A Contrast Experiment on the Ventilation Direction towards Human Head in Personalized Environmental Control System (PECS)

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper investigated the impact of airflow direction towards the head on physiological and psychological sensations. The idea has several practical applications, there are several issues need to be addressed:

1.     Please verify the references cited in the main text, such as in line 43, line 64, etc.

2.     Please review the punctuation and capitalization of words, such as in line 314, line 353, etc.

3.     Is "Relative humidity" accurate in Table 2?

4.     Could you provide the references and data sources for the increased airflow velocity to 1.8m/s?

5.     Is "SB-PV" randomly directed or specified as left or right? Please clarify.

6.     How is the correlation between indoor temperature, airflow velocity, and direction considered?

Author Response

Response On website Reviewer #1

 

Reviewer #1.

This paper investigated the impact of airflow direction towards the head on physiological and psychological sensations. The idea has several practical applications, there are several issues need to be addressed:

Response

Thank for your positive evaluation and all your comments, which are extremely valuable in helping to improve the paper quality. According to your comments, we tried our best to make the appropriate revision and all changes were highlighted in the red color for the easy reference in the revised manuscript.

 

 

Comment 1.

Please verify the references cited in the main text, such as in line 43, line 64, etc.

Response 1:

Thank you for your suggestion and reminder. Due to software version issues, we provided an incorrect citation format that caused confusion for the reviewers. We have improved this issue and checked all references and formatting to ensure the accuracy of the manuscript.

 

Comment 2.

Please review the punctuation and capitalization of words, such as in line 314, line 353, etc.

Response 2:

Thank you for your valuable feedback. We attach great importance to your suggestion to improve scientific rigor. To this end, we have made improvements to the spelling of text and punctuation in the article.

 

Comment 3.  

Is "Relative humidity" accurate in Table 2?

Response 3:

Thank you for your feedback, which is very important to us. We have revised the description in Table 2 to address the issues. The specific location of the modification refers to lines 199.

 

Comment 4.

Could you provide the references and data sources for the increased airflow velocity to 1.8m/s?

Response 4:

Thank you for your comment. You have raised very valuable points.

People living in consistently high-temperature environments may experience varying degrees of physiological effects. If excess metabolic heat in the body is not promptly dissipated, it accumulates, leading to a sensation of warmth, elevation in body temperature, and compromised thermal comfort[*]. The application of airflow can mitigate indoor temperature increases to some extent, offering an opportunity for achieving thermal comfort in indoor environment design.

In ASHRAE 55-2004, the allowance of increased airspeed to offset rising operative temperatures was introduced. However, this practice gained broader acceptance only after the release of ASHRAE 55-2010. What we intend to convey is that existing literature [31][43][44][**] has summarized that within an air temperature range of 26 to 32°C, participants experienced improved thermal comfort when exposed to airflow, with speeds ranging from 0.4 to 3.1 m/s. Reasonably increasing airflow velocity in warm temperatures is an effective means of enhancing thermal comfort. These studies provide guidance for selecting an appropriate airflow velocity for conducting experiments on head-directed airflow. Previous studies have indicated that in a working environment at 29°C, the optimal airflow speed for the entire body is approximately 2.49 m/s, with a 90% comfort range of 1.45-3.53 m/s [43]. Considering that this study focuses on airflow directed towards the head, the suitable airflow speed might be lower. Based on the aforementioned theory, we conducted extensive preliminary experiments to select an airflow speed that does not deviate from this range while providing participants with a moderately strong airflow sensation to better evaluate the impact of airflow direction on the head and overall body perception. After numerous preliminary experiments, we found that an airflow speed of 1.8 m/s meets our research objectives. Therefore, in this experiment, airflow velocity near the human head was maintained at a moderate to high speed of approximately 1.8 m/s by controlling the control valve, facilitating a more thorough evaluation of the influence of airflow directionality on head perception.

 

31. Zhou, ; Zhang, X.; Xie, J.; Liu, J. Effects of elevated air speed on thermal comfort in hot-humid climate and the extended summer comfort zone. Energy Build. 2023, 287, 112953.
32. Chow, T.; Fong, K.F.; Givoni, B.; Lin, Z.; Chan, A.L.S. Thermal sensation of Hong Kong people with increased air speed, temperature and humidity in air-conditioned environment. Build. Environ. 2010, 45, 2177-2183.
33. Zhai, ; Zhang, Y.; Zhang, H.; Pasut, W.; Arens, E.; Meng, Q. Human comfort and perceived air quality in warm and humid environments with ceiling fans. Build. Environ. 2015, 90, 178-185.

