Energy Conservation Potential of an Extensive Green Roof in Iran for One Year Duration
محورهای موضوعی : مجله گیاهان زینتی
Navid Vahdati
1
(PhD Student, Department of Horticultural Science and Landscape, Ferdowsi University of Mashhad, Iran)
Ali Tehranifar
2
(Professor, Department of Horticultural Science and Landscape, Ferdowsi University of Mashhad, Iran)
Fatemeh Kazemi
3
(Assistant professor, Department of Horticultural Science and landscape, Ferdowsi University of Mashhad, Iran)
کلید واژه: Season, Green roof, Plant variation, Temperature fluctuation, Thermal performance,
چکیده مقاله :
The temperature of cities continues to increase because of the heat island phenomenon and the undeniable climatic change. The observed high ambient temperatures intensify energy problems in cities, deteriorates comfort conditions, put in danger the vulnerable population and amplify the pollution problems. There are some suggested ways to reduce these issues, among them vegetated roofs are shown to be promising. This study describes energy consumption performance of an extensive modular type green roof with different plant selections using a randomized complete design in Mashhad, Iran. Nine species from three major taxonomic and functional plant groups (grasses, ground covers and sedums) namely (Agropyron cristatum, Festuca aurundinacea, Festuca ovina, Potentilla sp., Frankenia thymifolia, Vinca minor, Sedum acre, Sedum spectabile, Carpoboratus edulis) were selected. Temperature fluctuations during four seasons were recorded with three replicates. Experimental trials with growing beds without plants (bare roofs) were also used as controls. Small hand manual thermometers were placed in each module (box) and air temperature was also recorded. The results showed very significant temperature differences between the green and bare roof modules. Larger plants with higher biomasses kept temperatures more stable. Thermal comfort and energy saving was achieved using green roofs in this research and it could be well used in a large scale for growing cities and population energy requirements.
دمای هوا در شهرها به دلیل رخداد پدیده جزیره گرمایی و تغییر اقلیمی اجتناب ناپذیر، به­طور پیوسته رو به افزایش است. این افزایش دما منجر به ایجاد مشکلاتی چند از جمله کمبود انرژی در شهرها، برهم زدن شرایط آرامش، ایجاد آسیب برای شهروندان و تشدید آلودگی­ها شده است. راه­های گوناگونی برای کاهش این نگرانی­ها و مخاطرات وجود داشته و از این میان بام­های سبز بسیار کارا و موثر نشان داده­اند. این تحقیق به بررسی عملکرد ذخیره انرژی (تغییرات دمایی) در یک بام سبز با پوشش­های گیاهی متنوع در ایران و شهر مشهد پرداخته است. 9 گونه گیاهی از سه دسته مهمی که معمولا در بام سبز به کار می­روند (گراس، گیاهان پوششی و سدوم­ها) (Agropyron cristatum, Festuca aurundinaceae, Festuca ovina, Potentila sp., Frankinia thymifolia, Sedum acre, Sedum spurium, Carpoboratus edulis و Vinca minor) گزینش و تغییرات دمایی در 4 فصل متوالی (پاییز، زمستان، بهار و تابستان) در قالب یک آزمایش کاملا تصادفی با 3 تکرار ثبت گردید. یک واحد آزمایشی بدون پوشش گیاهی (بام بدون پوشش) نیز به عنوان تیمار شاهد در نظر گرفته شد. دماسنج­های کوچک دستی برای اندازه­گیری دما در هر جعبه قرار داده شد. نتایج حاکی از اختلاف معنی­دار بین بام­ سبز و بام بدون پوشش با در نظر گرفتن تغییرات دماست (P < 0.01). مطابق پیش بینی، گیاهان با اندازه بزرگتر و وزن زیست توده بالاتر درجه حرارت را با ثبات بیشتری نگهداشت و به ترتیب دماهای بالاتر و پایین­تر کمتری در فصول گرم و سرد سال در آن­ها مشاهده گردید. آسایش دمایی و کاهش مصرف انرژی می­تواند با استفاده از بام سبز در سطح گسترده برای نیازهای رو به فزونی شهرها و جمعیت شهروندی، تامین گردد.
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