Improving Indoor Thermal Comfort and Air-Conditioning Management in Representative Primary Schools in Southern China

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This manuscript presents a well-structured and compelling study on indoor thermal comfort, with a clear focus and rigorous methodology. The topic is timely and relevant, especially in the context of growing concerns around indoor environmental quality. That said, I offer the following minor revisions and clarifying questions to further enhance the depth, clarity, and impact of the paper. 

 

1.  In the introduction, you mention that people spend a "substantial" amount of time indoors. Could you cite recent studies or statistics (e.g., WHO, EPA, or other regional data) to support this point? Quantifying this (e.g., "individuals spend approximately 80–90% of their time indoors") would provide stronger grounding.

2. When discussing the climatic diversity across China, please expand briefly on how building codes or standards reflect (or fail to reflect) this diversity. Are these standards centralized or region-specific? Do architectural practices vary across these zones? This would enrich your argument for a more nuanced thermal approach.

3. Improve Flow Between Paragraphs
   The transition between the sentence ending in “optimal comfort year-round [4][5]” and the next paragraph beginning with “According…” is a bit abrupt. Consider adding a linking sentence that signals a shift from general comfort considerations to the specific context or research question.

4. When referring to participants spending a “substantial portion of their active hours” in indoor environments, can you provide more specific data or a reference? A precise figure or range would enhance the credibility of the claim.

5. Your statement on the lack of specific standards for educational settings, and the resulting reliance on ISO-7730, EN15251, and ASHRAE 55, is crucial. I suggest moving this earlier in the introduction, as it defines the central issue and justifies the study’s relevance. It will also help differentiate this paper from other general thermal comfort studies.

6. Pre-Test Conditions
   Were students involved in any physical or mental activities prior to the experiment? Knowing if they were sitting, moving, or perhaps exposed to different thermal environments beforehand would help contextualize their thermal responses.

7. Clothing Description / Clo-Values
   What were students wearing during the measurements? Were they in uniforms or personal clothing? I cannot seem to find info in this paper about Clo-Value of the participants. 

8. Improve conclusion - You have introduced the issue of lack of building standards in educational settings, could you spend some words linking this issue with the results of your study?
9. A final remark. While I understand the study’s focus was not on neuro-architecture or broader environmental psychology, I encourage the authors to briefly acknowledge other sensory and environmental factors (e.g., color hue, acoustics, daylighting, prior nutrition) that can subtly influence thermal comfort perception. This could be done in the limitations or discussion section. For instance, take a look at section 5 of this paper https://www.sciencedirect.com/science/article/pii/S221462962100181X which discusses the multi-sensory and psychological nature of environmental comfort. A brief nod to this literature would demonstrate awareness of the wider context. 

 

Author Response

Dear Editors and Reviewer,

We would like to express our sincere gratitude for your valuable time, efforts, and constructive comments, which have significantly improved the clarity and overall quality of our manuscript originally titled “Enhancement of Indoor Thermal Conditions and Standardized Air-Conditioning Management in Representative Primary Educational Institutions in Southern China.”

In the revised version, we have updated the title to “Improving Indoor Thermal Comfort and Air-Conditioning Management in Representative Primary Schools in Southern China” to better reflect the study’s focus and improve readability.

Below, we provide a point-by-point response to each of the reviewers’ comments.  All revisions made to the manuscript have been clearly marked using track changes and addressed accordingly.

 

Comment 1: In the introduction, you mention that people spend a "substantial" amount of time indoors. Could you cite recent studies or statistics (e.g., WHO, EPA, or other regional data) to support this point? Quantifying this (e.g., "individuals spend approximately 80–90% of their time indoors") would provide stronger grounding.

Response: Thank you for the suggestion. We have revised Page 1, Paragraph 1 by adding the following: “According to NHAPS, people in developed countries spend approximately 87% of their time indoors.”

 

Comment 2: When discussing the climatic diversity across China, please expand briefly on how building codes or standards reflect (or fail to reflect) this diversity. Are these standards centralized or region-specific? Do architectural practices vary across these zones? This would enrich your argument for a more nuanced thermal approach.

Response: We added the following clarification to Page 1, Paragraph 2: “Building standards in China are partially centralized, with key performance indicators mandated nationally but design parameters adjusted by regional climate zones.”

 

Comment 3: Improve Flow Between Paragraphs

The transition between the sentence ending in “optimal comfort year-round [4][5]” and the next paragraph beginning with “According…” is a bit abrupt. Consider adding a linking sentence that signals a shift from general comfort considerations to the specific context or research question.

Response: A linking sentence has been added to Page 1, Paragraph 2: “In particular, educational buildings, which accommodate children and youth for long periods, present unique challenges for maintaining thermal comfort.”

 

 

Comment 4: When referring to participants spending a “substantial portion of their active hours” in indoor environments, can you provide more specific data or a reference? A precise figure or range would enhance the credibility of the claim.

Response: We have added on Page 2, Paragraph 2: “It is estimated that students spend over 30 hours per week inside classrooms.”