[*]：

560. Lundgren Kownacki, C.S. Gao, K. Kuklane, A. Wierzbicka, Heat stress in indoor environments of scandinavian urban areas: a literature review, Int. J. Environ. Res. Publ. Health 2019, 16 , 560.

 X.M. Wang, Y.T. Zhang, Y.M. Huang, J. Yang, Development and validation of an individualized predicted heat strain model for simulating physiological responses in various conditions, Build. Environ. 2022, 214 , 108922.

[**]：

385. Candido, R.J.D. Dear, R. Lamberts, Combined thermal acceptability and air movement assessments in a hot humid climate, Build. Environ. 2011, 46, 379–385.
386. Zhai, H. Zhang, Y. Zhang, et al., Comfort under personally controlled air movement in warm and humid environments, Build. Environ. 2013, 65, 109–117.
387. Schiavon, B. Yang, Y. Donner, et al., Thermal comfort, perceived air quality and cognitive performance when personally controlled air movement is used by tropically acclimatized persons, Indoor Air 2017, 27, 690–702.
388. Lipczynska, S. Schiavon, L.T. Graham, Thermal comfort and self-reported productivity in an office with ceiling fans in the tropics, Build. Environ. 2018, 135, 202–212.
389. Simone, B.W. Olesen, Preferred air velocity and local cooling effect of desk fans in warm environments, In Proceedings of the 34th AIVC conference, 2013.

 

Comment 5.  

Is "SB-PV" randomly directed or specified as left or right? Please clarify.

Response 5:

Thank you for your question. Your question is highly professional and crucial for refining the presentation of our article. Before starting the formal experiment, we conducted preliminary tests where airflow was supplied to the face from both the left and right sides. We found no significant differences in participants' subjective perceptions and physiological indicators between the two sides. Additionally, the human head is bilaterally symmetrical, which supports our experimental results. For convenience in equipment setup during the actual experiment, we consistently directed airflow to the left side of the participants' heads and faces. In the paper, we used the term "Side" instead of "Left/Right" to avoid any confusion for readers regarding potential differences between the sides. Therefore, we appreciate your question and, for a more rigorous presentation of the experimental details, we will make the following improvements.

Addition<<

Among them, "Side blowing" refers to directing airflow to the participants' heads from the left side only. (Our preliminary investigation revealed no significant differences in participants' subjective physiological and psychological feelings between left-side and right-side airflow. Therefore, for the convenience of equipment setup, we consistently directed airflow to the left side of the participants' heads.)

>>

The specific location of the modification refers to lines 111-115.

 

Comment 6. 

How is the correlation between indoor temperature, airflow velocity, and direction considered?

Response 6:

Thank you for your feedback. Your comments are very important.

The correlation between indoor temperature, airflow velocity, and airflow direction is a significant aspect in the study of indoor environmental quality and human comfort. Here are the key considerations:

1. Indoor Temperature: This is a primary factor affecting thermal comfort. Ideal indoor temperatures vary based on activities, clothing, and individual preferences, but generally range between 20-24°C. The results of climate chamber experiment identified suitable range of indoor temperature to use electric fans and their corresponding range of air speeds. The air flow generated by electric fans could be used as an effective cooling method to maintain a comfortable environment at 28 °C–32 °C[26].
2. Airflow Velocity: This refers to the speed at which air moves within a space. It impacts how heat is transferred from the body to the air. Higher airflow velocities can enhance the cooling effect, making a room feel cooler than its actual temperature. Conversely, low airflow can make a room feel stuffy and warm[43].
3. Airflow Direction: The direction of airflow affects how air circulates within a space, influencing temperature distribution and removing contaminants. Effective airflow direction helps maintain consistent temperatures and air quality throughout the room[34].

Correlations and Interactions:

1. Temperature and Airflow Velocity:

• Cooling Effect: Higher airflow velocities can create a cooling sensation due to increased convective heat transfer from the body. This can make higher temperatures feel more comfortable.
• Thermal Stratification: Inadequate airflow can lead to thermal stratification, where warmer air accumulates at higher levels and cooler air remains below, creating uneven temperature distribution.

