نوع مقاله : مقاله پژوهشی

نویسندگان

1 دانش‌آموخته کارشناسی ارشد، بخش شهرسازی، دانشکده هنر و معماری، دانشگاه شیراز، شیراز، ایران.

2 دانشیار، بخش شهرسازی، دانشکده هنر و معماری، دانشگاه شیراز، شیراز، ایران.

10.22034/urbs.2024.140859.5017

چکیده

با افزایش نرخ شهرنشینی و پیدایش پیامدهای زیست‌محیطی، ضمن افزایش تقاضای انرژی برای تعدیل شرایط حرارتی، اهمیت پیامدهای خرداقلیمی توسعه شهری نزد طراحان و برنامه‌ریزان شهری دوچندان شد. طراحی بهینه هندسه شهری می‌تواند به منظور تعدیل شرایط خرداقلیمی و ارتقای کیفیت فضاهای شهری مفید واقع گردد. هندسه شهری همساز با اقلیم بافت تاریخی شهر شیراز گواهی است بر این مدعا که با به کارگیری سیاست‌های طراحانه توانسته بود شرایط آسایش حرارتی مناسبی را در فضاهای شهری به وجود آورد. با توجه به این که این ساختار ارزشمند تاریخی همچون سایر بافت‌های پویای شهری در معرض تحول و دگرگونی قرار دارد، پژوهش حاضر بر آن است تا به مقایسه تطبیقی عملکرد هندسه شهری تاریخی محدوده مطالعاتی و بررسی پیامدهای خرداقلیمی منتج از تغییرات هندسه شهری صورت گرفته در آن بپردازد. در این راستا، با روشی توصیفی_تحلیلی با بهره‌مندی از مطالعه و تحلیل اسناد، تصاویر و نقشه‌های تاریخی و پیمایش میدانی، هندسه شهری تاریخی و معاصر محدوده مطالعاتی در محیط نرم‌افزار انویمت شبیه‌سازی شده و شرایط خرداقلیمی و سطح آسایش حرارتی منتج از دو گونه بافت شهری مورد ارزیابی تطبیقی قرار گرفته است. اعتبارسنجی داده‌های حاصل از این شبیه‌سازی با برداشت میدانی شاخص خرداقلیمی دما در تاریخ 10تیرماه و محاسبه ضریب همبستگی داده‌های اندازه‌گیری و شبیه سازی شده به اثبات رسید. نتایج حاصل از پژوهش حاضر نشان داده با تغییرات کالبدی صورت گرفته شاخص‌های هندسه شهری مطالعاتی نسبت ارتفاع به عرض و شاخص دید به آسمان به طور میانگین به ترتیب 58.41درصد کاهش و 42.71درصد افزایش یافته‌اند. در نتیجه این تغییرات، دمای هوا در محدوده به طور میانگین 0.3درجه سلسیوس افزایش یافته است. همچنین دمای تابشی افزایش چشمگیری داشته و با کاهش سطوح تحت پوشش سایه همراه بوده است. در ادامه به سبب تخریب موانع کالبدی هدایت‌کننده جریان هوا، سرعت باد افزایش یافته و سطح رطوبت را به حداقل رسانده است. برآیند تغییرات یادشده کاهش سطح آسایش حرارتی را در محدوده مطالعاتی به دنبال داشته است. بدین ترتیب ضروری می‌نماید ضمن جلوگیری از تغییرات گسترده‌تر این بافت ارزشمند، از الگوهای هندسه شهری تاریخی برای بهبود شرایط خرداقلیمی فضاهای شهری و توسعه همساز با اقلیم کلانشهر شیراز بهره گرفته شود.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Evaluation of the Impact of Urban Geometric Transformation on Microclimatic Conditions and Thermal Comfort (Case Study: Sang-e Siah Historical Quarter, Shiraz)

نویسندگان [English]

  • Kimia Haghnegahdar 1
  • mahsa sholeh 2
  • Sahand Lotfi 2
  • Alireza Sadeghi 2