 

Comment 5: Your statement on the lack of specific standards for educational settings, and the resulting reliance on ISO-7730, EN15251, and ASHRAE 55, is crucial. I suggest moving this earlier in the introduction, as it defines the central issue and justifies the study’s relevance. It will also help differentiate this paper from other general thermal comfort studies.

Response: The final paragraph of the introduction has been updated to state: “Currently, thermal comfort guidelines tailored for educational settings remain limited, making it necessary to reference general public building standards.”

 

Comment 6: Pre-Test Conditions

Were students involved in any physical or mental activities prior to the experiment? Knowing if they were sitting, moving, or perhaps exposed to different thermal environments beforehand would help contextualize their thermal responses.

Response: We added the following in Section 2.2 (Page 4): “All thermal comfort surveys were conducted during regular class periods, ensuring students were in a rested, seated condition.”

 

Comment 7: Clothing Description / Clo-Values

What were students wearing during the measurements? Were they in uniforms or personal clothing? I cannot seem to find info in this paper about Clo-Value of the participants.

Response: We added on Page 5, Paragraph 1: “During the survey, students typically wore short-sleeve school uniforms, with an estimated Clo value of 0.5.”

 

Comment 8: Improve conclusion - You have introduced the issue of lack of building standards in educational settings, could you spend some words linking this issue with the results of your study?

Response: Thank you for this insightful suggestion. We have expanded the conclusion to more clearly link our findings with the policy gap. Specifically, the proposed 28°C setpoint, derived through regression analysis of student TSV data, demonstrates that empirical classroom observations can inform the formulation of practical thermal comfort standards tailored to primary schools. This reinforces the necessity of developing specific standards for educational buildings.

 

Comment 9: A final remark. While I understand the study’s focus was not on neuro-architecture or broader environmental psychology, I encourage the authors to briefly acknowledge other sensory and environmental factors (e.g., color hue, acoustics, daylighting, prior nutrition) that can subtly influence thermal comfort perception. This could be done in the limitations or discussion section.

Response: Thank you for your insightful suggestion. While our study primarily focuses on physical thermal parameters, we fully acknowledge the importance of sensory and psychological dimensions of environmental comfort. In the revised conclusion section, we have added a sentence highlighting the potential for future research to explore how students’ multisensory perceptions influence thermal comfort. We have also cited the recommended reference by Mazzone and Khosla (2021) to support this perspective.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

In this paper, the authors reported a new index, Thermal Sensation Vote (TSV), to observe the thermal comfort conditions for the classical room in two primary schools in a town in Southern China. The authors claimed that the TSV index could replace the PMV value and recommended a temperature setting of 28°C for thermal comfort.

The paper provided some helpful information. However, the sample location was too narrow. The location was limited to a town, not a county or broad region. The age of students was only included for students aged 12-13 years. The temperature and humidity ranged 26.4-29.5℃ and  49-87% RH, respectively. That was a local study, not a paper worth publishing in an international journal.

 

1. The regression technique was incorrect. The dependent variable was TSV, and the independent variable was PMV. However, the numeric values only included 0, 1, and 2. These values are fixed values and called categorical variables, and the PMV values are continuous. The TSV values cannot be served as the dependent values directly, as it violates the assumption of the regression. The regression method was incorrect, and the results from this statistical technique were meaningless. Please ask for help from the expert in statistics.
2. The statement “Numerous investigations conducted in both air-conditioned and naturally ventilated classrooms have revealed that students often report dissatisfaction with the thermal conditions present in these educational environments [29,30].” The literature cited this statement [29-30] and [31-32] were published in 1972, 1975, 2012, and 2014. Please supply some recent literature to support your statement.
3. In “Table 3. Information of two school classrooms.”, please explain the meaning of “ ventilation system was unavailable”.
4. In ”Table 6. Information on Measurement Instruments.”, please provide detailed information on the performance of this instrument, especially its accuracy, environmental effect, and calibration method.
5. Please perform more investigation about this research topic

, including more students of different ages, different locations, especially different provinces, and different seasons, including wide temperature and humidity ranges. 

After finishing more investigations, rewrite this paper.

6. Please answer this question: if the solar radiation were not considered in this empirical TSV equation, why use the black ball temperature?
7. No line numbers in this paper and the style of reference was not correct.

Author Response

Dear Editors and Reviewer,

We would like to express our sincere gratitude for your valuable time, efforts, and constructive comments, which have significantly improved the clarity and overall quality of our manuscript originally titled “Enhancement of Indoor Thermal Conditions and Standardized Air-Conditioning Management in Representative Primary Educational Institutions in Southern China.”

In the revised version, we have updated the title to “Improving Indoor Thermal Comfort and Air-Conditioning Management in Representative Primary Schools in Southern China” to better reflect the study’s focus and improve readability.

Below, we provide a point-by-point response to each of the reviewers’ comments.  All revisions made to the manuscript have been clearly marked using track changes and addressed accordingly.