2. Temperature and Airflow Direction:

• Uniform Temperature Distribution: Proper airflow direction can help achieve uniform temperature distribution. For instance, well-placed vents can ensure warm air from heating systems is effectively distributed throughout the room.
• Draft: Improper airflow direction can cause drafts, which may be uncomfortable even if the temperature is within the desired range.

3. Airflow Velocity and Direction:

• Ventilation Efficiency: The combination of airflow velocity and direction determines the effectiveness of ventilation systems. High velocity with poor direction can cause turbulence and ineffective air mixing, while optimal direction with appropriate velocity ensures efficient air circulation and pollutant removal.
• Occupant Comfort: Balanced airflow direction and velocity minimize drafts and ensure comfortable conditions. For example, airflow directed away from occupants at a moderate velocity can enhance comfort without causing discomfort.

By carefully considering the interactions between indoor temperature, airflow velocity, and direction, it is possible to create indoor environments that enhance comfort, health, and productivity.

 

26. Huang, ; Ouyang, Q.; Zhu, Y.; Jiang, L. A study about the demand for air movement in warm environment. Build. Environ. 2013, 61, 27-33.
27. Toftum, ; Zhou, G.; Melikov, A. Effect of airflow direction on human perception of draught, In Proceedings of Climate 2000 Conference, Brussels, Belgium, August 30th to September 2nd 1997.
28. Chow, T.; Fong, K.F.; Givoni, B.; Lin, Z.; Chan, A.L.S. Thermal sensation of Hong Kong people with increased air speed, temperature and humidity in air-conditioned environment. Build. Environ. 2010, 45, 2177-2183.

Author Response File: Author Response.doc

Reviewer 2 Report

Comments and Suggestions for Authors

I positively relate to your work and recommend it to publish with minor corrections I've included into my review.  

 

Review on manuscript “ A contrast experiment on the ventilation direction towards human head in personalized environmental control system (PECS)” by Canyang Li, Wenkai Fu and Xi Meng

 

The manuscript deals with experimental and about statistical description of effect of personalized ventilation aiming onto human head comfort. Reading manuscript I have several questions: a) in Fig. 11 shown various choices of wind blow effect on a human being health and I don’t understand why back blow ventilation BB-PV causes dizziness as well as blocked breath or dry eyes at all?; b) what has been duration of PV procedure and is it make sense generally? c) it seem to me more important to check or run these investigations covering older population starting with age of 50 till 60? d) And finally, what was exactly the goal given investigations; e) what is novelty of considered research and if it’s possible give us several points of it.

 As a whole, I think this research work accumulates much information and probably can be publish with taking into account minor corrections.             

Author Response

Response On website Reviewer #2

 

Reviewer#2 :

I positively relate to your work and recommend it to publish with minor corrections I've included into my review.  Review on manuscript “ A contrast experiment on the ventilation direction towards human head in personalized environmental control system (PECS)” by Canyang Li, Wenkai Fu and Xi Meng. The manuscript deals with experimental and about statistical description of effect of personalized ventilation aiming onto human head comfort. Reading manuscript I have several questions:

Response#2:

Thank you for your positive evaluation and all your comments, which are extremely valuable in helping to improve the paper quality. We tried our best to make the appropriate revision and all changes were highlighted in the purple color for the easy reference in the revised manuscript.

 

Comment 1.

In Fig. 11 shown various choices of wind blow effect on a human being health and I don’t understand why back blow ventilation BB-PV causes dizziness as well as blocked breath or dry eyes at all?

Response 1:

Thank you for your detailed review and feedback on our paper. Regarding your concerns about the impact of BB-PV on human health in Figure 11, we provide the following explanation:

In our experiment, we selected a medium-high airflow speed of 1.8 m/s. This airflow speed causes most participants to feel a noticeable airflow, and while the backward airflow does not directly impact the face, it can still cause drafts. Firstly, BB-PV directly affects the back of the head and neck, areas where blood flow is crucial for maintaining balance and posture. Strong backward airflow may disrupt neck blood circulation, leading to dizziness and discomfort. Continuous BB-PV might cause localized cooling of the neck and back of the head, affecting overall thermal balance and leading to dizziness. Additionally, BB-PV may create a recirculation effect around the head, with air circulating between the face and neck, increasing resistance to inhaled airflow and causing a sensation of breathlessness. Furthermore, the direct airflow from behind the head can indirectly affect the eyes by drying the skin around them, exacerbating dryness.

