چگونگی عملکرد گیاهان در تعدیل پارامترهای موثر بر آسایش حرارتی در فضای شهری نمونه‌ پژوهش: دیوار سبز شهری در تهران

ارتباط انسان و طبیعت و اهمیت بهره‌گیری از این ارتباط در محیط شهری، یکی از مسائلی است که همواره توجه برنامه‌ریزان حوزه‌ فضای شهری را جلب کرده است؛ اما چندی است که انسان با ایجاد تغییرات در شهرها این تعامل حیاتی را به خطر انداخته است. یکی از عوامل موثر در این زمینه، احساس رضایتمندی انسان از شرایط حرارتی است. آسایش حرارتی در فضای باز علاوه بر شرایط اقلیمی، متاثر از محیط مصنوع پیرامون، پوشش‌های به‌کاررفته در زمین، تبخیر گیاهان و سایر عوامل موجود در سایت است. در این پژوهش از میان راههایی که برای ارتقای آسایش حرارتی شهری وجود دارد، بر بهره‌گیری از گیاهان از طریق تعدیل دما و رطوبت تاکید می‌شود. در این پژوهش نخست تاثیر حضور گیاهان در قالب یک نمونه دیوار سبز به‌صورت میدانی ازنظر تاثیر بر دما و رطوبت نسبی تحلیل شد؛ سپس با استفاده از نرم‌افزار envimet یک بلوک شهری موجود با استقرار درختان فرضی و یک بلوک فرضی با اضافه‌کردن پوشش گیاهی شبیه‌سازی شد. براساس نتایج، دمای هوا در نقاط نزدیک به فضای استقرار گیاهان و در فاصله‌ کمتر از 0.5 متر، حدود 0.5 درجه کمتر از سایر نقاط است؛ علاوه بر دما، رطوبت نسبی نیز در این محدوده بیشتر است که از برآیند تاثیر این دو عامل، آسایش حرارتی در میکرواقلیم‌های شهری اطراف گیاهان به‌ویژه در فصول گرم ارتقا خواهد یافت. بررسی انواع گیاهان نیز نشان داد تعدیل دما فارغ از نوع گیاه صورت خواهد گرفت.

Effects of Plants on the Parameters Involved in Thermal Comfort in Urban Space:A Case Study of Urban Green Wall in Tehran City