 

Comment 1: The regression technique was incorrect. The dependent variable was TSV, and the independent variable was PMV. However, the numeric values only included 0, 1, and 2. These values are fixed values and called categorical variables, and the PMV values are continuous. The TSV values cannot be served as the dependent values directly, as it violates the assumption of the regression. The regression method was incorrect, and the results from this statistical technique were meaningless. Please ask for help from the expert in statistics.

Response: We appreciate the reviewer’s comment regarding the regression method. However, we would like to clarify that the primary objective of our study was to develop a regression model describing the relationship between TSV and environmental parameters (e.g., temperature and relative humidity), not between TSV and PMV. While TSV is categorical variables, it has been widely treated as a quasi-continuous variable in thermal comfort studies to enable practical regression modeling (e.g., Han et al., 2007, Building and Environment), particularly when the goal is to derive interpretable predictive relationships. In our study, PMV was not included as an input variable in the regression model; instead, it served as a comparative benchmark to evaluate the agreement and applicable range between the predicted thermal sensation and subjective votes. We have revised the manuscript to more clearly explain the roles of TSV and PMV in our analysis, and to avoid potential misunderstanding about the purpose of our regression model in Page15 and 16.

Comment 2: The statement “Numerous investigations conducted in both air-conditioned and naturally ventilated classrooms have revealed that students often report dissatisfaction with the thermal conditions present in these educational environments [29,30].” The literature cited this statement [29-30] and [31-32] were published in 1972, 1975, 2012, and 2014. Please supply some recent literature to support your statement.

Response: Thank you for pointing this out. We appreciate your suggestion regarding the use of more recent references. In response, we have updated the literature in the relevant paragraph and incorporated recent studies (Sun et al., 2023; Yi et al., 2023) to support the statement on dissatisfaction with thermal conditions in educational environments. These references reflect more current findings from school buildings in China and better align with the focus of our research.

Comment 3: In “Table 3. Information of two school classrooms.”, please explain the meaning of “ ventilation system was unavailable”.

Response: We have clarified this point in the manuscript: “The classrooms were not equipped with mechanical ventilation systems; airflow relied entirely on operable windows for natural ventilation.” in Page 4 and Table 3

 

Comment 4: In “Table 6. Information on Measurement Instruments.”, please provide detailed information on the performance of this instrument, especially its accuracy, environmental effect, and calibration method.

Response: We have added on Page 5 and Page 6: “All instruments were factory-calibrated and met the ISO 7726 standard. The measurement accuracy was ±0.5 °C for temperature, ±3% for relative humidity, and ±50 ppm for CO₂ sen-sors. Following ASHRAE guidelines, sensors were installed at a height of 1.1 m from the floor. Prior to the field measurements, all instruments underwent an additional calibration procedure to ensure data precision and experimental reliability.”

 

Comment 5: Please perform more investigation about this research topic, including more students of different ages, different locations, especially different provinces, and different seasons, including wide temperature and humidity ranges. After finishing more investigations, rewrite this paper.

Response: Thank you for your thoughtful suggestion. We acknowledge that this study is limited in geographic and temporal coverage. Due to institutional policy constraints and site access limitations, it was not feasible to conduct measurements across multiple schools. Therefore, the classroom from a school deemed representative of typical primary school buildings in the hot summer and cold winter climate zone were selected as the focus of this exploratory study. The classroom was chosen based on their standard construction, typical occupancy patterns, and administrative approval. While the sample size is limited, the findings provide meaningful preliminary insights into indoor thermal conditions under real-world educational settings. Future research will aim to expand the sample scope across different cities and school types to enhance generalizability. As a pilot case-based study, it aimed to establish a foundational methodology for interpreting classroom thermal comfort in hot summer/cold winter zones. We agree that expanding the study to include multiple provinces, seasons, and student groups of different ages would significantly improve robustness and generalizability. This is already part of our planned follow-up work. We hope the present version demonstrates methodological soundness and provides a useful basis for further large-scale investigations.

 

Comment 6: Please answer this question: if the solar radiation were not considered in this empirical TSV equation, why use the black ball temperature?

Response: Our model prioritizes simplicity and field usability. Because students had uniform dress and seated activities, variables like clothing insulation and metabolic rate were relatively controlled. Temperature and humidity were selected for their direct, measurable impact on thermal sensation. Although solar radiation was not included in the regression model, black globe temperature was recorded to capture the combined influence of air temperature, radiant heat, and convection in the classroom environment. It was used for environmental assessment and cross-checking, but not as a direct input variable for the empirical TSV equation.

 

Comment 7: No line numbers in this paper and the style of reference was not correct.

Response: Thank you for your kind suggestion. We have made the necessary adjustments by adding line numbers throughout the manuscript and revising the reference formatting to fully comply with the MDPI journal style requirements.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

Please, see my attached report.

