Urban Planning
HOJJAT GHIYASVAND; mohamadjavad saghafi; hossein medi
Abstract
Highlights
-The 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 cold-climate city, the lower the energy consumption of the building.
-Changing the pattern of occupancy level of an urban ...
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Highlights
-The 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 cold-climate 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.
Introduction
The 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 Framework
A criterion used for measurement of the energy consumption of buildings is the micro-urban 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: middle-scale and micro-scale. The middle-scale category involves an H/W criterion for measurement of the impact of the outdoor environment. The micro-scale category involves criteria for changes in the building volume geometry, including the surface-to-volume 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 Discussion
The 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(6m-36m) and annual energy consumption, while there is no correlation in southern patterns. The relationship between H(4f-10f)/W(fix) and annual energy is direct in northern patterns but inverse and slightly effective in southern patterns.
As the H(fix)/W(6m-36m) 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 fixed-height 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.
Conclusion
Building 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.
Acknowledgment
The 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.
Urban Architecture
Amir Hossein Farshchian; Azita Balali Oskuei
Volume 4, Issue 15 , August 2015, , Pages 53-68
Abstract
The present study is based on the analysis of perceiving geometry aiming at explaining, analyzing and displaying the geometry system of urban development according to different periods and the factors affecting it. Cities are formed from the crowds gathered along rivers and ...
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The present study is based on the analysis of perceiving geometry aiming at explaining, analyzing and displaying the geometry system of urban development according to different periods and the factors affecting it. Cities are formed from the crowds gathered along rivers and caves based on perceived relationships, including the requirements of human survival, and are developed according to the needs of people living in them. The most important issue in this system is the type of organization that bonds these parts to urbanism issues and controls them. The main background and hidden relationship in urbanism system is perceiving geometry. It is a factor that systematizes the principles associated with subjectivities in relation to itself beyond visual perception and identifiable mathematical relations. The main research hypothesis and question presented is how cities are developed based on its perceiving geometry and if this type of geometry is effective in other general and specific subjects such as area and area centers. This paper is based on survey-based research, phases of which include 1. defining this system and its performance; 2. studying perceiving geometry and its effects on the formation of Hamadan as a case study; 3. research literature and analysis of information and documents; 4. detailed description of the main periods and parts of the city; 5. analyzing and displaying graphics, images, and factors affecting the formation and geometry of the city and green areas (centers of districts in Hamadan); 6. identifying how the physical structure of the city is achieved, consolidated and continued based on perceived geometry 7. research results 8. strategies to maintain and renovate the geometry according to time and place; and 9. summary and description of the formation and development of the original geometry. Hamadan has ten main periods of the city development based on the most significant changes in the urbanism system: 1. geometry and basic needs; 2. geometry and security vacuum; 3. geometry and government rule; 4. geometry and Islam; 5. geometry and wars 6. geometry and the notable presence of Shiites 7. geometry and machine 8. geometry and urbanism without geometry; 9. geometry and the increase of urban territory, 10. geometry and machinist. Since the early period, six main factors overshadowed this geometry from the smallest urban cell (house) to green spaces and the whole of the city: accessing water, food, green spaces, being with others, security and livelihood. At present, the remaining green spaces of this perceiving geometry system is that it apparently has no causality and order, but internally it has the most precise causal relationship so that the semantic adaptability of these issues will be manifested by analyzing this issue in the different periods of the city’s development. The basic strategies that result from this research include: 1. detection of the type of process of change according to the geometry of growth and factors affecting it and how to respond in any successful period; 2. examination of the stoppage time and sidelining its correct and appropriate procedure along with the reasons regulating this issue; 3. identification of the type of geometry which, after stoppage period, has taken the procedure and managed the changes; 4. Finally, the adaptation of the type of the main perceiving geometry with the present geometry and entering the modern components in achieving a geometry in accordance with all aspects of present life. This geometry can be the most desirable turning point in this regard with a reforming view to the future of desirable architecture and urban development that can be turned to optimizing and renovating green space according to this type of recognized perceiving geometry.