Nevertheless, our survey results indicate that the incidences of breathlessness, dizziness, and dry eyes caused by BB-PV are all below 10%, a very low percentage,  supporting our experimental results.

We believe that these supplementary explanations provide a better understanding of the health impacts of BB-PV. Thank you again for your valuable feedback. If you have any further suggestions or questions, we are more than happy to discuss them further.

 

Comment 2:

What has been duration of PV procedure and is it make sense generally?

Response 2:

Thank you for your detailed review and feedback on our paper. Regarding your concerns about the duration of the PV sessions and their rationale, we provide the following explanation:

In our experiment, each PV session was set to last for 20 minutes. This duration is based on standard times from multiple related studies and was validated through preliminary experiments to ensure participants had sufficient time to adapt and perceive the effects of different ventilation directions. The experimental design ensured that each participant experienced 20 minutes of ventilation under each condition to maintain data consistency and comparability.

Choosing 20 minutes as the duration for PV is grounded in existing literature and research. For instance, previous studies[***] have established the time required for skin temperature changes to stabilize, analyzing the impact of head-directed airflow on human skin temperature and the steady-state skin temperature before and after stimulation. Results indicated that under summer conditions, skin temperatures across all body parts stabilized 14 minutes after the onset of airflow stimulation. If the experimental duration is too short, participants' physiological data and subjective perceptions may not stabilize, leading to increased variability and less reliable data. Conversely, excessively long durations may not yield optimal cooling effects and comfort. Therefore, a 20-minute ventilation period ensures that participants recover from the initial temperature change responses, reach a stable thermal comfort state, and provide more reliable comfort evaluation data. This is crucial for assessing the effects of different ventilation directions.

In summary, the 20-minute duration for PV was carefully considered and validated to effectively balance participants' adaptation time and data stability, thereby providing more accurate and reproducible results for our study.

[***] : https://doi.org/10.13837/j.issn.1006-8309.2014.03.0013

 

Comment 3:  

It seem to me more important to check or run these investigations covering older population starting with age of 50 till 60?

Response 3:

Thank you for your insightful comments and suggestions on our manuscript. We appreciate your emphasis on expanding our study to include older adults, particularly those aged 50-60. Here is our perspective on this important consideration:

As you correctly pointed out, individuals aged 50-60 constitute a significant demographic with differing physiological responses to environmental conditions, including thermal comfort. Understanding the impact within this age group is crucial for developing inclusive and effective environmental control strategies.

Research [****] indicates that middle-aged and elderly individuals generally perceive heat sensations as lower by 0.5 units compared to younger people. Additionally, they exhibit greater peripheral vasoconstriction under similar conditions. However, their thermal perception correlates primarily with air temperature, unlike younger individuals whose thermal sensation is also influenced by skin temperature. Elderly individuals prefer higher temperatures under constant conditions compared to younger counterparts. They typically undergo variations in temperature regulation and may have different comfort preferences compared to younger individuals. Studying photovoltaic systems in this age group allows us to assess their potential benefits in reducing discomfort and promoting health.

Your feedback is invaluable and guides our further efforts. We will consider expanding our research scope in future stages to include participants aged 50-60. Building on this foundation, we will continue our research efforts and extend the participant group to meet the specific needs and characteristics of older adults, ensuring robust and relevant data collection.

Thank you once again for your valuable feedback and guidance.

 [****]

• Schellen L, Lichtenbelt W D V M, Loomans M G L C, et al. Differences between young adults and elderly in thermal comfort, productivity, and thermal physiology in response to a moderate temperature drift and a steady-state condition. Indoor Air, 2010, 20, 273-283.
• Ferraro S, Iavicoli S, Russo S, et al. A field study on thermal comfort in an Italian hospital considering differences in gender and age. Applied Ergonomics, 2015, 50, 177-184.
• Zhai Y, Li Z, Chen X, et al. Thermal perception of non-uniform and dynamic air-conditioned environment in the elderly[J]. Journal of Building Engineering, 2023, 76, 107236.