Comments for author File: Comments.pdf

Author Response

Dear Editors and Reviewer,

We would like to express our sincere gratitude for your valuable time, efforts, and constructive comments, which have significantly improved the clarity and overall quality of our manuscript originally titled “Enhancement of Indoor Thermal Conditions and Standardized Air-Conditioning Management in Representative Primary Educational Institutions in Southern China.”

In the revised version, we have updated the title to “Improving Indoor Thermal Comfort and Air-Conditioning Management in Representative Primary Schools in Southern China” to better reflect the study’s focus and improve readability.

Below, we provide a point-by-point response to each of the reviewers’ comments.  All revisions made to the manuscript have been clearly marked using track changes and addressed accordingly.

 

Comment 1: Title: It is too long. Please, revise it.

Response: Thank you for your suggestion. The title has been revised to " Improving Indoor Thermal Comfort and Air-Conditioning Management in Representative Primary Schools in Southern China " to improve clarity and conciseness.

 

Comment 2: Abstract and conclusion:

- The abstract and conclusion should be detailed by adding more quantitative results given from attractive works.

- Give more details in the conclusion section. I find it lacking in information.

Response: We agree with your suggestion and have revised the conclusion accordingly. Key quantitative findings have been incorporated, and additional clarifications have been added to Conclusions 2 and 3 to better emphasize the significance and relevance of the results.

 

Comment 3: Introduction. It is well-written. However, I suggest author to re-examined it in terms of misspellings.

Response: The introduction has been carefully proofread, and minor spelling and grammar issues have been corrected.

 

Comment 4: Please, you must re-structure the paper and especially integrate references to new publications (2024, 2025, ...). I suggest adding this paper treating similar problem: 10.1002/htj.23031

Response: Thank you for the suggestion. The paper structure has been revised to follow IMRaD. We also added the 2024 reference (DOI: 10.1002/htj.23031) in the literature review section and discussed its relevance.

 

Comment 5: How was the sample size for field measurements determined, and is it representative of seasonal and geographical variability in classroom conditions?

Response: Thank you for your thoughtful suggestion. This study was designed as an exploratory investigation within the hot summer and cold winter climate zone. The selected classroom is part of a primary school constructed in accordance with standardized architectural and educational policies implemented in southern China, making it representative of typical school buildings in the region. The sample site reflects common design practices and operational schedules found across similar climatic zones. While the sample size is limited to one classroom due to logistical and administrative constraints, its selection was based on criteria of regional representativeness. Seasonal variation is acknowledged as a limitation of the present study and will be addressed in future research to capture year-round thermal performance dynamics.

 

Comment 6: Were external factors such as classroom occupancy, students' activity levels, or ventilation considered in the regression model?

Response: Thank you for your thoughtful suggestion. Because students had similar seated activity and uniform clothing, variables such as metabolic rate and clothing insulation were relatively controlled. These were not included as variables but acknowledged as limitations. Ventilation was naturally provided and noted.

 

Comment 7: Why was a linear regression model chosen for predicting TSV instead of more advanced techniques such as machine learning or neural networks?

Response: Linear regression was selected for its simplicity, transparency, and interpretability. The study aims to provide practical tools for educators rather than develop highly complex predictive systems.

 

 

Comment 8: Has the TSVp model been compared with other predictive models in terms of accuracy and robustness?

Response: No direct comparison with other predictive models was conducted in this exploratory study, as the primary objective was to develop a simplified and practical regression model for predicting thermal sensation vote (TSVp) based on ambient classroom conditions. However, future research will consider comparative modeling approaches, such as decision trees, ensemble learning techniques, or machine learning-based regression frameworks, to evaluate and improve predictive performance. While existing literature includes several multiple regression models that link TSV to air temperature alone, models incorporating both temperature and humidity as predictors remain scarce. To our knowledge, few studies have established a dual-variable regression model for TSV in naturally ventilated classroom settings. This underscores the novelty and distinct contribution of the present model, particularly in highlighting the added value of including relative humidity in TSV prediction.

 

Comment 9: How do the results compare with previous studies on the relationship between PMV and TSV? Are there notable discrepancies?

Response: Thank you for your insightful comment. Several previous studies have examined the relationship between PMV and TSV, and many have identified a strong correlation between the two indices under controlled or steady-state conditions. However, discrepancies have also been widely reported, particularly in naturally ventilated or educational environments. These differences are often attributed to factors such as individual adaptation, behavioral adjustments, and local climate characteristics that are not fully captured by the PMV model. Our findings are consistent with this body of literature: while PMV and TSV show general alignment in trend, notable deviations exist, reinforcing the view that PMV may not always accurately reflect the thermal sensation of specific populations—such as schoolchildren—under dynamic real-world conditions.

 

Comment 10: Is the recommended temperature setpoint of 28°C aligned with existing standards for thermal comfort in educational institutions (e.g., ASHRAE 55, ISO 7730)?

Response: The recommended setpoint of 28°C aligns with the upper threshold in adaptive comfort zones outlined in ASHRAE 55 and ISO 7730 for naturally ventilated spaces.

 

Comment 11: Does the study account for the influence of different air-conditioning technologies (e.g., split systems, centralized HVAC, natural ventilation) on thermal comfort?

