جستجوی مقالات مرتبط با کلیدواژه « عملکرد حرارتی » در نشریات گروه « هنر و معماری »

In a cold climate, it is necessary to correctly determine the window geometry parameters in order to access sunlight and improve thermal performance. The window is one of the main factors that can increase the demand for cooling energy in summer and reduce heating energy in winter. Therefore, the goal is to investigate the effect of window geometry parameters (WWR, U, SHGC, Shading) on energy consumption, in order to determine the optimal window level of the cold climate urban housing of Hamedan city. The ratio of the surface of the window to the wall and its geometric parameters, as an independent variable, and the amount of energy consumption, is a dependent variable.

The type of research is quantitative and based on the numerical data of the window-to-wall surface (WWR) and energy simulation, and statistical methods have been used in the analysis of the findings. In the data analysis, Pearson's correlation coefficient analysis, variance comparison analysis and follow-up tests were used to determine the relationship between the variables and determine the optimal level (WWR). This study in four stages; Investigating the window-to-wall surface ratio (WWR) of traditional houses, the effect of the WWR of the north and south facades of contemporary housing on building energy, the optimization of WWR due to variables (U, SHGC, SHADING) and the determination of the optimal level have been carried out.The statistical population of this research is in the first part of the selected houses of traditional housing in Hamadan city and to simulate contemporary housing, of the northern and southern parts in the new texture (conventional linear pattern) with an area of 240 square meters in each plot.

the results showed that; The southern front of traditional housing has 55.69% more glass wall surface than the north-facing front. In the contemporary context of Hamadan city, adding windows to the south-facing walls reduces the heating, lighting and final energy, and the north-facing walls increase the cooling, heating and final energy. The south-facing front has a better thermal performance than the north-facing front with a decrease in final energy (-21.55%). In cold climate, the lower the value of U and SHGC, the lower the energy consumption and the type of relationship is direct. For the north face, shading has no effect on energy consumption. But for the southern front, horizontal and combined fixed shading are effective and reduce cooling energy and increase heating energy, so to prevent the increase of heating energy due to the creation of fixed shading, movable shading can be used, Or it is better to reduce the amount of heating energy consumption by increasing the vertical distance of the awning from the top of the window.

On the south front, the optimal window-to-wall level equal to 60% WWR has a final load reduction of -18.52%, and on the north facing front, WWR = 40% has a final load reduction of -8.38%. Based on the results, a revision proposal has been presented in Appendix 10, Topic 19 of the National Building Regulations.

The efforts to reduce energy consumption, and improve energy performance in buildings, have received much attention in the field of construction, coinciding with the energy crisis in the world. Proper design and construction of building elements and components can reduce energy consumption, reduce negative impacts on the environment and save money throughout the life cycle of the building. The window is usually the façade element with the lowest thermal resistance and the thinnest component with the highest thermal conductivity in the building. Under standard conditions, windows and ventilation are two separate systems, that the lack of a proper management system can increase energy consumption in the building. In this study, the use of airflow window was introduced as a suitable solution and a passive method to reduce the energy consumption of the building, and the effect of combined factors such as low emission coating layers and phase change materials was investigated in improving the thermal performance of this type of windows and reducing cooling and heating load of the building. The research method was descriptive-analytical with a qualitative study. The data collection tool was a review of written sources, documents, and previous studies, and the method of data analysis was content analysis. The results of the study indicated that using the airflow windows in combination with phase change materials and absorbent or reflective internal curtains with the ability to change the position in the cold and hot seasons of the year, can create a dynamic performance in different seasons, and have a significant effect on reduction of heating and cooling loads and energy consumption in the buildings.

Climate change is one of the most significant environmental reactions that has affected the environment and  along with increasing population, industrial expansion, and urbanization, has led to an increase in urban metabolism and changes in weather patterns. Therefore, thermal comfort, which is a satisfying thermal condition from the surrounding man-made environment, is affected by the surrounding climatic conditions. Historically, the temperature and providing thermal comfort has been one of the most important priority needs of users. In this regard, environmental compatibility, rereading and reproducing concepts in accordance with the environment have been essential. The main objectives of this research in reducing the ambient temperature are to retrieve vernacular strategies and identify the techniques that encompass the natural, cultural, traditional, and social conditions prevailing in an area. The proportions of climatic elements in the façade -the exchange of internal and external boundaries has been one of the main elements in temperature response and balance- including all physical points and vector constituents that form a space with an arch that is closed on three sides, and opened to the courtyard from the front, have shown significant effects on lowering the temperature of their surroundings. In this regard, four porches with four geographical directions (north, south, east and west) in the three houses (with historical antiquity and influential climatic elements like: Sadr Jahromi , Forough–al-Molk and Mohandesi) of Shiraz's historical fabric were selected. In this research, quantitative approaches such as field study and collection of climate data and physical components were used along with computational simulation. The field data and experimental results obtained by devices (portable instruments in the selected buildings) such as thermo-hygrometer to record maximum and minimum ambient temperature and humidity and thermo-pyrometer to measure surface temperature on the targeted points, such as yards and porches were analyzed and validated by Envi-met (climate analysis simulator) software. Lastly, PET thermal comfort index, physiological equivalent temperature and index for determining the comfort temperature in open and semi-open spaces, were calculated using Bio-met software (the impact of all climatic factors can be evaluated by the results of this index). The research results showed that according to the difference between the average PET index of porches and yards, the porch modifier had a greater effect on this index than the yard. Therefore, variables such as the width of the porch, the area of the spatial opening in the facade, and the height of the courtyard have significant impacts according to the geographical direction. By increasing the width of the openings and the height from the surface of the yard, followed by preventing temperature reflections, including long wave infrared radiation emitted based on heat received from surrounding materials and reducing the reception of these rays and their re-emission, the temperature of the PET index decreased, and the PET temperature was in a more appropriate range in terms of thermal perception and degree of physiological pressure. Also, better temperature condition and reduced thermal stress condition were experienced in the porches.