1 Department of Urban Planning and Design, Faculty of Art & Architecture, University of Shiraz, Shiraz, Iran.

2 Department of Urban Planning and Design, Faculty of Art & Architecture, University of Shiraz, Shiraz, Iran.

چکیده [English]

Highlights
- The historical design of the Sang-e Siah neighborhood passively harmonized with climatic conditions, ensuring high spatial quality and thermal comfort.
- Physical modifications in Shiraz's historical urban fabric have weakened the ability of urban geometry to regulate microclimatic conditions effectively.
- Neglecting the microclimatic effects of urban geometry leads to a decline in both thermal comfort and environmental quality in urban open spaces.
- The principles embedded in Shiraz's historical urban design provide valuable insights for sustainable and climate-responsive urban development.
Introduction
The rapid pace of urbanization and its associated environmental challenges, coupled with the rising demand for energy to regulate thermal conditions, have underscored the necessity of addressing the microclimatic consequences of urban development. Given the increasing global temperatures and the urgency of climate adaptation, it is essential to examine the impact of urban form on microclimatic conditions and thermal comfort.
The historical urban fabric of Shiraz, particularly in the Sang-e Siah neighborhood, represents an exemplary case of passive adaptation to climatic conditions. Through careful spatial planning, traditional urban layouts optimized thermal comfort by minimizing solar exposure and enhancing ventilation. However, recent modifications to the city's historical districts have undermined these adaptive strategies, leading to increased urban heat stress and a reduction in outdoor comfort levels.
Meteorological records from Shiraz indicate a persistent rise in average temperatures, aligning with global climate change trends. These data highlight the importance of incorporating climate-sensitive urban design strategies to improve thermal comfort. The traditional design of Shiraz’s historic districts, characterized by narrow alleys, shaded pathways, and strategically oriented streets, exemplifies an effective response to the city's climatic challenges. This study aims to quantitatively assess the impact of geometric transformations in the Sang-e Siah neighborhood on microclimatic conditions and thermal comfort.
Theoretical Framework
Urban geometry consists of key parameters such as the sky view factor (SVF), height-to-width (H/W) ratio, and street orientation, all of which play a critical role in influencing climatic factors such as solar radiation exposure, wind flow, temperature distribution, and humidity retention. These elements collectively determine the thermal comfort of outdoor urban spaces.
A reciprocal relationship exists between urban microclimates and broader climatic systems, with urban geometry serving as a crucial intermediary. By adopting climate-responsive urban design principles, planners and designers can mitigate unfavorable microclimatic effects, ensuring more livable and thermally comfortable urban environments. This study examines the extent to which changes in urban form influence these parameters and provides recommendations for sustainable urban planning practices.
Methodology
This research employs a descriptive-analytical approach and falls within the category of applied studies. Data collection was carried out through a combination of historical document analysis, field surveys, and meteorological data evaluation. The ENVI-met software, a highly reliable microclimate simulation tool, was utilized to model the impact of physical alterations on thermal comfort in the Sang-e Siah neighborhood.
To ensure the accuracy of the findings, simulated results were compared against on-site temperature, humidity, and wind speed measurements. The study focused on the hottest day of the year—July 1, 2022—to capture extreme temperature conditions and their effects on urban microclimates. This methodological approach provides a robust basis for assessing the thermal performance of the historical urban geometry and its contemporary modifications.
Discussion and Findings
The findings of this study underscore the significant impact of geometric transformations in the neighborhood on microclimatic conditions. Specifically, the increase in SVF and the reduction in H/W ratios have resulted in the following effects:

Elevated ambient temperatures due to increased exposure to solar radiation.
Enhanced radiant heat effects, leading to a measurable decline in thermal comfort.
Increased wind speeds in specific areas, contributing to dust dispersion while simultaneously reducing humidity levels.
Decreased humidity, which intensifies heat stress and exacerbates outdoor discomfort.