 

 

Comment 4:

What was exactly the goal given investigations？

Response 4 :

Thank you for your comment. This study's findings shed light on a crucial aspect often overlooked in personalized ventilation systems (PV): the impact of airflow direction on human comfort. By demonstrating that directional airflow towards the human head can significantly influence thermal sensation and comfort levels.

First, In building design and HVAC engineering, understanding how airflow direction affects occupants' comfort can inform the design and optimization of personalized ventilation systems. Architects and engineers can leverage this knowledge to tailor airflow patterns in PV systems, ensuring that airflow direction contributes positively to occupant comfort.

Moreover, in the context of indoor air quality and health, optimizing airflow direction based on its effects on thermal sensation can contribute to creating healthier indoor environments. By directing airflow towards the head in personalized ventilation systems, designers can ensure better air distribution and thermal comfort for occupants. This approach not only improves comfort but also helps maintain indoor air quality by facilitating air movement and circulation.

Overall, we have recognized the significance of airflow direction in influencing human comfort expands the scope of practical applications in building . Integrating the understanding of how airflow direction influences human comfort into PECS can enhance the systems' adaptability and responsiveness to occupants' needs.

In order to make our expression more accurate and coherent with the context , it has been modified as follows:

Addition <<

We recognize the impact of airflow direction towards head on human comfort, which expands the applicability of PECS in buildings. This investigation aimed to determine which airflow direction optimizes thermal comfort by potentially lowering mean skin temperature and enhancing subjective comfort ratings. The broader aim was to contribute to the advancement of PECS, enhancing their ability to meet individual thermal comfort requirements.

>> 

The specific location of the modification refers to lines 400-405.

Comment 5:

What is novelty of considered research and if it’s possible give us several points of it.

Response 5:

Thank you for your comment. The innovation of scientific research is crucial. We have summarized and supplemented the following content.

Addition<<

The objectives and novelty of this study are as follows:

• Investigate the changes in skin temperature and thermal and airflow sensation before and after exposure to airflow directed at the head.
• Analyze the impact of airflow direction towards head on human comfort through comparative experiments.

>> 

The specific location of the modification refers to lines 117-122.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The authors tackle an interesting topic and present useful results. However, certain issues need to be addressed:

1. The literature analysis should be more extensive. The authors are encouraged to enhance it with recent, relevant publications related to heating and ventilation systems of buildings such as, for example:

https://doi.org/10.3390/en16052148

2. The authors should proofread the manuscript. E.g., "error! reference not found"

3. There are no references in the manuscript. This is a major issue that compromises the scientific value of the manuscript. 

4. How would a different age group affect the presented outcome? For example people around their 50s are expected to provide different outcomes.

5. The questionnaire of Figure 4 should be in Appendix.

 

The authors tackle an interesting topic which is experimenting on the ventilation direction towards human head in personalized environmental control system and present useful results. However, certain issues need to be addressed: 1. The authors should point out the scientific contribution of their study more, especially in comparison to other/previous studies. 2. The literature analysis should be more extensive. The authors are encouraged to enhance it with recent, relevant publications related to heating and ventilation systems of buildings such as, for example: https://doi.org/10.3390/en16052148 3. The authors should proofread the manuscript. E.g., "error! reference not found" 4. There are no references in the manuscript. This is a major issue that compromises the scientific value of the manuscript. 5. How would a different age group affect the presented outcome? For example people around their 50s are expected to provide different outcomes. 6. The questionnaire of Figure 4 should be in Appendix. 7. The authors could further enhance the conclusions, commenting on their main quantitative results.

Author Response

Response On website Reviewer #3

 

Reviewer #3:

The authors tackle an interesting topic which is experimenting on the ventilation direction towards human head in personalized environmental control system and present useful results. However, certain issues need to be addressed: 

Response #3:

Thank for your positive evaluation and all your comments, which are extremely valuable in helping to improve the paper quality. According to your comments, we tried our best to make the appropriate revision and all changes were highlighted in the green color for the easy reference in the revised manuscript.

 

 

Comment 1:  

The authors should point out the scientific contribution of their study more, especially in comparison to other/previous studies.

Response 1:

Thank you for your comment. This study's findings shed light on a crucial aspect often overlooked in personalized ventilation systems (PV): the impact of airflow directionality on human comfort. By demonstrating that directional airflow towards the human head can significantly influence thermal sensation and comfort levels.

