilation and plants for reducing C O 2.
4. Besides the previous comment, see lines 138-140. The study must provide all general information necessary to be able to carry out the importance of these plants. Other parameters could come into play (at the same time) for reducing CO2 such as ventilation ...
5. The objective is clearly defined in the sentences of the last paragraph of the introduction (lines 90–94). However, I do think that the motivations for this study need to be made clearer. In particular, the will to link (at all costs) comfort parameters, indoor plants to achieve lower energy consumption associated with reducing GHG emissions. If so, authors have to show the impact of using the proposed simple ventilation and mother-in-law’s tongue plants in the office on reducing GHG emissions. This should be done quantitatively. One way to show this connection would be to cite references (if possible) that demonstrate that using the ventilation or indoor plants impact GHG. Note that the greenhouse gas emissions level by Thailand is about 0.82% of the global worldwide emissions (in 2017).
6. The manuscript is well written and should be of great interest to the readers. However, statistical analysis would probably need to be included/revised. The paper in its form has an indirect message but has no specific recommendation.
7. All Figures have to be shown with a good «pixels» resolution and managing the y-axis scales for all plots. I suggest using Box Plot to highlight the time variability of each series.
   • In Figure 5 caption, there is no CO2 data showed in the Figure.
   • It seems to me that monthly variations (Figure 3-6) are not vital to the discussion presented in the paper. However, it is the daytime (diurnal) variations that are most important. I would suggest adding a diurnal variation in the discussion.
8. The article doesn't provide enough comparisons and insights of works in the same category. In addition, there should be a comparison of each important works. In this paper, mostly sequentially describes what has been done in each piece of work. This does not give readers vivid differences between these works.
9. Table 3. Outliers were identified; did you really find 70–76 °C values for maxim T ?. There could be an error in monitoring. Because the sensor is equipped with a temperature sensor, it should be shielded from direct sunlight. But there are no windows in the office.
10. Lines 110-111, period May 2017 to May 2018 does not cover March 2017. The latter was cited in the context of study: March 2017 was second warmest-march on record according to reference [1].
11. Lines 2013–216, In order to stress this argument, I suggest bettering show the diurnal variation of CO.
12. Lines 2017– 2018, it is said that «Further, while fluctuations can be observed between the minimum, maximum» Yes in some way, but the fluctuations can be highlighted only if use a suitable plot such as Box plot, or additional statistical tests.
13. Table 3. Outliers were identified; did you really find 70–76 °C values for maxim T ?. There could be an error in monitoring. Because the sensor is equipped with a temperature sensor, it should be shielded from direct sunlight. But there are no windows in the office.
14. Table 3. See maximum C O 2 vs number of plants. How can we explain the variations?
15. Line 290, «Thus the concentration of CO2 is not directly related to the number of plants placed in the room.» This needs extra analysis and requires further consideration. This is concerning the comment above.
16. The IAQ defined here include CO 2 and ventilation, this is very restrictive.
17. Line 286 «that plants reduce indoor CO2 concentrations [35]», please consider (some) suggested references above about this point.

Minors

1. Lines 63--67: The sentence should be reworded. Split it in two.
2. Line 72: put ref [11] at the end of the sentence.
3. Box plots for all Figures and re-scale y-axis.
4. Caption Fig 5. There is no CO2 data showed in the Figure.
5. Line 89: ASEAN should be defined before abbreviation.
6. Other minor misprints along with all the paper.

I am sorry to hammer away at you with the above. While the problem you consider is in the domain of attraction of "Atmosphere", you have to consider some technical issues.

Best regards, 

Comments for author File: Comments.pdf

Author Response

Dear Reviewer,

We have revised our manuscript. The detail is presented as followings:

Comment	Revision
lines 138-140. The study must provide all general information necessary to be able to carry out the importance of these plants. Other parameters could come into play (at the same time) for reducing CO2 such as ventilation	Information is added in lines 144-150
Reducing GHG emissions	GHG emission reduction is calculated for turning off air condition during 12:00 to 13:00 (Case 2) in lines 323-329
specific recommendation from statistical analysis	Lines 357-359
All Figures have to be shown with a good «pixels» resolution and managing the y-axis scales for all plots.	Every figures were changed followed the suggestion. However, Figure 3-6 present variation in each months so we added figure 7 and 8 for diurnal variation
comparisons and insights of works	We cited other works in lines 292-300
did you really find 70–76 °C values for maxim T ?.	This could be an error from there is no line in the table so I added line in table 3 for easily seen
Lines 110-111, period May 2017 to May 2018 does not cover March 2017. The latter was cited in the context of study: March 2017 was second warmest-march on record according to reference [1].	Revised the reference [1] already
Lines 2013–216, In order to stress this argument, I suggest bettering show the diurnal variation of CO	The CO was not changed so much. The results were between 0-1 ppm
Lines 2017– 2018 the fluctuations can be highlighted only if use a suitable plot such as Box plot, or additional statistical tests.	All figures were changed to be box plots
See maximum C O 2 vs number of plants. How can we explain the variations?	We explained in lines 338-343
Line 290, «Thus the concentration of CO2 is not directly related to the number of plants placed in the room.»	This is a conclusion from table 3 that has been explained in lines 338-343
Line 286 «that plants reduce indoor CO2 concentrations [35]», please consider (some) suggested references above about this point.	The reference is revised already
Lines 63--67: The sentence should be reworded. Split it in two. Line 72: put ref [11] at the end of the sentence. Box plots for all Figures and re-scale y-axis. Caption Fig 5. There is no CO2 data showed in the Figure. Line 89: ASEAN should be defined before abbreviation. Other minor misprints along with all the paper.	All are done. Thank you very much for your suggestions.

Author Response File: Author Response.docx

Round 3

Reviewer 1 Report

No more comments

Reviewer 2 Report

Dear,

This reviewed paper has a clear structure. Most of my suggestions were taken into account. Figures are good and there is a sufficient background chapter. The paper is pretty well written with many explanations. The paper can be accepted as is, with minor grammatical corrections. It is recommended that
a native English speaker conduct a minor revision.

I recommend publication and I'm looking forward to read your next paper based on the future work discussed in this paper.

I wish the author of the best.