پديد آورندگان :
مرئي، الهه دانشگاه هنر - دانشكده معماري و شهرسازي، تهران، ايران , فياض، ريما دانشگاه هنر - دانشكده معماري و شهرسازي - گروه معماري و انرژي، تهران، ايران , معماريان، سينا دانشگاه هنر - دانشكده معماري و شهرسازي، تهران، ايران , محمد كاري، بهروز مركز تحقيقات راه، مسكن و شهرسازي، تهران، ايران
كليدواژه :
مصالح پوسته شهر , مصالح پياده راه ها , مصالح خيابان ها , مصالح بام ها , آلبيدو , جزيره حرارتي , دماي سطح
چكيده فارسي :
مصالح قابليت جذب، انباشت و انتقال پرتوهاي خورشيد به جو را دارند. بدين معنا كه مصالح مورداستفاده در پوسته شهر، نقشي كليدي در تغيير خرداقليم شهرها و ايجاد اثر جزيره حرارتي دارد. براي شناسايي تأثير مصالح مختلف پوسته شهري بر افزايش دماي هواي مجاور سطوح، يك مطالعه تجربي بر روي 30 نمونه از مصالح رايج مورداستفاده در پياده‌راه، خيابان و بام در شهر تهران انجام شده است. در اين پژوهش با هدف بررسي تأثير خواص ترموفيزيكي و تابشي مصالح و با بهره‌گيري از ابزارهايي چون ترمومتر تماسي، دوربين مادون‌قرمز و طيف‌سنج، عملكرد حرارتي و نوري نمونه‌ها موردمطالعه قرار گرفت. با استفاده از روش‌هاي آماري، خصوصيات فيزيكي نمونه‌ها چون رنگ، جنس و بافت سطح و اثر هر يك بر تغييرات دماي سطوح به كمك داده‌هاي جمع‌آوري شده مشخص گرديد. نتايج نشان مي‌دهد كه در اكثر نمونه‌ها، بيشينه دماي سطح بالاتر از oC 54 و شاخص بازتاب خورشيدي(SRI) و آلبيدوي كمتر از 50% است كه در افزايش دماي هواي مجاور نقش به‌سزايي دارند. لذا استفاده از مصالح با رنگ روشن و صيقلي و همچنين آلبيدو بالا، به شرط كنترل خيرگي، از مؤثر‌ترين راهكارهاي كنترل افزايش دماي هواي مجاور است. اين مطالعه مي‌تواند در انتخاب هرچه بهتر مصالح مناسب، كاهش اثر جزيره حرارتي و در نتيجه بهبود شرايط آسايش حرارتي در محيط‌هاي خارجي در ايران مؤثر باشد.
چكيده لاتين :
Urban geometry and the materials used in urban fabric play an important role in the microclimate of cities and the mitigation of heat islands. Materials can absorb solar and infrared radiation and scatter the accumulated heat into the atmosphere. The use of large quantities of construction materials such as bricks, concrete, asphalt mixtures, stones, etc. in urban areas, instead of
using natural terrain and green areas, is one of the main causes of the Urban Heat Island (UHI). Urban surface materials, as a
major interface element, have a significant role in improving microclimate and comfort conditions and reduction of heat gains.
An experimental study was carried out to evaluate the effect of various urban surface materials on the potentiality of
increasing ambient air temperature in Tehran. 30 conventional paving and roofing materials, which are being used in Iran,
were examined during the summer of 2014. The thermophysical properties and solar reflectance values of these materials
were measured, in order to determine the impact of the thermal and optical performance of the samples under study on
ambient and surface temperatures and their effect on UHI in the hot-arid climate of Tehran. A statistical analysis using
F-ANOVA and t-test was performed to identify the effect of physical properties including surface color, surface roughness,
and construction of these materials. A spectrometer and an infrared camera were used to quantify the surface reflection
and emissivity of the materials. Samples were placed on an extruded polystyrene (XPS) layer -except grass and asphalt
that existed in the site- to eliminate the heat transfer between the ground and the samples. The surface temperature of
the materials was hourly measured using T type contact thermocouples for 24 days. Also, temperature fluctuations were
studied in relation to outdoor temperature. The highest thermal changes in the materials mostly occur in the mid-day, when
outdoor temperature and solar radiation are at their maximum. Most of the analysis was carried out between 11:00 am. and
05:00 pm. The results show that dark-colored surface materials have more tendency to absorb solar radiation compared
to the smooth and light-colored ones and were warmer. Some materials were warmer than ambient air temperature which
is related to the physical, optical, and thermal properties of the samples. Comparative analysis of current pavement and
roofing materials used in Tehran showed that most surface temperatures of materials surface are more than 54 ˚C and the
Solar Reflectance Index (SRI) and albedo are lower than 50% that will lead to higher surface temperatures. According to the
measurement results and the increase of UHI in Tehran metropolitan area due to the density of the city, the use of light color
and smooth materials with high solar reflectance, regardless of their shape, and more greenery covers are more appropriate
for Tehran. It is also an effective strategy in mitigating urban heat islands, decreasing cooling load during summer, and
improvement of thermal comfort in urban spaces, provided that nuisance glare is prohibited.
