نوع مقاله : مقاله پژوهشی

نویسندگان

1 عضو هیئت علمی دانشگاه علم و صنعت ایران گروه شهرسازی

2 دانشگاه علم و صنعت ایران

3 عضو هیئت علمی دانشگاه علم و صنعت ایران گروه معماری

4 مدرس معماری و مرمت دانشگاه علم و صنعت ایران

چکیده

شهرها طی بیش از یک قرن تغییرات اساسی که در فعالیت­ها و کالبد آنها رخ داده، ارتباط حیاتی خود را با طبیعت از دست داده­اند. در سال­های اخیر توسعه شهرنشینی و پیوستن روستاها به کلانشهرها موجب از بین رفتن بسیاری از پوشش­های گیاهی این مناطق شده است. محله ازگل از جمله محلات شمال تهران است که بخش عمده­ای از فضای سبز آن در فرایند توسعه از بین رفته و کیفیت فضایی در کانون­های متمرکز آن کاهش یافته است. با توجه به اثر گیاهان در ایجاد شرایط آسایش، این مقاله با هدف ارتقای کیفیت فضاهای عمومی و افزایش آسایش حرارتی در مراکز محله به دنبال یافتن رابطه بین سطوح سبز با میزان کاهش دما در گرم­ترین روز سال است. مقاله با راهبردی ترکیبی متکی بر استدلال منطقی و سنجش نرم­افزاری به مطالعه یک سایت در محله ازگل تهران در دو وضعیت موجود و حالت بهینه طراحی پرداخته است. داده­های وضع موجود با برداشت­های میدانی و اطلاعات خرداقلیم در وضعیت دوم که با افزودن گیاهان به فضا مورد بررسی قرار گرفت، با شبیه­سازی کامپیوتری به دست آمد. در نهایت شرایط آسایش با مدل PMV سنجیده شده تا اثر دقیق گیاهان بر عناصر خرداقلیم مشخص شود و دو حالت باهم مقایسه شدند تا تأثیر طراحی با گیاهان در ارتقای کیفیات محیطی مشخص شود. معیارهای ارزیابی، دما و رطوبت نسبی است که محاسبات با اولویت­دهی به پیاده، در ارتفاع 1.65 متری انجام شده است. یافته­های به دست آمده از این مطالعه حاکی از این است که با اختصاص درصد کمی از فضای شهر به سبزینگی تا حد زیادی می­توان شرایط خرداقلیم را بهبود بخشید. محاسبات رایانه­ای نشان داد به ازای افزودن هر مترمربع فضای سبز در موقعیت مکانی مورد مطالعه، 71/3 برابر آن به محدوده آسایش اضافه می­گردد. همچنین در نمونه مورد بررسی، با ثابت نگه داشتن رطوبت نسبی می­توان 1.5 تا 2 درجه از گرمای هوا کاست. با توجه به این که گرمایش جهانی در صد سال اخیر حاصل یک درجه اضافه شدن به دمای کره زمین است، نتایج مقاله قابل توجه خواهد بود. به بیانی با تعمیم نتایج در کل محله و در مقیاسی بزرگتر، اثربخشی آن چشمگیرتر خواهد بود.

کلیدواژه‌ها

موضوعات

عنوان مقاله [English]

Investigation of Thermal Effect of Plants in Urban Spaces by PMV Model (Case Study of Ozgol neighborhood of Tehran)

نویسندگان [English]

  • seyed majid mofidi shemirani 1
  • seyedeh maryam hoseini 2
  • haniyeh sanayeiyan 3
  • gholamreza japalaghi 4

1 iran university of science and technology

2 Iran University of Science and Technology

3 iran university of science and technology

4 iran university of science and technology

چکیده [English]