First, In building design and HVAC engineering, understanding how airflow direction affects occupants' comfort can inform the design and optimization of personalized ventilation systems. Architects and engineers can leverage this knowledge to tailor airflow patterns in PV systems, ensuring that airflow direction contributes positively to occupant comfort.

Moreover, in the context of indoor air quality and health, optimizing airflow directionality based on its effects on thermal sensation can contribute to creating healthier indoor environments. By directing airflow towards the head in personalized ventilation systems, designers can ensure better air distribution and thermal comfort for occupants. This approach not only improves comfort but also helps maintain indoor air quality by facilitating air movement and circulation.

Overall, we have recognized the significance of airflow direction in influencing human comfort expands the scope of practical applications in building . Integrating the understanding of how airflow direction influences human comfort into PECS can enhance the systems' adaptability and responsiveness to occupants' needs.

In order to make our expression more accurate and coherent with the context , it has been modified as follows:

Addition <<

We recognize the impact of airflow direction towards head on human comfort, which expands the applicability of PECS in buildings. This investigation aimed to determine which airflow direction optimizes thermal comfort by potentially lowering mean skin temperature and enhancing subjective comfort ratings. The broader aim was to contribute to the advancement of PECS, enhancing their ability to meet individual thermal comfort requirements.

>> 

The specific location of the modification refers to lines 400-405.

 

Comment 2:

The literature analysis should be more extensive. The authors are encouraged to enhance it with recent, relevant publications related to heating and ventilation systems of buildings such as, for example: https://doi.org/10.3390/en16052148

Response 2:

Thank you for your insightful comments and suggestions on our manuscript. According to your suggestion, we properly cite the article as:

2.Rotas, R., Fotopoulou, M., Drosatos, P., Rakopoulos, D., & Nikolopoulos, N. Adaptive Dynamic Building Envelopes with Solar Power Components: Annual Performance Assessment for Two Pilot Sites. Energies. 2023, 16, 2148.

 

Comment 3:

The authors should proofread the manuscript. E.g., "error! reference not found"

Response 3:

Thank you for your suggestion and reminder. We have checked all citations and formatting to ensure the accuracy of the manuscript.

 

Comment 4:

There are no references in the manuscript. This is a major issue that compromises the scientific value of the manuscript.

Response 4:

Thank you for your suggestion and reminder. Due to software version issues, we provided an incorrect citation format that caused confusion for the reviewers. We have improved this issue and checked all references and formatting to ensure the accuracy of the manuscript.

 

Comment 5:

How would a different age group affect the presented outcome? For example people around their 50s are expected to provide different outcomes.

Response 5:

Thank you for your insightful comments and suggestions on our manuscript. We appreciate your emphasis on expanding our study to include older adults, particularly those aged 50s. Here is our perspective on this important consideration:

As you correctly pointed out, individuals aged 50s constitute a significant demographic with differing physiological responses to environmental conditions, including thermal comfort. Understanding the impact within this age group is crucial for developing inclusive and effective environmental control strategies.

Research [****] indicates that middle-aged and elderly individuals generally perceive heat sensations as lower by 0.5 units compared to younger people. Additionally, they exhibit greater peripheral vasoconstriction under similar conditions. However, their thermal perception correlates primarily with air temperature, unlike younger individuals whose thermal sensation is also influenced by skin temperature. Elderly individuals prefer higher temperatures under constant conditions compared to younger counterparts. They typically undergo variations in temperature regulation and may have different comfort preferences compared to younger individuals. Studying photovoltaic systems in this age group allows us to assess their potential benefits in reducing discomfort and promoting health.

Your feedback is invaluable and guides our further efforts. We will consider expanding our research scope in future stages to include participants aged 50s. Building on this foundation, we will continue our research efforts and extend the participant group to meet the specific needs and characteristics of older adults, ensuring robust and relevant data collection.

Thank you once again for your valuable feedback and guidance.

 [****]

• Schellen L, Lichtenbelt W D V M, Loomans M G L C, et al. Differences between young adults and elderly in thermal comfort, productivity, and thermal physiology in response to a moderate temperature drift and a steady-state condition. Indoor Air, 2010, 20, 273-283.
• Ferraro S, Iavicoli S, Russo S, et al. A field study on thermal comfort in an Italian hospital considering differences in gender and age. Applied Ergonomics, 2015, 50, 177-184.
• Zhai Y, Li Z, Chen X, et al. Thermal perception of non-uniform and dynamic air-conditioned environment in the elderly[J]. Journal of Building Engineering, 2023, 76, 107236.