Abstract:The relationship between man and nature and its importance in the urban environment is one of the issues considered by theorists and planners in the field of urban space for a long time. However, human beings as the basis for this relationship have  jeopardizing this vital interaction by making changes in cities for some time now. One of the significanr in human communication and the redidence in cities is his satisfaction by climate conditions. The outdoor thermal comfort is affected by the built environment, land cover, plant evapotranspiration, and other factors present at the site. In this study, among the ways of promoting thermal comfort in urban space, the use of plants is focused on. In this article, the effects of plants on temperature and relative humidity were firstly analyzed in a case study. Then, using Envimet software, an existing urban block was simulated by placing hypothetical trees and another hypothetical block was simulated as well. According to the results, the air temperature in the places, which were very close to the nearly 50cm plants, was obtained to be almost 0.5◦C lower than other places. In addition, the relative humidity within the studied limits was higher. Therefore, the effects of these two factors on improving the thermal comfort of urban microclimates, especially in hot seasons, could be well evidenced. The assessment of different types of plants also showed that the temperature adjustment could be achieved regardless of plant type. Keywords: plant, thermal comfort, urban space, field study, simulation References: Alexandri E, Jones P. 2008, Temperature decrease in an urban canyon due to green walls and green roofs in diverse climates. Building and Environment; 43:480e93. Baghaei Daemei Abdollah, Maryam Azmoodeh, Zahra Zamani, Elham Mehrinejad Khotbehsara,2018, Experimental and simulation studies on the thermal behavior of verticalgreenery system for temperature mitigation in urban spaces, Journal of Building Engineering 20 (2018) 277–284 Buccolieri, R.; Santiago, J.L.; Rivas, E.; Sanchez, B. Review on urban tree modelling in CFD simulations: Aerodynamic, deposition and thermal effects. Urban Forest. Urban Green. 2018, 31, 212–220 Ca, V. T.; Asaede, T. Abu. E. 1998. Reductions in air conditioning energy caused by a nearby park. Energy and Building. Vol. 29: 8392. Chen, L.; Ng, E. (2012): Outdoor thermal comfort and outdoor activities: A review of research in the past decade. Cities 2012, 29, 118–125. Dunnett, N Kingsbury, c. 2008, Planting Green Roofs and Living Walls, Revised and Updated Edition, Timber Press, Portland, Oregon. Daemeia, A, M Azmoodeh, Z Zamani, E Mehrinejad Khotbehsara, (2018) , &Experimental and simulation studies on the thermal behavior of vertical greenery system for temperature mitigation in urban spaces&, Journal of Building Engineering 20 (2018) 277–284 Elnabawi, M.H.; Hamza, N. A (2020),Behavioural Analysis of Outdoor Thermal Comfort: A Comparative Analysis between Formal and Informal Shading Practices in Urban Sites. Sustainability, 12, 9032. Kobayashi, H. Kai, T. 2005. The use of urban green space to improve the thermal environment. The 2005 world Sustainable Building Conference. 2729 september 2005, Tokyo. Hart, M. A. Sailor, D. J. 2008. Quantifying the influence of landuse and surface characteristics on spatial variability in the urban heat island. Theor Appl climatol, Vol. 94: 397406. Heisler, G.; Walton, J.; Yasilonis, J.; Nowak, D.; Pouyat, R.; Grant, R.; Grammond, S.; Hayde, k. Bacon, G. 2007. Empirical modeling and mapping of belowcanopy air temperatures in Baltimore, MD and vicinity. paper presented at the proceedings of 7th urban environment symposium, 1013 September 2007, Sun Diego. Hoyano A (1988) Climatological uses of plants for solar control on the effects on the thermal environment of a building. Energy and Buildings, 11: 181–9 Holm D (1989) Thermal improvement by means of leaf cover on external walls – a simulation model, Energy and Buildings, 14: 19–30 Hwang, W. H. 2007. Estimation of the Effects of Vegetation on Local Climate Using GIS and Remote Sensing Data. Master of Science Thesis. Marshall university Khalaim, O.; Zabarna, O.; Kazantsev, T.; Panas, I.; Polishchuk, O. (2021): Urban Green Infrastructure Inventory as a Key Prerequisite to Sustainable Cities in Ukraine under Extreme Heat Events. Sustainability, 13, 2470 Gatto, E.; Buccolieri, R.; Aarrevaara, E.; Ippolito, F.; Emmanuel, R.; Perronace, L.; Santiago, J.L.(2020) Impact of Urban Vegetation on Outdoor Thermal Comfort: Comparison between a Mediterranean City (Lecce, Italy) and a Northern European City (Lahti, Finland). Forests 2020, 11, 228 Ifatimehin, O. O. 2007. An assessment of urban heat island of Lokoja town and surroundings using Landsat ETM data. viewed at February 2011, Schrader, S and Boning, M. (2006) soil formation on green roofs and its contribution to urban biodiversity with emphasis on column balans, Pedobiologia, Vol 50, Issue 4, pp. 347356 Taleghani M, Sailor DJ, Tenpierik M, van den Dobbelsteen A (2014) Thermal assessment of heat mitigation strategies: The case of Portland State University, Oregon, USA, Building and Environment, 73: 138150 Taleghani, M. (2018). Outdoor thermal comfort by different heat mitigation strategies A review. Renew. Sustain. Energy Rev. 2018, 81, 2011–2018. T.U.N., Kaluarachichi, Tjoelker M.G., and Pfautsch S.. (2020) :Temperature Reduction in Urban Surface Materials through Tree Shading Depends on Surface Type Not Tree Species& Forests 11, no. 11: 1141. Vo, T.T., Hu, L.(2020), Diurnal evolution of urban tree temperature at a city scale. Sci Rep 11, 10491 Zhang, L.; Wei, D.; Hou, Y.; Du, J.; Liu, Z.; Zhang, G.; Shi, L.(2020),  Outdoor Thermal Comfort of Urban Park—A Case Study. Sustainability 12, 1961.