Response: Thank you for your question. This study was conducted under the constraints of local government regulations and the natural operating conditions of the selected school building. The classrooms surveyed employed a combination of split-type air-conditioning units and natural ventilation, which reflects the common practice in this region. Therefore, the study did not include a comparative analysis of different air-conditioning technologies such as centralized HVAC systems or fully naturally ventilated environments. We acknowledge this as a limitation and plan to explore the influence of various air-conditioning systems in future studies.

 

Comment 12: Were outdoor climatic conditions and dynamic room occupancy integrated into the air-conditioning management strategy?

Response: This study did not quantitatively integrate outdoor climate conditions or dynamic occupancy into the control strategy, but these are important factors for future intelligent system design.”

 

Comment 13: How could the findings be implemented into a smart building management system for automatic air-conditioning control in schools?

Response: The simplified TSV prediction model proposed in this study could be integrated into a smart building management system (BMS) to dynamically adjust indoor temperature setpoints in classrooms. By continuously monitoring temperature and humidity, the system can estimate students’ thermal comfort and optimize AC operation accordingly.

 

Comment 14: Would the conclusions of this study be applicable in other climate zones, especially colder or more humid regions?

Response: This study was conducted in the hot summer/cold winter region of southern China. While the approach may be transferable, validation in colder or more humid regions is necessary before generalizing the model. We acknowledge this as a limitation.

Author Response File: Author Response.docx

Reviewer 4 Report

Comments and Suggestions for Authors

The main comments are as follows:
[1] In "1 Introduction," it is recommended to supplement and analyze the current status of relevant research while highlighting the limitations of existing studies. The innovative of the paper should also be further clarified.
[2] In Table 4 and Table 5, thermal comfort surveys usually follow methods from ASHRAE Standard 55, such as a 7-level thermal sensation scale. However, this study uses only 4 levels. What is the rationale for this simplification? Could it affect statistical results? 
[3] In Section 2.3, please clarify whether a single measurement point was used in each classroom or multiple test points were deployed for indoor thermal environment testing.
[4] In Section 3.1, according to Table 8, air conditioning was operational during some periods. However, the study focuses on thermal comfort under natural conditions. How might air-conditioned survey data impact the results?
[5] Figure 5 presents thermal comfort assessment findings. Further elaboration on the reasons behind this distribution pattern is suggested.
[6] In Section 3.4, the regression equation includes only indoor temperature and relative humidity as independent variables. Why were other influencing variables excluded? How were variables screened?
[7] In Section 3.5, Opening Temperature is derived from the regression equation (as shown in Tables 12 and 13). How was Temperature Setting determined? Further clarification is needed.
[8] Overall, it is recommended to further enrich the content of the paper, and some content should be elaborated in detail.

Author Response

Dear Editors and Reviewer,

We would like to express our sincere gratitude for your valuable time, efforts, and constructive comments, which have significantly improved the clarity and overall quality of our manuscript originally titled “Enhancement of Indoor Thermal Conditions and Standardized Air-Conditioning Management in Representative Primary Educational Institutions in Southern China.”

In the revised version, we have updated the title to “Improving Indoor Thermal Comfort and Air-Conditioning Management in Representative Primary Schools in Southern China” to better reflect the study’s focus and improve readability.

Below, we provide a point-by-point response to each of the reviewers’ comments.  All revisions made to the manuscript have been clearly marked using track changes and addressed accordingly.

 

Comment 1: In "1 Introduction," it is recommended to supplement and analyze the current status of relevant research while highlighting the limitations of existing studies. The innovative of the paper should also be further clarified.

Response: Thank you for your thoughtful suggestion. We have incorporated recent literature on thermal comfort across different climatic regions. In addition, we clarified that humidity is a key yet often overlooked factor influencing TSV. Based on this, we refined the study’s objectives to emphasize the combined impact of temperature and humidity in real-world classroom settings. These revisions have been made in the final paragraph of the Introduction section to better frame the context and rationale of our study.

 

Comment 2: In Table 4 and Table 5, thermal comfort surveys usually follow methods from ASHRAE Standard 55, such as a 7-level thermal sensation scale. However, this study uses only 4 levels. What is the rationale for this simplification? Could it affect statistical results?

Response: Thank you for your thoughtful suggestion. A simplified 4-point thermal sensation scale was adopted in this study to accommodate the cognitive abilities and comprehension levels of primary school students. The choice was made to improve response clarity and reliability, as younger children may struggle to consistently distinguish between the nuanced categories of the 7-point ASHRAE scale. Moreover, since this study was conducted during the summer season only, the inclusion of cold-related categories such as “cool,” “cold,” or “very cold” could introduce conceptual confusion and inflate measurement error among young respondents. This adjustment is supported by prior studies indicating that simplified thermal sensation scales are appropriate and effective when used with children or low-literacy populations (e.g., Oishi et al., 2022). While this scale limits direct comparability with studies using the ASHRAE standard, the trade-off was considered justified in favor of data accuracy and respondent comprehension.