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. 

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).

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.

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.

Over-urbanization negatively affects on urban temperatures and results in the formation of urban heat islands. Outdoor thermal comfort (OTC) occurs in such exacerbated conditions, influencing health, well-being, and productivity of urban dwellers. Therefore, cities need to urgently evaluate the OTC and act to ensure providing acceptable OTC in built-up settings. As such, many studies envisaged to understand outdoor thermal performance of urban environments based on their geometrical features and suggest mitigation strategies against the negative effects of heat stress. Reviewing the literature reveals that most of the previous studies are focused on the urban scenarios of a single canyon or a limited number of individual buildings with simplified and uniform geometrical features without including the effect of surrounding urban neighborhoods. Furthermore, most studies only calculate OTC at a certain time and location in the space where field measurements are conducted. Since these field measurements are scattered in time and space, the comprehensive tempo-spatial distributions of OTC cannot be achieved to have a comprehensive understanding of outdoor environments performance. In this regards, the OTC tempo-spatial visualization is essential in outdoor environments. This study aims to develop a framework to comprehensively evaluate the performance of OTC and assess the effect of geometrical features on the spatial and temporal distribution of thermal comfort in residential neighbourhoods. The proposed framework is applied to the case study of Tehran city where three residential urban configurations are selected with different geometrical features (organic, orthogonal and apartments block) to conduct a series of high-resolution simulations. This study follows a step by step process to understand the impact of built-up urban areas on their thermal comfort performance: (1) development of 3-D models of three selected neighborhoods, (2) tempo-spatial OTC analysis, (3), and understanding the impact of geometrical parameters on the thermal comfort performance. The study reveals that all the selected areas have a significant deviation from the acceptable comfort range with mostly moderate and strong heat stress. The differences in OTC performance of these areas is related to the geometrical features of buildings and canyons including neighborhood layout and proportion of open and built-up areas and canyons’ profiles (building’ height, aspect ratio and orientation). The spatial variation of OTC is more significant in orthogonal areas and apartment complexes while organic settings provide a less distributive comfort performance with lower hours of heat stress and discomfort. Results show that the cooling effect of organic neighborhoods is higher due to the higher rate of aspect ratio in canyons. Orthogonal and apartment cases have higher mean radiant temperature mostly above 40°C. In the apartment complex, open spaces show the highest rate of heat stress, due to the long exposure to shortwave solar radiation. In this area, the most important domain of retrofitting strategies should be focused on landscape planning for green planting and water bodies. The results of this study help to identify design solutions that should be incorporated in the planning studies and as a result, a holistic perspective would be achieved for better decision-making via this tempo-spatial comprehensive analysis.

In the architecture of traditional houses, the environment used to be formed by the mutual interaction of human beings and nature. With the emergence of environmental crises in the contemporary world, the integration of natural and human processes became the most important ecological issue in the domain of sustainability. The aim of the current study is to recognize those ecological criteria of traditional houses which can be productive in the contemporary world so as to arrive at ecological solutions based on the thermal behavior of these houses in cold regions.

These factors are investigated in two traditional houses in Ardabil using descriptive methods, field observations, and quantitative analyses.

The investigation of the most critical climatic condition of the region is indicative of the thermal resistance of the rooms against temperature fluctuations. Furthermore, the analysis of the architectural features taken from physical environment (topography, climate) and structural environment (building form, spatial organization, material, landscape, infrastructure) shows that there is an optimal interaction between these components. The recognition of these architectural features can also provide ecological solutions.

