تحلیل بررسی آسایش حرارتی در فضاهای باز شهری در فصل تابستان با استفاده از شاخص ppd (مطالعه موردی: پیاده‌راه رود کنار خرم آباد)

امروزه بحث آسایش حرارتی به عنوان یکی از عوامل مهم در کیفیت فضا های شهری در کنار عوامل کالبدی مطرح گردیده است در واقع کیفیت فضاهای شهری برای استفاده شهروندان مهم بوده و بایستی به آن توجه شود. اما به دلیل تاثیر عوامل گوناگون در فضاهای باز شهری که بر روی آسایش حرارتی کاربران تاثیرگذار است و کمبود مبانی مدون در این زمینه موجب دشواری تشخیص و تامین نیازهای اقلیمی در یک محدوده شهری برای طراحان گردیده است. پژوهش حاضر با در نظر گرفتن بحث آسایش حرارتی در فضای پیاده راه شهری، به بررسی عوامل اقلیمی و محیطی در محدوده مورد نظر که در این پژوهش شهر خرم‌آباد و در حریم قلعه فلک الافلاک واقع گردیده است، پرداخته و از طریق کاربرد تکنیک شبیه‌سازی رایانه‌ای با استفاده از نرم افزار انوی متa به بررسی یکی از شاخص‌های آسایش حرارتی بنام درصد نارضایتی پیش‌بینی شدهb در نقاط مختلف مسیر پیاده راه طراحی شده می‌پردازدکه در بررسی نتایج بدست آمده مشخص میشود که عواملی نظیر انتخاب جهت مسیر حرکت پیاده‌راه، ساعت پیاده روی، عرض پیاده‌راه، وجود درختان، سایه و آب همچنین برخی ویژگی های کاربران نظیر نرخ متابولیک، نرخ فعالیت، نرخ پوشش در میزان آسایش حرارتی تاثیرگذار بوده است. 

investigation of ppd index in thermal comfort of urban open spaces in summer (case study: sidewalk in riverside, khorramabad city)

introduction: regarding the importance, although it is a significant task to determine all the influencing factors on the riverbanks, thermal comfort is much more effective. for this reason, the balanced relationship between the presence of people and the enjoyment of thermal comfort can play an effective role in creating a public and open urban space. in this research, by examining the thermal comfort on the urban sidewalk and knowing the factors that affect the thermal comfort in the open space, it is possible to achieve an urban space that citizens are willing to use, and this is the necessity of this research and its purpose. investigating thermal comfort in riverside sidewalks is to find the factors that create the greatest impact between humans and the environment in urban open spaces and ultimately increase theattendance rate in these spaces.methodology: the current research aims to investigate the climatic and environmental factors in the thermal comfort of the users of the khorram abad city sidewalk by using water levels, the shade of plantain trees, and vertical canopies on the sidewalk. after reviewing the history of thermal comfort studies in urban open spaces, which is based on library studies and includes reading texts, and using articles, in thermal comfort, the ppd index, which is a valid index in thermal comfort, was selected and then using influence of the selected parameters on the degree of a thermal sensation of people has been investigated using the analytical method.results: in an analytical approach, the specifications of the mahoni table for khorramabad city show the existence of favorable thermal comfort conditions in the three seasons of may, october, and november of the year. therefore, it is expected that there will be unfavorable thermal comfort in the remaining nine months, i.e., april, june, july, august, september, december, bahman, and march. in this way, we can say that it is cold almost 45% of the time of the year and mechanical heating shouldheat the space inside the building. also, 30% of the time of the year, the weather is hot and mechanical ventilation and cooling should be used. the total figures for hot and cold times of the year show comfortable conditions exist only in 25% of the times of the year for khorramabad city.conclusion: the comparative study shows that in the middle of summer there is no thermal comfort inthe open space because of the heat of the air (44.2°c) during the day (from 9:00 to 19:00), and only in the early hours of the day until 9:00 and thermal comfort is possible from 19:00 onwards by observing the coverage and activity rate and using green corridors. it is also clear that men have better conditionsthan women in terms of physiology and a lower coverage rate in this situation. the investigation carried out with the help of envi met software shows that on august 1, 2018, there is thermal comfort in limited hours of the day, so from 10:00 to 19:00 there is no thermal comfort because of the high temperature inthe outdoor space and the percentage of thermal dissatisfaction index it is at its highest value, i.e. 95%, until sunset, which is at 6:26 p.m. on this day, and from 7:00 p.m. to 9:00 p.m., when the thermal simulation was performed, because of the absence of sunlight, the temperature decreased and the percentage of the thermal dissatisfaction index also decreased.