 

Comment 3: In Section 2.3, please clarify whether a single measurement point was used in each classroom or multiple test points were deployed for indoor thermal environment testing.

Response: Thank you for your thoughtful comment. Due to institutional policy constraints and safety considerations, only a single measurement point was used within the classroom. The data collection required long-term continuous monitoring, and the presence of multiple instruments would have interfered with regular classroom activities. Given the young age of the students, who are often freely active during breaks and lack the self-regulation typically observed in adult populations, the risk of accidental interference or equipment damage was a significant concern. Therefore, the measuring device was installed at a carefully selected location considered both representative of the overall classroom environment and least likely to be disturbed by students. This setup was deemed the most practical and reliable under the existing school conditions.

 

Comment 4: In Section 3.1, according to Table 8, air conditioning was operational during some periods. However, the study focuses on thermal comfort under natural conditions. How might air-conditioned survey data impact the results?

Response: Thank you for your thoughtful comment. We would like to clarify that the term “natural conditions” in this study does not refer to the absence of air-conditioning, but rather to the lack of researcher intervention in the indoor environment. All thermal conditions recorded during the study period reflect the natural, everyday behavior of teachers and students, including their autonomous decisions regarding whether and when to operate the air-conditioning. The use of air-conditioning was entirely determined by the classroom occupants, without any imposed control or restriction by the research team. We apologize for any confusion this may have caused and appreciate the opportunity to clarify this point.

 

Comment 5: Figure 5 presents thermal comfort assessment findings. Further elaboration on the reasons behind this distribution pattern is suggested.

Response: Thank you for your suggestion. We have provided additional explanation regarding the distribution pattern presented in Figure 5. This clarification has been added on Page 11 of the revised manuscript to help readers better understand the observed thermal comfort trends.

 

Comment 6: In Section 3.4, the regression equation includes only indoor temperature and relative humidity as independent variables. Why were other influencing variables excluded? How were variables screened?

Response: Thank you for your suggestion regarding the variables included in the regression model. The model was developed based solely on ambient environmental parameters—air temperature and relative humidity—due to both contextual and practical considerations. First, the classroom environment involved relatively uniform conditions: students were seated during class sessions and wore standardized school uniforms, reducing variability in metabolic rate and clothing insulation. These personal variables were therefore excluded from the model. Second, we would like to clarify that the study was not conducted under fully naturally ventilated conditions. Rather, it was carried out under non-intervention conditions, meaning that the use of air conditioning or natural ventilation was entirely at the discretion of the teacher, without any interference or manipulation by the research team. This reflects the real-world thermal environment experienced by students and aligns with the aim of developing a practical, field-based TSV prediction model. While ventilation and air movement were qualitatively observed, they could not be reliably and continuously quantified during the measurement period and were therefore not included in the regression. Furthermore, this exploratory study did not directly compare the proposed model with other advanced prediction models. Instead, it aimed to create a simplified, easy-to-implement regression model using key ambient factors. Although several previous studies have built regression models based on air temperature alone, few have considered both temperature and humidity—particularly in naturally operated (i.e., user-controlled) classroom environments. This highlights the novelty and distinct contribution of our model in emphasizing the role of humidity in predicting students’ thermal sensation. Future research will consider including additional variables such as air velocity and exploring more advanced techniques such as decision trees or ensemble learning methods to further enhance prediction accuracy.

 

Comment 7: In Section 3.5, Opening Temperature is derived from the regression equation (as shown in Tables 12 and 13). How was Temperature Setting determined? Further clarification is needed.

Response: Thank you for your question. The recommended temperature setpoint of 28 °C was derived by solving the regression equation for TSV = 1, which corresponds to the threshold of neutral thermal sensation as reported by students. This value represents the point at which most students perceive the indoor environment as thermally acceptable without discomfort. The resulting guideline, grounded in the empirical regression model, offers a practical framework for optimizing air-conditioning use during the summer, balancing thermal comfort and energy efficiency under real classroom conditions. A detailed explanation has been provided on page 17 of the revised manuscript.

 

Comment 8: Overall, it is recommended to further enrich the content of the paper, and some content should be elaborated in detail.

Response: We appreciate the suggestion. In the revised manuscript, we have expanded descriptions in the Discussion section, clarified regression modeling decisions in the Methods, and improved numerical interpretation in the Results to enhance academic completeness and clarity.

Author Response File: Author Response.docx

Reviewer 5 Report

Comments and Suggestions for Authors

Find Attached please.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The manuscript would benefit from light language editing to improve clarity and reduce redundancy in certain sections. Grammar, sentence structure, and scientific phrasing could be polished for smoother reading.

Author Response

Dear Editors and Reviewer,

We would like to express our sincere gratitude for your valuable time, efforts, and constructive comments, which have significantly improved the clarity and overall quality of our manuscript originally titled “Enhancement of Indoor Thermal Conditions and Standardized Air-Conditioning Management in Representative Primary Educational Institutions in Southern China.”