The results of the assessment of the ecological criteria in the houses are also indicative of their conformity with the environment.In fact,these structures have overcome climatic effects via the use of natural resources in a way that rooms like shahneshin and basement which have seasonal function, have optimal performance against temperature fluctuations. For example, in a sample shahneshin room in smaller dimensions, the minimum difference between the inside and outside temperature is 13 °C

This study investigates the effect of facades on the changes in thermal comfort level in open urban spaces. Isfahan city is selected as a case study for warm climate. Brick, travertine, marble, ceramic, aluminum and granite with their own thermal properties were selected as covering materials of the vertical walls of urban valley buildings and data on air temperature, mean radiation temperature, relative humidity and wind velocity were extracted from Envi-met software. Using thermal comfort index of Riemann software, PET is calculated. The results of this study show that the change of the vertical wall-to-granite wall materials in the ratio of 0.5 and East-West facets reduced the air temperature to 1 to 1.1 ° C, 14.1 to 17.9 ° C mean radiation temperature and 8 to 8.3 ° C, respectively. Can be. The same change in materials ratio of 1 reduced the air temperature from 1.38 to 1.49 ° C, 16.45 to 20.92 ° C and 9.23 to 9.63 ° C, respectively. In addition, the use of granite instead of bricks in the aspect ratio of 2 reduces the air temperature to 1.35 to 1.36 ° C, the mean radiation temperature from 28.19 to 30.15 ° C and the PET index from 7.23 to 9.23 ° C. These divergences have also been calculated in the street with a north-south orientation. Finally, using regression method, it can be concluded that among the variables related to the material properties, the material release rate is the most effective material properties on PET index.

A policy to encourage building optimization and to reduce the building’s energy consumption is rating and labeling building’s energy performance which is usually based on the assessment of the building’s thermal performances. The building energy labeling method used in Iran differs from those introduced through international standards. The present paper aims to compare the two above methods. To achieve this objective, the thermal performance of 184 residential buildings are studied in the mild humid climate of Babolsar, using both modeling and “performance approach” methods. The modeling is done using Energy Plus software to predict annual energy requirements. The “performance approach” is methods prescribed by Chapter 19, National Iranian Building Regulations, to compute U-values. All buildings were labeled first based on their annual energy requirements then based on the proportion of building U value to the reference U value. The two ratings show a low correlation (0.2) between them with different labeling in 40% of cases. This renders revisions to the Iranian system inevitable. A combined labeling system is proposed in the conclusion.

Traditionally, among sources of renewable energy, solar energy has played a great role in providing heating and lighting for the building. The heat gain from solar energy, especially in winters, can reduce the need for heating systems and as a result the consumption of energy. However, this issue in summer time can increase space cooling Loads. One of the most important factors for improving energy efficiency in the building is controlling direct solar radiation. Considering that windows are the only part of a building, which allow solar radiation to enter directly, shading is essential to prevent solar radiation penetrating the interior. Shutters are one type of these elements which have been used in Iran's architecture .The wooden type with fixed louvers were common in residential buildings of Tehran in Pahlavi period. Despite the fact that shutters have a great impact on thermal performance, they are not used by contemporary architects in Iran. This research aims to investigate energy efficiency of window shutters with different parameters: installation place, control method and material. The results show that the external shutters with movable louvers and intelligent control have greater effect on reducing thermal loads compared to the other types.

Now a day, climate change and environmental crisis as a global threats have negative effects on all living creatures. These phenomena have been happened because of consumption of non-renewable energy sources such as oil, gas, and coal since the last century. Due to recent obligations to preserve these sources and environment, it is necessary to reduce the consumption of these sources. The residential sector energy consumption accounts for 31% of the energy globally used. This fact, hence, makes it inevitable to further study the thermal performance of residential buildings. Therefore, adjusting the climate of the building surroundings would affect buildings thermal performance. Creating the apt micro-climate around buildings will contribute to the improvement of the building thermal performance. In Iran’s traditional buildings, the central courtyard has always been one of the most effective climate solutions to decrease the temperature in hot- arid regions. Along with an increase in shading by trees and building walls, the building would be protected from direct sunshine and thus, thermal conditions on hot days would balance. It is noteworthy that this shading should not block the sun in cold seasons. In this regard, the aim of the present study is to make alterations in locating the building on the land, so that to create three and four-sided courtyards in urban blocks. Therefore, we could benefit the micro-climate performance in order to decrease energy consumption in these buildings. There has been widespread research about this in different cities of Iran. Despite the necessity to cut down the energy consumption of the residential sector in a metropolis like Tehran, few of these studies have been conducted in this city. Consequently, the case studies of the current research, are residential blocks of apartments in Tehran. Due to different climates in Tehran, central and southern areas were chosen as thesis climate background, because these areas are classified as hot- arid regions. The research method consists of simulation, empirical methods, and logical reasoning. In the beginning, Tehran 7th urban zone was chosen with GIS assistance and calculations were done. Then, thermal performance of the proposed models and the effect of the courtyard on sun energy absorption, access to daylight and wind, were studied by using DesignBuilder software. The results were then compared to the reference model. The results show that four-sided courtyard in Tehran would significantly decrease building cooling load in summer which is about 18.35 kWh/m2. In winter, however, significant impact on the heat load is absent. Field measurements in Memar Bashi Seminary in Tehran, also showed that the temperature in the courtyard is considerably less than that of the outside area. This difference would reach 5 degrees centigrade at the hottest hours. The temperature inside the building is also 1 to 2 degrees centigrade less than that of the courtyard. On the other hand, the graphs obtained from simulations and field measurements also presented a similar pattern. Thus, the results of filed measurements confirmed simulations performed in DesignBuilder software.