ارزیابی اثر شاخص هندسی خیابان (H/W) برعملکرد حرارتی مسکن (نمونه مورد مطالعه: آپارتمان های مسکونی همدان)

پیوند بین هندسه معابر شهری (h/w) و مصرف انرژی ساختمان، تعامل پیچیده ای بین عوامل اقلیمی، الگوهای مکانی، نحوه قرارگیری فضاهای باز و همجواری ساختمان هایی است که آنها را تشکیل می دهند.  این تحقیق، با استفاده از مفهوم خرد اقلیم ایجاد شده متاثر از هندسه معابر شهری به بررسی عملکرد حرارتی ساختمان های مسکونی شهرهمدان پرداخته است. ارزیابی اثر هندسه معابر شهری(h/w)  بر میزان مصرف انرژی، هدف اصلی است. در این مطالعه مجموعه جامعی از شبیه سازی های حرارتی مبتنی بر آب و هوای منطقه همدان و تحلیل آماری، برای بررسی چگونگی تاثیر تغییرات ضابطه ارتفاع نسبت به عرض معبر بر میزان مصرف انرژی انجام شده است. روش تحقیق به صورت ترکیبی از روش های کیفی و کمی(داده های عددی شبیه سازی) است. در مرحله شبیه سازی برای شناخت تاثیر(h/w)، بر میزان مصرف انرژی دو حالت در نظر گرفته شده است. ابتدا برای بررسی اثر شاخص عرض معبر، ارتفاع ثابت و عرض معبر متغیر و سپس برای بررسی شاخص ارتفاع، عرض معبر ثابت و ارتفاع متغیر در مدلسازی ها در نظر گرفته شده و در تحلیل یافته ها از روش های آماری، ضریب همبستگی، مقایسه با مدل مرجع و رگرسیون چندگانه بهره گرفته شده است. نتایج بیان می دارد که در تمام قطعات مسکونی الگوهای شمالی، بین (متغّیر(6الی36متری)w/ثابتh) و میزان انرژی سالانه، رابطه همبستگی مستقیم و با شدت زیاد و در الگوهای جنوبی، بدون همبستگی است. همچنین بین (ثابتw/متغیر(3الی10طبقه)h) و انرژی سالانه در قطعات شمالی، همبستگی مستقیم و در قطعات الگوهای جنوبی رابطه همبستگی معکوس ولی با تاثیر بسیار کم برقرار است. بنابراین شاخص هندسی معابر شهری در الگوهای شمالی موثر بوده و افزایش ارتفاع با افزایش فاصله افقی بین ساختمان ها در کاهش مصرف انرژی تاثیرگذار است. هرچه مقدار شاخص ((h/w در معابر شهری اقلیم سرد همدان عدد کمتری باشد(دره های کم عمق)، با افزایش جذب تابش خورشیدی، میزان مصرف انرژی ساختمان کاهش می یابد. با تحلیل رگرسیون چندگانه مشخص شد، شاخص های هندسی ((h/w و مقدار سطوح درمعرض آفتاب(ssu) و سایه(ssh) نسبت به زیربنا(a) و سطح کل(s)، بیشترین تبیین کننده مصرف انرژی در الگوهای قطعات شمالی هستند. الگوی پیشنهادی (تغییر در استقرار سطح اشغال الگوی اول) بهینه ترین عملکرد حرارتی را با کاهش 42.9 درصد انرژی سرمایشی و 4.73 درصدی انرژی نهایی دارد.

Examining the effect of Geometric index of Street (H / W) on the thermal performance of housing (Case Study: Hamedan residential buildings)