Throughout the past century, cities have lost their vital connection with the nature due to the fundamental changes in their functions and physical forms. The development of urbanization and attachment of villages to metropolises in recent years have led to destruction of vegetation in these regions. The importance of identifying the effects of cities on their climates can be indicated only through accurate research and quantitative assessment. The overall increase in air temperature as a result of urbanization is 1-3 degrees Celsius. In stable climatic conditions, however, the air temperature difference between urban and suburban areas can be as high as 10 degrees Celsius.
Increasing the amount of vegetation, planting trees, and developing ecological networks are some of the effective passive methods available for improvement of microclimates. Similar methods have been used in the ancient cities of Iran, where the temperature inside the cities has always been lower than that of the surrounding areas due to the utilization of a special type of urban planning which has been capable of providing appropriate climatic conditions at micro scale by controlling climatic elements.
Ozgol is one of the northern neighborhoods of Tehran, where green spaces have diminished as a result of the development process and space quality at the centralized focal points has decreased. This study attempted to identify the relationship between green areas and temperature decrease on the hottest day of the year to help improve the quality of the public spaces and increase thermal comfort at the focal points of the neighborhood.
This research used a hybrid methodology based on logical reasoning and software-assisted assessment to study a site in the Ozgol neighborhood under two conditions: current status and optimal design. The data on the current situation of the neighborhood were obtained by field measurements, and those on the latter situation were obtained via computer simulation and addition of plants to the area. Then, the PMV model was used for assessment of the comfort conditions and specification of the exact effect of plants on microclimate elements. The two conditions were compared, and the impact of urban design with plants on environment quality was evaluated. The evaluation criteria included temperature and relative humidity. The measurements were made at a height of 1.65 meters to prioritize pedestrian comfort. The findings suggested that allocation of a low percentage of city space to greenery can greatly improve microclimatic conditions. The computations indicated that every square meter of green space added to the area under study would expand the comfort zone by 3.71 times. The results also demonstrated that retention of the amount of relative humidity can reduce air temperature by 1.5-2 degrees Celsius.
The findings of this study highlighted the significance of preserving the current green spaces over the neighborhood and the necessity of avoiding any change in the land use of the remaining gardens (about 6,000 m2 in the 4-hectare area of the site). The computations also showed that addition of the existing green spaces over the area by 2.69% can expand the area within the range of thermal comfort to twice as wide as the pre-intervention area. One the other hand, the issue of global warming, the 1-degree rise in the world’s temperature during the past century, highlights the value and significance of this 1.5-degree temperature decrease. Thus, it is possible to make significant changes through extension of the results of this study to a larger scale to involve the entire city.

کلیدواژه‌ها [English]

  • Urban microclimate
  • plants
  • Ozgol Neighborhood
  • Envi-Met
  • Thermal comfort

Ashrae, (2013), ANSI/ASHRAE Addendum h to ANSI/ASHRAE Standard 55-2010, Thermal Environmental Conditions for Human Occupancy, American society of heating, refrigerating and air conditioning engineers, INC, Tullie Circle, NE  Atlanta GA

Baft-e-Shahr Consulting Architects Urban Planners, (2007), Detailed plan of Tehran Municipality's District One, Tehran. [in Persian]

Baklanov, A, Grimmond, C.S.B , Carlson, D, Terblanche, D, Tang, X, et al. (2018). From urban meteorology, climate and environment research to integrated city services. Urban Climate 23. 330-341.

Ren Chao, Yan-yung, Ng Edward, Lutz, Katzschner. (2011). Urban climatic map studies: a review. INTERNATIONAL JOURNAL OF CLIMATOLOGY. Int. J. Climatol. Published online in Wiley Online Library. 2213-2233

Elwy, Ibrahim, Ibrahim, Yasser, Fahmy, Mohammad. (2018). Outdoor microclimate validation for hybrid simulation workflow in hot arid climates against ENVI-met and Field measurements. 5th International Conference on Energy and Environment Research. 29-34

Gherraz, H, Guechi, I and A Benzaoui. (2018). Strategy to Improve Outdoor Thermal Comfort in Open Public Space of a Desert City, Ouargla, Algeria. 9th International Conference on Environmental Science and Development-ICESD. IOP Conference Series: Earth and Environmental Science, Volume 151, conference 1