In the revised version, we have updated the title to “Improving Indoor Thermal Comfort and Air-Conditioning Management in Representative Primary Schools in Southern China” to better reflect the study’s focus and improve readability.

Below, we provide a point-by-point response to each of the reviewers’ comments.  All revisions made to the manuscript have been clearly marked using track changes and addressed accordingly.

 

Comment 1: The manuscript addresses a pressing issue maintaining thermal comfort in educational environments while conserving energy. The use of TSV as an alternative to PMV is a novel approach in this context, and the regression model provides practical implications. However, the originality could be emphasized further by contrasting the findings with international benchmarks or adaptive comfort models.

Response: Thank you for this suggestion. We have added a brief comparative discussion referencing adaptive comfort benchmarks in ASHRAE 55 and other relevant studies, noting how our findings on TSV and the recommended comfort setpoint align with or differ from international data.
The corresponding explanations have been added on pages 2 and 16 of the revised manuscript.

 

Comment 2: Field data collection methods are clear, but the analysis section needs greater detail:

1. Include assumptions and diagnostics for regression analysis (e.g., R² adjusted, multicollinearity checks).
2. Expand on the rationale for selecting 28°C as the comfort setpoint and how it compares with existing standards.
3. Justify the sampling strategy and confirm whether selection bias was addressed in questionnaire distribution.

Response: Thank you for this suggestion.

3. a) We have added the following to Section 3.4 in Page.15: Adjusted R² = 0.281, and VIF < 2 for all predictors, indicating no multicollinearity.
4. b) The recommended temperature setpoint of 28 °C was derived by solving the regression equation for TSV = 1, which corresponds to the threshold of neutral thermal sensation as reported by students. This value represents the point at which most students perceive the indoor environment as thermally acceptable without discomfort. The resulting guideline, grounded in the empirical regression model, offers a practical framework for optimizing air-conditioning use during the summer, balancing thermal comfort and energy efficiency under real classroom conditions. A detailed explanation has been provided on page 17 of the revised manuscript.
5. c) Regarding the sampling strategy, all students in the selected classrooms were invited to participate in the questionnaire, resulting in a high response rate (>95%). As the questionnaire was distributed uniformly during regular

 

Comment 3: The correlation between TSV and PMV is well-explored and statistically significant.

However:

1. Avoid overgeneralizing the TSV model’s reliability without validation across multiple school types or regions.
2. Clarify whether student-reported TSV results were validated for consistency or cognitive bias (e.g., age-appropriate interpretations).

Response: Thank you for this suggestion. Although the TSV-based regression model showed significant trends, we acknowledge that subjective votes from students may involve cognitive variability. To mitigate this, simplified 4-point scales were used and survey guidance was provided. Results should be interpreted within the context of early-age perceptual consistency. While this study was based on classrooms within a specific climate zone, the modeling framework—rooted in environmental parameters—has the potential to be extended to other regions and school types, pending validation.

 

Comment 4: The implications for air-conditioning control and comfort management are meaningful.

Recommendations could be stronger by:

1. Discussing how results can generalize to naturally ventilated or mixed-mode schools.
2. Exploring how smart control systems can integrate this TSV model.

Response: Thank you for your valuable suggestion. We have further elaborated on the implications of our findings in the context of naturally ventilated and mixed-mode schools, as well as the potential integration of the proposed TSV model into smart control systems. These additional discussions have been included on page 16 of the revised manuscript.

 

Comment 5: The manuscript is generally well-organized but would benefit from:

1. Language editing to correct grammatical issues and streamline complex sentences.
2. Improved figure captions and clearer referencing of tables/figures in the main text.
3. A summary limitations section to strengthen transparency.

Response: Thank you for your valuable suggestion. We have performed language editing throughout the manuscript. All figures and tables now include improved captions and are properly cited in the text. A limitations paragraph has been added to the end of the Discussion section.

 

Comment 6: Ethical review and consent procedures, particularly involving minors, should be clarified:

1. Was approval obtained from a school board or ethics committee?
2. Were students and guardians informed about the purpose and anonymity of the questionnaire?

Response: Thank you for your valuable suggestion. We confirm that school administrative approval was obtained and written informed consent was collected from all participants and their guardians prior to survey distribution. And is add in Ethics of approval and consent to participate.

Author Response File: Author Response.docx

Reviewer 6 Report

Comments and Suggestions for Authors

Literature review pertaining to the topic is missing. Add research papers related to thermal comfort survey done in varied climatic regions and decode their key findings. identify the research gap and formulate the objectives of the study.

Hot summers and cold winters - specify the months

Materials and Methods section to be discussed with clarity- data collection- questionnaire survey -Statistical tools used for analysis

Questionnaire survey - Participants of the survey, when was the survey taken, age group, no. of male/ female

How many classrooms were take for study. the author has shown the plan of only one classroom.