HighlightsThe street geometry index (H/W) is highly effective on the thermal performance of residential buildings.The lower the value of the index (H/W) on the streets of a coldclimate city, the lower the energy consumption of the building.Changing the pattern of occupancy level of an urban building, to reduce the level of shadow and increase the level of solar radiation wall, improves thermal performance.Increasing the depth of the yard in the southern pattern of the city of Hamadan, Iran reduces the consumption of thermal energy in a building. IntroductionThe relationship between building density and energy consumption involves a complex interaction between climate factors, location patterns, the way urban open spaces are located, and the adjacency of the buildings of which they are composed. Therefore, this study investigated the thermal performance of residential buildings based on the patterns of residential blocks in Hamadan Province, Iran using the concept of minor climate and thermal islands influenced by density regulations. It aimed to evaluate the effect of these regulations on energy consumption. A comprehensive collection of thermal simulations were conducted based on the climate of Hamadan and a statistical analysis for examination of the effect of height on the energy consumption resulting from increased urban density. Theoretical FrameworkA criterion used for measurement of the energy consumption of buildings is the microurban climate resulting from the density regulations (H/W).  These regulations can affect the access of buildings to sunlight and, thus, the energy performance of buildings. Density regulation indices include two categories: middlescale and microscale. The middlescale category involves an H/W criterion for measurement of the impact of the outdoor environment. The microscale category involves criteria for changes in the building volume geometry, including the surfacetovolume ratio (S/V), ratio of surface exposed to direct sunlight to total surface (Ssn/Ssh), shadow area (Ssu/Ssh), substructure (Ssu/A), volume (Ssu/V), and ratio of window surface to the total wall surface (WSR), which changes as height varies. Methodology The methodology involved a combination of qualitative and quantitative methods. In the simulation stage, two modes were considered to specify the effect of H/W on energy consumption. First, fixed height and variable street width were considered in the modeling for examination of the effect of the street width index, and fixed street width and variable height were then considered for examination of the height index. For analysis of the findings of the statistical methods, correlation, analysis of variance, and multiple regression were used.The relationships between energy consumption and the variable of street width and each of the indicators of the variable of height were investigated with the Pearson correlation coefficient. For investigation of the simultaneous effect of all the indices of the independent variable on the dependent variable (energy consumption), multiple regression analysis was used to specify which geometric factor exhibited the greatest impact on energy consumption. Analysis of variance was used for comparison and evaluation of the mean differences between the groups.For validation, two methods were used: experimental (involving field measurements) and comparative (involving a comparison of the results of different software). Results and DiscussionThe results obtained from the correlation analysis revealed that there is a close direct relationship in all residential blocks of northern patterns between H(fix)/W(6m36m) and annual energy consumption, while there is no correlation in southern patterns. The relationship between H(4f10f)/W(fix) and annual energy is direct in northern patterns but inverse and slightly effective in southern patterns.As the H(fix)/W(6m36m) ratio decreases, cooling energy consumption increases sharply (inverse correlation), and heating and total energy consumption decrease sharply (direct correlation). In this analysis, energy savings are greater on a wider street than on a narrower street, and fixedheight buildings exhibit lower annual energy consumption on a wider street.Positive correlation (high intensity) and negative correlation with heating energy (low intensity) is established between the geometric characteristics of residential parts (S/V, Ssu/S, Ssu/V, Ssu/Ssh, and Ssn/A) and cooling energy consumption. Wider streets receive more sunlight than narrower ones, so those with lower geometric indices exhibit better thermal performance and greater reduction of heating energy consumption. ConclusionBuilding density and its indices are influential in northern patterns, and increase in height and pathway width contributes to the reduction of energy consumption. Therefore, the geometric index of an urban street is effective in northern patterns, and a rise in height through an increase  in the horizontal distance between buildings affects the reduction of energy consumption. However, the value of the index (H/W) is lower on the urban passages of the cold climate of Hamadan (deep urban valleys), and the energy consumption of the building decreases as the absorption of solar radiation increases. Multiple regression analysis showed that the most indicative energy consumption factors in the patterns included the geometric index (H/W), the number of sunny surfaces (Ssu), the ratio of shadow (Ssh) to the substructure (A), and total surface area (S) . The proposed model (involving a change in the occupancy level of the initial model) exhibited the most optimal thermal performance with decreases by 42.9% in cooling energy and by 4.73% in total energy.AcknowledgmentThe article has been derived from the Ph.D. thesis entitled &Determination of housing deployment pattern considering the influence of climate factors on the inside thermal comfort whit an energy management approach (case study Hamedan)&, which has been defended by the first author under the second author’s supervision and the third author’s advisory at the Qazvin Branch, Islamic Azad University.