These combined effects have significantly reduced outdoor thermal comfort in the study area. The results emphasize the importance of maintaining traditional urban design principles to ensure microclimatic stability in historic districts.
Conclusion
This study confirms that urban geometry variables such as SVF, H/W ratio, and street orientation play a fundamental role in shaping microclimatic conditions. The historical structures in Shiraz were designed in harmony with local climatic conditions, employing passive cooling strategies that enhanced thermal comfort in outdoor spaces. However, modern transformations—particularly the widening of streets and reductions in building heights—have disrupted this balance, exacerbating urban heat stress.
To promote sustainable urban development, urban planners and designers should integrate lessons from Shiraz’s historical urban fabric. Strategies such as limiting SVF through shaded pathways, maintaining optimal H/W ratios for improved thermal regulation, and orienting streets to maximize natural ventilation can serve as effective guidelines for improving urban thermal comfort in Shiraz and other arid cities experiencing similar climatic challenges.

کلیدواژه‌ها [English]

  • Thermal comfort
  • climate-responsive design
  • urban geometry
  • urban microclimate
  • Sang-e Siah Historical Quarter
  • Shiraz
Acero, J. A., & Herranz-Pascual, K. (2015). A comparison of thermal comfort conditions in four urban spaces by means of measurements and modelling techniques. Building and Environment, 93, 245-257. https://doi.org/10.1016/j.buildenv.2015.06.028
Achour-Younsi, S., & Kharrat, F. (2016). Outdoor thermal comfort: impact of the geometry of an urban street canyon in a Mediterranean subtropical climate–case study Tunis, Tunisia. Procedia-Social and Behavioral Sciences, 216, 689-700.‏ https://doi.org/10.1016/j.sbspro.2015.12.062
Andreou, E. (2013). Thermal comfort in outdoor spaces and urban canyon microclimate. Renewable energy, 55, 182-188.‏ https://doi.org/10.1016/j.renene.2012.12.040
Azizi, M. M., Aminzadeh, B., & Aghamolaei, R. (2020). An Evaluation of Thermal Performance of Urban Fabrics in Tehran Climate: Implications for Micro Climate-Sensitive Urban Design. Journal of Fine Arts: Architecture & Urban Planning, 25(1), 5-15. 10.22059/jfaup.2020.296175.672397 [In Persian]
Bahrainy, H., & Khosravi, H. (2015). Comparative study of the impact of micro-climate features on urban behaviour patterns, the case of urban spaces of Yazd (warm and dry climate) and Fuman (moderate and humid climate). Journal of Environmental Studies, 41(2), 465-482.  10.22059/jes.2015.54994 [In Persian]
Brozovsky, J., Corio, S., Gaitani, N., & Gustavsen, A. (2021). Evaluation of sustainable strategies and design solutions at high-latitude urban settlements to enhance outdoor thermal comfort. Energy and Buildings, 244, 111037.‏ https://doi.org/10.1016/j.enbuild.2021.111037
Calthrope, P. (2015). Urbanism in the age of Climate Change. (Translated by Bahrainy, H., Hemati, M., Mehrnezhadboora, P.), Tehran: University of Tehran Press.
Delfanian, H., Khakzand, M., Kamyabi, S. (2019). Identifying the Relationship between Vernacular Architecture & Climate through Studying Thermal Comfort Indicators in Nowshahr City. Armanshahr, 11(25 ), 69-79. SID. https://sid.ir/paper/202480/en [In Persian]
Gaber, N., Ibrahim, A., Rashad, A. B., Wahba, E., El-Sayad, Z., & Bakr, A. F. (2020). Improving pedestrian micro-climate in urban canyons: City Center of Alexandria, Egypt. Urban Climate, 34, 100670.‏ https://doi.org/10.1016/j.uclim.2020.100670