Hai, Ye, Feng, Qian. (2018). Thermalscape of Ecological City and its Visualized Evaluation. CUE2018-Applied Energy Symposium and Forum 2018: Low carbon cities and urban energy systems, Shanghai, China. 1139-1144

 Herath, H.M.P.I.K, Halwatura, R.U, Jayasinghe, G.Y. (2018). Modeling a Tropical Urban Context with Green Walls and Green Roofs as an Urban Heat Island Adaptation Strategy. 7th International Conference on Building Resilience; Using scientific knowledge to inform policy and practice in disaster risk reduction, Bangkok, Thailand. 691-698.

Hosseini, Soheila, (2010), Description of Azgol neighborhood, Andisheh Saraye Shahr Institute, Tehran Municipality District 1 website. [in Persian]

Hou, Tuoyu, Lu, Ming, Fu, Jingwan. (2017). Microclimate perception features of commercial street in severe cold cities. 9th International Conference on Sustainability in Energy and Buildings. Chania, Crete, Greece. 528–535

Jarić, Marko, Budimir, Nikola, Pejanović, Milica and Igor Svetel. (2013). A REVIEW OF ENERGY ANALYSIS SIMULATION TOOLS. 7th International Working Conference ’’Total Quality Management – Advanced and Intelligent Approaches’’, 3rd – 7th June, 2013. year, Belgrade, Serbia. 103-110

     Karamirad, Sina, Aliabadi, Mohammad, Habibi, َAmin, Vakilinejad, Roza, (2018), Measuring the Impact of Vegetation on Pedestrians Thermal Comfort Conditions, Anjoman Elmi Memari va Shahrsazi Iran journal, Volume 8, Issue 14, Pages 185-196. [in Persian]

khalife gholi, aleme (2017), simulating the wind effect in designing the form of urban open spaces in order to improve environment comfort (case study: Sanglaj neighborhood in Tehran), master ofurban design, Department of Urban Design, Tehran Art University, Tehran. Iran. [in Persian]

Lai, Xin, Tang, Yang, Li, Lei, Chan, PakWai, Zeng, Qingfeng. (2019). Study on microclimate observation network for urban unit: A case study in a campus of Shenzhen, China. Physics and Chemistry of the Earth. 117-124.

Lenzholzer, Sanda. Klemm, Wiebke and CarolinaVasilikou. (2018). Qualitative methods to explore thermo-spatial perception in outdoor urban spaces. Urban Climate. Volume 23, Pages 231-249

LI, BEIDI. (2017). Use of Building Energy Simulation Software in Early-Stage of Design Process, Degree Project No. 459, KTH Royal Institute of Technology Division of Building Technology, Department of Civil Engineering and Architecture. Stockholm, Sweden

LIU, Shuyu, SONG, Daifeng, YU, Bo. (2017). The Objective and Methodology of Urban Climate Map for the City of Xiamen. International High Performance Built Environment Conference – A Sustainable Built Environment Conference (SBE16). iHBE. 462-470.

Mexia, Teresa, Vieiraa, Joana, Príncipea, Adriana et al. (2018).Ecosystem services: Urban parks under a magnifying glass. Environmental Research 160. 469–478

Mohammadi, Hossein, (2012), Urban Meteorology, University of Tehran Press, Tehran. [in Persian]

Rezazadeh, Razieh, Aghajan Beiglou, Emad, (2011), A New Massing Pattern for Row Housing A Comparison Between Two Massing Types of Residential Blocks Through Thermal Comfort, nameh memari va shahrsazi journal, Volume 4, Issue 7, Pages 165-184. [in Persian]

Toparlar, Y, Blocken, B, Maiheu, B, et al. (2018). Impact of urban microclimate on summertime building cooling demand: A parametric analysis for Antwerp, Belgium. Applied Energy 228. 852–872

Vadodaria, Keyur H. (2014). Thermal Comfort in UK Homes: How suitable is the PMV approach as a prediction tool? A Doctoral Thesis Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University. UK.

www.envi-met.com. 10/30/2018