Assessing the Impact of Urban Area Size on Thermal Comfort in Compact Urban Fabrics Considering the Saharan City of Ghardaïa, Algeria

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. This study explores the correlation between urban scale and compactness, the key factors of desert city type, and the indoor and outdoor thermal behavior of the built environment. The purpose of this study is to focus on the impact of settlement type on the thermal environment in desert areas, which is of great significance.

2. Please explain the background of weather conditions in the study area and the reason for choosing to use UTCI instead of using other heat indices such as Physiological Equivalent Temperature (PET). (Original page 6)

3. Please provide additional information on the data sources for Table 2. Thermophysical Properties of Traditional Building Materials in Ghardaïa. If it is a reference, please add literature citations or data measured in this study. (Original page 15)

4. In the Simulation study, Table 2 is used as the input building material parameters. Are the emissivity and reflectivity of the material taken into account? Because these two key parameters affect the heat absorption of the building, which in turn affects the indoor temperature. (Original page 17)

5. Please confirm the title number. 5. Conclusions is 4 or 5. There is no fourth title item in the article. (Original page 30)

6. The conclusion is too divergent, and it is recommended to focus convergently in order to emphasize the insights and hypotheses of this study.

7. The entire article should concisely discuss the key points of each research and avoid being too lengthy. Please streamline the content of the article appropriately.

Author Response

Please find attached a detailed point-by-point response to each of the reviewers' comments, outlining how their valuable suggestions have been addressed. All revisions have been incorporated into the updated manuscript accordingly.

We trust that the attached document provides clarity and demonstrates our commitment to improving the manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript titled "Assessing the Impact of Urban Area Size on Thermal Comfort and Energy Saving Potential in Compact Urban Fabrics Considering the Saharan City of Ghardaïa, Algeria". However, I did not see any analysis on "building energy".

The manuscript titled "Assessing the Impact of Urban Area Size on Thermal Comfort and Energy Saving Potential in Compact Urban Fabrics Considering the Saharan City of Ghardaïa, Algeria". However, the paper assesses the outdoor thermal comfort outside the city. What is the point of this purpose? People are living in the city.

The authors claim they have compared the urban area size. To me, the author's work is more like defining accurate boundary conditions for building simulation. Cities with different building densities exist and are relevant to urban design. However, does the scenario proposed by the author really exist? In other words, is the conclusion helpful in improving urban design?

 There is no any useful information readers can get from the huge figures of 4 and 5. Readers concerned with scientific issues are not interested in software operation.

The author's work is more like defining accurate boundary conditions for building simulation. Cities with different building densities exist and are relevant to urban design. However, does the scenario proposed by the author really exist? In other words, is the conclusion helpful in improving urban design?

In conclusion, the authors mentioned "...leverage neighbourhood structure to enhance shading and airflow, ..." Are the authors sure that the simple plugin Ladybug includes a CFD calculation module?

To sum up, the authors did a lot of work. But I am so sorry that I failed to find practical meaning of this study.

Author Response

Please find attached a detailed point-by-point response to each of the reviewers' comments, outlining how their valuable suggestions have been addressed. All revisions have been incorporated into the updated manuscript accordingly.

We trust that the attached document provides clarity and demonstrates our commitment to improving the manuscript.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This is a very interesting work, I believe minor extra work is needed. For example, figures 4 and 5 need to be improved, they look crowded and some of their labels are really difficult to read. The font used for equations is too large.

I also have some questions.

In equation 2 are both Ta and Tmrt in Kelvin?

In equation 3, the view factor for each surface was used in reference to what a point, a surface?

How were the neighborhood sizes chosen? What was the criterium?

Was the uncertainty of the measurements carried out with Testo 480 considered in the comparison to simulation results?

Author Response

Please find attached a detailed point-by-point response to each of the reviewers' comments, outlining how their valuable suggestions have been addressed. All revisions have been incorporated into the updated manuscript accordingly.

We trust that the attached document provides clarity and demonstrates our commitment to improving the manuscript.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

1. Each chapter of the article should be concise to avoid the overall length of the article being too lengthy. Please appropriately streamline and reduce the number of pages of the article to avoid boring reading for readers.

2. Page 29 is titled 3.2.2. UTCI Simulation results and is discussed on page 31, continuing to Conclusions, but the current file still displays 5. Conclusions.

3. This research contribution shows that the improvements in outdoor thermal comfort observed at larger urban scales highlight the importance of compact urban design in arid regions.

Author Response

Point 1:  Each chapter of the article should be concise to avoid the overall length of the article being too lengthy. Please appropriately streamline and reduce the number of pages of the article to avoid boring reading for readers.