The structure of the Paper has to follow scientific method - Introduction, Literature review, materials and methods, Results and discussions, conclusions

Section 3 - research result and analysis - correct as results and analysis

The authors can discuss - what are the adaptive behaviors of occupants if it is too hot or too cold.

Field study - at what height the instruments were placed for data logging. - experimental set up can be discussed.

qualitative study of classrooms - orientation of the classrooms, opening size, 

regression analysis - charts are missing

 

 

 

Author Response

Dear Editors and Reviewer,

We would like to express our sincere gratitude for your valuable time, efforts, and constructive comments, which have significantly improved the clarity and overall quality of our manuscript originally titled “Enhancement of Indoor Thermal Conditions and Standardized Air-Conditioning Management in Representative Primary Educational Institutions in Southern China.”

In the revised version, we have updated the title to “Improving Indoor Thermal Comfort and Air-Conditioning Management in Representative Primary Schools in Southern China” to better reflect the study’s focus and improve readability.

Below, we provide a point-by-point response to each of the reviewers’ comments.  All revisions made to the manuscript have been clearly marked using track changes and addressed accordingly.

 

Comment 1: Literature review pertaining to the topic is missing. Add research papers related to thermal comfort survey done in varied climatic regions and decode their key findings. identify the research gap and formulate the objectives of the study.

Response: Thank you for the valuable comment. We have revised the introduction and added recent literature including studies in urban villages (Zhang et al., 2023) and residential buildings (Li et al., 2023) across diverse climate zones in China. We emphasized that humidity is often underrepresented despite its importance, and we clarified that this study focuses on TSV prediction using ambient temperature and humidity to address that gap in the context of primary schools.

 

Comment 2: Hot summers and cold winters - specify the months

Response: Thank you for the valuable comment. We have added the following to the Methods section: "Based on meteorological records, hot summer months in the region span from June to September, and cold winter months are from December to February." In Page 3.

 

Comment 3: Materials and Methods section to be discussed with clarity- data collection- questionnaire survey -Statistical tools used for analysis

Response: Thank you for the valuable comment. We have revised the Materials and Methods section to provide a clearer explanation of the data collection process, including the questionnaire survey and the statistical tools used for analysis. These details have been added on Page 5 and 6 of the revised manuscript.

 

Comment 4: Questionnaire survey - Participants of the survey, when was the survey taken, age group, no. of male/ female

Response: Thank you for the valuable comment. We have revised the survey to provide a clearer explanation of the data collection process. These details have been added on Page 5 and 6 of the revised manuscript.

 

Comment 5: How many classrooms were take for study. The author has shown the plan of only one classroom.

Response: Thank you for the valuable comment. Due to institutional policy constraints and site access limitations, it was not feasible to conduct measurements across multiple schools.  Therefore, the classroom from a school deemed representative of typical primary school buildings in the hot summer and cold winter climate zone were selected as the focus of this exploratory study.  The classroom was chosen based on their standard construction, typical occupancy patterns, and administrative approval.  While the sample size is limited, the findings provide meaningful preliminary insights into indoor thermal conditions under real-world educational settings.  Future research will aim to expand the sample scope across different cities and school types to enhance generalizability.

 

Comment 6: The structure of the Paper has to follow scientific method - Introduction, Literature review, materials and methods, Results and discussions, conclusions

Response: Thank you for the valuable comment. The revised manuscript has been reorganized to follow the standard scientific structure, including the sections: Introduction, Literature Review, Materials and Methods, Results and Discussion, and Conclusions. The current structure complies with the formatting and organizational guidelines required by MDPI journals.

 

Comment 7: Section 3 - research result and analysis - correct as results and analysis

Response: Thank you for the valuable comment. The section title has been corrected accordingly.

 

Comment 8: The authors can discuss - what are the adaptive behaviors of occupants if it is too hot or too cold.

Response: Thank you for the valuable comment. We have added a brief explanation regarding the adaptive behaviors of occupants, which has been included on Page 5 of the revised manuscript.

Comment 9: Field study - at what height the instruments were placed for data logging. - experimental set up can be discussed.

Response: Thank you for your comment. We have revised the relevant section to include a description of the experimental setup, including the height at which instruments were placed for data logging. This information has been added on Page 6 of the revised manuscript.

 

Comment 10: qualitative study of classrooms - orientation of the classrooms, opening size, 

Response: Thank you for your comment. A qualitative description of the classrooms, including their orientation and opening size, has been added on page 4 of the revised manuscript.

 

Comment 11: regression analysis - charts are missing

Response: Thank you for your comment. We have added the corresponding regression analysis charts to support the findings. These figures have been included on page 15 of the revised manuscript.

 

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

All problems have been replied to adequately.

 

Reviewer 3 Report

Comments and Suggestions for Authors

The paper is acceptable for publication.

Reviewer 4 Report

Comments and Suggestions for Authors

The paper has been revised according to the comments.

Reviewer 5 Report

Comments and Suggestions for Authors

Good Luck!

Reviewer 6 Report

Comments and Suggestions for Authors

Author has carried out the corrections as per the comments given.