Haghighat Naeini, G., Fayaz, R., Bigharaz, B., (2019). Achieving Thermal Comfort in Public Spaces Using a Step-by-step Simulation Process Case Study: A Neighborhood Unit in Imam Khomeini Town, Lar. Naame Memari va Shahrsazi, 11(21 ), 77-100 SID. https://sid.ir/paper/215899/en [In Persian]
He, B. J., Ding, L., & Prasad, D. (2020). Relationships among local-scale urban morphology, urban ventilation, urban heat island and outdoor thermal comfort under sea breeze influence. Sustainable Cities and Society, 60, 102289.‏ https://doi.org/10.1016/j.scs.2020.102289
Heidari, S., Ghaedi, H. (2020). Impact of Coastal Fabric Variables on Climatic Variables in Hot and Humid Regions (Case Study: Bandar Abbas). Olom va Tecnology Mohit Zist. 22(6), 267-278. https://civilica.com/doc/1287363/ [In Persian]
Johansson, E. (2006). Influence of urban geometry on outdoor thermal comfort in a hot dry climate: A study in Fez, Morocco. Building and environment, 41(10), 1326-1338.‏ https://doi.org/10.1016/j.buildenv.2005.05.022
Kim, Y. J., & Brown, R. D. (2021). A multilevel approach for assessing the effects of microclimatic urban design on pedestrian thermal comfort: The High Line in New York. Building and Environment, 205, 108244.‏ https://doi.org/10.1016/j.buildenv.2021.108244
Mahmoud, H., Ghanem, H., & Sodoudi, S. (2021). Urban geometry as an adaptation strategy to improve the outdoor thermal performance in hot arid regions: Aswan University as a case study. Sustainable Cities and Society, 71, 102965.‏ https://doi.org/10.1016/j.scs.2021.102965
Mansi, S. A., Barone, G., Forzano, C., Pigliautile, I., Ferrara, M., Pisello, A. L., Arnesano, M. (2021). Measuring human physiological indices for thermal comfort assessment through wearable devices: a review. Measurement, 109872.‏ https://doi.org/10.1016/j.measurement.2021.109872
Paolini, R., Mainini, A. G., Poli, T., & Vercesi, L. (2014). Assessment of thermal stress in a street canyon in pedestrian area with or without canopy shading. Energy Procedia, 48, 1570-1575.‏ https://doi.org/10.1016/j.egypro.2014.02.177
Sabrin, S., Karimi, M., Nazari, R., Pratt, J., & Bryk, J. (2021). Effects of different urban-vegetation morphology on the canopy-level thermal comfort and the cooling benefits of shade trees: Case-study in Philadelphia. Sustainable Cities and Society, 66, 102684.‏ https://doi.org/10.1016/j.scs.2020.102684
Thravalou, S., & Philokyprou, M. (2021). Urban design considerations in the environmental assessment of vernacular buildings with timber projections (sachnisi): The case of Nicosia's historic center. Frontiers of Architectural Research, 10(1), 176-189.‏ https://doi.org/10.1016/j.foar.2020.11.001
Tsoka, S. (2017). Investigating the relationship between urban spaces morphology and local microclimate: a study for Thessaloniki. Procedia environmental sciences, 38, 674-681.‏ https://doi.org/10.1016/j.proenv.2017.03.148
Wei, R., Song, D., Wong, N. H., & Martin, M. (2016). Impact of urban morphology parameters on microclimate. Procedia Engineering, 169, 142-149.‏ https://doi.org/10.1016/j.proeng.2016.10.017
Wong, P. P. Y., Lai, P. C., Low, C. T., Chen, S., & Hart, M. (2016). The impact of environmental and human factors on urban heat and microclimate variability. Building and Environment, 95, 199-208. https://doi.org/10.1016/j.buildenv.2015.09.024
Yin, Q., Cao, Y., & Sun, C. (2021). Research on outdoor thermal comfort of high-density urban center in severe cold area. Building and Environment, 200, 107938.‏ https://doi.org/10.1016/j.buildenv.2021.107938