Response 1:  Thank you for your suggestion and comments. The manuscript has been carefully reviewed and partially restructured to streamline the content, ensuring each section is concise and to the point. Your comments have been addressed in the revised manuscript-round 2.

Point 2:  Page 29 is titled 3.2.2. UTCI Simulation results and is discussed on page 31, continuing to Conclusions, but the current file still displays 5. Conclusions.

Response 2:  Thank you for pointing this out. In the latest version of the revised manuscript, we have addressed this issue by adjusting the title number of the Conclusions’ section. The overall structure of the paper has been corrected to ensure clarity and alignment. Could you please check Page: 28/32, 4. Conclusions.

Point 3:  This research contribution shows that the improvements in outdoor thermal comfort observed at larger urban scales highlight the importance of compact urban design in arid regions.

Response 3:  Thank you for your comment. The authors appreciate your observation and agree that the research’s findings emphasize the significant impact of compact urban design on improving outdoor thermal comfort, particularly in hot, arid regions. In this regard, the Conclusions’ section has been improved to be more focused and aligned with the main insights and hypotheses of the study. Could you please check Page: 28/32, 4. Conclusions.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

I feel angry and confused about the authors' attitude. They might spend five minutes to address two of my comments with AI tool, maybe ChatGPT. The manuscript is still poor and meaningless. Therefore I must recommend rejection.

Author Response

Point 1:  The manuscript titled "Assessing the Impact of Urban Area Size on Thermal Comfort and Energy Saving Potential in Compact Urban Fabrics Considering the Saharan City of Ghardaïa, Algeria". However, I did not see any analysis on "building energy".

Thank you for your suggestion and observation. To better align the title with the content of the manuscript, the title has been revised to:

" Assessing the Impact of Urban Area Size on Thermal Comfort in Compact Urban Fabrics Considering the Saharan City of Ghardaïa, Algeria "

Point 2:  The manuscript titled "Assessing the Impact of Urban Area Size on Thermal Comfort and Energy Saving Potential in Compact Urban Fabrics Considering the Saharan City of Ghardaïa, Algeria". However, the paper assesses the outdoor thermal comfort outside the city. What is the point of this purpose? People are living in the city.

Thank you for this observation.

 In the context of the M'zab Valley, including Ghardaïa, the distinction between "inside" and "outside" the city is not strictly defined in the conventional sense. The term Ksar refers to a traditional compact urban settlement, designed as an integrated system where indoor and outdoor spaces are equally vital to the community's social, cultural, and functional life. Outdoor spaces, including streets, courtyards, and plazas, are essential extensions of indoor environments and play a critical role in daily activities, such as social gatherings, markets, and circulation.

Assessing outdoor thermal comfort is essential for several reasons:

Outdoor Spaces as Living Environments: In the Ksar, outdoor spaces are not merely transitional areas; they are living spaces where significant social and economic interactions occur. Their thermal comfort directly influences the usability and livability of the entire settlement.

Interconnected Thermal Dynamics: The thermal performance of outdoor spaces affects indoor conditions by influencing heat exchange, shading, and airflow. For example, a well-shaded outdoor area can reduce heat gain in adjacent buildings, improving indoor thermal comfort and energy efficiency.

Walkability and Accessibility: The compact urban fabric of the Ksar relies entirely on walkability. Unlike modern urban areas, the design of the Ksar does not accommodate the use of cars or other vehicles due to its narrow streets and dense urban form. As a result, residents depend exclusively on walking as their primary mode of transportation. This makes the thermal comfort of outdoor spaces critical, as the streets and pathways serve as the main routes for mobility. Comfortable outdoor thermal conditions enable residents to navigate their environment safely and without heat stress, particularly during extreme summer conditions.

Narrow Streets in Dry Climates: Narrow streets, a hallmark of traditional Ksour, play a key role in mitigating extreme climatic conditions. These streets maximize shading, limiting solar exposure and reducing heat accumulation. Additionally, their design promotes natural airflow, enhancing cooling effects and improving thermal comfort for pedestrians. These features are essential in hot, arid climates, protecting human health by reducing the risk of heat-related illnesses.

Cultural and Social Preferences: The residents of the Ksar value the compact urban form that encourages walking and fosters strong social connections. The design of outdoor spaces aligns with these cultural preferences, emphasizing pedestrian-friendly environments over vehicular access. Assessing outdoor thermal comfort is critical to maintaining the usability and cultural relevance of these spaces, ensuring they remain central to the community's way of life.