 

Comment 6:

The questionnaire of Figure 4 should be in Appendix.

Response 6:

Thank you for your suggestions and reminders; they have been very helpful in maintaining the rigor of our paper. We have included the questionnaire image of Figure 4 in the appendix.

 

Comment 7:

The authors could further enhance the conclusions, commenting on their main quantitative results.

Response 7:
Thank you for your comments and suggestions; they are highly constructive for our research.

Our results encompass relevant physiological and psychological indicators, primarily including the reduction in skin temperature, improvement in thermal sensation, enhancement of comfort levels, and overall willingness evaluation, as detailed below:This study evaluated the effects of different airflow directions in personalized ventilation (PV) systems (including front blowing FB-PV, side blowing SB-PV, back blowing BB-PV, and top blowing TB-PV) and a control group (No-PV) on participants' physiological and psychological responses. In the No-PV condition, the system was turned off, while in the other four experimental groups, the airflow around the head was maintained at 1.8 m/s. The experiment was conducted indoors at an air temperature of 29.0 ± 0.5°C and a relative humidity of 60 ± 5%. Fifty-six participants were invited to assess the thermal environment and measure skin temperature. The primary findings are as follows:

• Skin temperature reduction:

Personalized ventilation in the directions of front blowing FB-PV, side blowing SB-PV, back blowing BB-PV, and top blowing TB-PV resulted in a reduction in mean skin temperature (MST) by 0.4-0.6°C, indicating that personalized ventilation effectively lowers skin temperature.

• Improvement in thermal sensation:

Personalized ventilation improves thermal sensation, particularly front blowing FB-PV, with a thermal sensation vote (TSV) of -0.77 (between “slightly cool (-1)” and “neutral (0)”). The TSV of top blowing TB-PV was -0.04 (very close to “neutral (0)”), showing the best thermal sensation. This trend was evident in both skin temperature and thermal sensation.

• Comfort levels:

Top blowing TB-PV showed the highest comfort level, with a score of +1.05 (slightly above “just comfortable (+1)”), while front blowing FB-PV, due to continuous airflow causing breathing discomfort, had a comfort score of -1.11 (slightly below “just uncomfortable (-1)”).

• Overall willingness:

Regarding overall willingness, top blowing TB-PV scored the highest at +1.21 (between “willing (+1)” and “very willing (+2)”). Scores for front blowing FB-PV and side blowing SB-PV were +0.57 and +0.68, respectively (between “neutral (0)” and “willing (+1)”). Back blowing BB-PV had the lowest score at -0.18 (slightly below “neutral (0)”).

Thank you once again for your valuable feedback and guidance.

 

Addition <<

• Skin temperature reduction：FB-PV, SB-PV, BB-PV, and TB-PV towards head led to MST reductions of 0.4-0.6℃, which showed that PV can efficaciously mitigate the skin temperature.
• Improvement in thermal sensation：PV towards the head could improve thermal sensation, especially for FB-PV, which TSV was -0.77 (between ''Slightly cool (-1)'' and '' Neutral (0)''). TB-PV was -0.04 (Very close to ''Neutral (0)''), which had the optimal thermal sensation. The same trend was observed for skin temperature and thermal sensation.
• Enhancement of comfort level：TB-PV demonstrated the highest comfort level with +1.05 (Slightly higher than ''Just comfortable (+1)''), while it was on the contrary for FB-PV of -1.11 (Slightly lower than ''Just uncomfortable (-1)'') due to the discomfort freedom to breathe under the continuous airflow.
• Overall willingness evaluation：TB-PV was the highest score of +1.21 (between ''Willing (+1)'' and ''Very willing (+2)''). FB-PV and SB-PV scored +0.57 and +0.68 (Between ''Neutral (0)'' and ''Willing (+1)''.), respectively. BB-PV was recorded as the lowest level of -0.18 (Slightly lower than ''0 (neutral)'').

>> 

The specific location of the modification refers to lines 384-399.

Author Response File: Author Response.docx

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The authors have addressed all comments. Best of luck with the manuscript's future course!