Broader Implications for Urban Design: Studying outdoor thermal comfort provides insights into how urban morphology and design features, such as narrow streets, building orientation, and shading, contribute to mitigating heat stress. These lessons are valuable for improving both current and future urban planning strategies in similar hot-arid climates.

While people live inside buildings, their interaction with outdoor spaces is integral to the quality of life in the Ksar. The absence of vehicles and reliance on walking further underlines the importance of outdoor thermal comfort in ensuring a functional and healthy urban environment. This clarification has been added to the revised manuscript to communicate better the purpose and significance of assessing outdoor thermal comfort in this context.

Point 3:  The manuscript titled "Assessing the Impact of Urban Area Size on Thermal Comfort and Energy Saving Potential in Compact Urban Fabrics Considering the Saharan City of Ghardaïa, Algeria". However, the paper assesses the outdoor thermal comfort outside the city. What is the point of this purpose? People are living in the city.

The study presented in the manuscript addresses an essential and specific aspect of urban design in the Saharan context, particularly within the Ksar of Ghardaïa. While the scenarios analyzed in the study might appear theoretical, they are firmly rooted in the unique characteristics and challenges of traditional Saharan settlements.

The Ksar of Ghardaïa represents a traditional compact urban morphology where urban size and density have evolved as integral responses to harsh desert conditions. The research does not only define boundary conditions for simulations but also evaluates the microclimatic and thermal impacts of varying neighborhood sizes (20m, 40m, and 60m), which are realistic extensions of the existing urban fabric.

This approach has practical implications for urban design:

1. Relevance of Urban Size in Compact Cities: The study demonstrates that larger urban configurations improve outdoor thermal comfort by enhancing shading and ventilation, reducing both heat and cold stress. These findings provide a framework for optimizing neighbourhood size in compact urban forms to achieve better thermal performance without compromising the socio-cultural fabric.
2. Scenarios Reflect Realistic Urban Extensions: The neighbourhood sizes selected for analysis correspond to realistic variations that could emerge in expanding or redeveloping existing Ksour. These scenarios provide actionable insights for designing extensions that maintain the thermal and functional advantages of compact urban forms.
3. Practical Contributions to Urban Design: The findings are directly applicable to the design of new urban areas or the modification of existing ones in arid climates. For example, the research highlights how urban configurations can balance shading and airflow to improve thermal comfort, which is a critical consideration in sustainable urban planning.
4. Implications Beyond the Case Study: Although focused on Ghardaïa, the principles and findings of this study extend to other regions with similar climatic conditions and urban challenges. The insights gained contribute to a broader understanding of the relationship between urban morphology, microclimate regulation, and human comfort.

Point 4:  There is no useful information readers can get from the huge Figures 4 and 5. Readers concerned with scientific issues are not interested in software operation.

Figures 4 and 5 have been updated to emphasize the methodological workflow and outcomes, shifting the focus away from the software's operational specifics. The revised figures highlight  Figure 4; the main steps involved in integrating simulation tools (Ladybug, Honeybee, and EnergyPlus) with field data. Regarding figure 5; The methodology for calculating thermal comfort indices, including UTCI and operative temperature.

Point 5: The author’s work is more like defining accurate boundary conditions for building simulation. Cities with different building densities exist and are relevant to urban design. However, does the scenario proposed by the author really exist? In other words, is the conclusion helpful in improving urban design?

The proposed scenarios depict plausible variations in neighborhood size and layout typical of traditional Saharan settlements, like those found in the Ksar of Ghardaïa. These configurations illustrate potential approaches to urban expansion or redevelopment that align with historical and socio-cultural contexts.

Point 6:  In conclusion, the authors mentioned”….. leverage neighborhood structure to enhance shading and airflow, …” Are the authors sure that the simple plugin ladybug includes a CFD calculation module?

Response:

The authors' statement about leveraging neighborhood structure to enhance shading and airflow suggests an advanced level of simulation, potentially involving Computational Fluid Dynamics (CFD). However, the simple Ladybug plugin does not inherently include a CFD calculation module. Ladybug primarily focuses on climate analysis, solar radiation studies, and daylight analysis, relying on tools like EnergyPlus for energy simulations as done in this workflow.

The CFD-based results, needs an additional plugin or tool, which is Butterfly, which integrates with Ladybug Tools for CFD simulations via OpenFOAM. Regarding this study authors used the dynamic performance simulations to analyze indoor and outdoor thermal behavior and operative temperature (OT) simulations using the Ladybug tool within the Grasshopper environment, complemented by Universal Thermal Climate Index (UTCI) simulations

 

Author Response File: Author Response.pdf

Round 3

Reviewer 2 Report

Comments and Suggestions for Authors

The authors has improved the manuscript. I have no further comment at this moment.