Showing 64 results for Energy Consumption
Volume 0, Issue 1 (5-2011)
Abstract
A numerical model for two-phase debris flows is developed in this paper, on the basis of understanding of the physical characteristics of debris flows from field investigations and experiments. Employing a moving coordinate, the kinetic energy equation of gravel particles in unit volume in debris flow is developed by considering the potential energy of the particles, energy from the liquid phase, energy consumption due to inner friction-collision between the particles, energy dispersion through collisions between particles, energy for inertia force, energy consumption due to the friction with the rough bed and energy consumption at the debris front. The model is compared with measured results of two-phase debris flow experiments and the calculated velocity profiles agree well with the measured profiles. The gravel’s velocity at the debris flow head is much smaller than that of particles in the following part and the velocity profile at the front of the debris flow wave is almost linear, but the profile in the main flow shows an inverse ‘s’ shape. This is because the gravel particles in the main flow accelerate as they receive energy from the gravitational energy and flowing liquid and decelerate as they transmit the energy to the debris flow head and consume energy due to collision with the channel bed.
Volume 2, Issue 2 (10-2012)
Abstract
In the last decade, there has been more attention towards the assessment and improvement of construction phase embodied energy. In addition to buildings maintenance energy, large amounts of energies are consumed in construction process which is called embodied energy. This research results from recording all types of energies used in construction phase and presenting a numerical calculation method to assess the embodied energy of area unit and also decreasing this energy to its lowest possible limit. In order to achieve the minimum embodied energy, three energy consuming phases are calculated for 1400 square meter case study; which are material embodied energy, transportation energy and erection and on-site energy. Deviation of total embodied energy for the area shows 795.14 GJ/M2 as embodied energy. This digit is a reliable benchmark for comparing these three energy consuming phases and also comparing this construction system with other ones. Total embodied energy it the result of all three parts. But analysis of them shows that it's necessary to substitute some materials with more optimized ones. The result of this substitution decreased the embodied energy to 12.75 GJ/M2 and which is about 1.6% of the first measured embodied energy.
Volume 4, Issue 2 (9-2014)
Abstract
The building sector is responsible for one-third of global final energy consumption and thus environmental damage, carbon dioxide production. Some reasons for ever increasing building energy consumption : climate change, increase in household electricity load , the growth of real estate, fast-growing household electrical appliances, changes in industrial structure, huge energy consumption of the existing buildings, and the lack of strict government supervision. The world's total energy requirements are mostly used in sectors such as transportation, industry, residence, commerce, etc.. Although most of the energy consumption during the period 1973 to 2009 belonged to the industrial sector, it can be said that the proportion of residential buildings is very high and is increasing rapidly.. World Statistics published by the Department of Energy, United States of America in March 2010 shows that most houses widely use energy for heating and hot water and then cooling and lighting. Therefore, the revision of quality architectural design of buildings, based on the climatic principles , will be very effective in optimizing fuel consumption so that the energy consumption can be controlled wisely and optimally. On the other hand the use of renewable energy technologies can provide energy surplus of buildings and eliminate the problems associated with fossil energy in great extent.Adopting conservation measures on a large scale does allow reducing both electricity and total energy demand from present day levels while the building stock keeps growing. They simulate climate-dependent hourly building energy demands at user-defined scales, typically an individual state or utility zone. Due to the effective role of energy in economic development and its increasing consumption in parallel with the growth of human communities , considering resource constraints and preventing from facing with an energy crisis, the need for conservation through management application is necessary which demands new strategies and approaches in both environmental and architectural revisions for design and building. In particular, the high energy consumption especially in buildings is a major problem in developing countries which has economic and environmental impacts of prime importance while it is considered to be the most significant cornerstone of growth in different dimensions. Buildings , it is statistically shown, account for a third of total global energy consumption. Energy consumption in buildings is increasing due to several factors including climate change, increasing electrical energy consumption in households, real estate development, diversity of modern appliances, changes in industry structure, very high energy consumption in existing buildings and the lack of adequate supervision of the state.. Therefore, efforts must be focused on the control and management of energy consumption . The purpose of energy management is reducing energy consumption in a way that is logical and economical and can cause no negative effects on welfare and thermal comfort. So, a focus for building energy consumption efforts is of great importance. The occupant behavior and building manner can both increase the building energy consumption, especially residential ones.In the building quality part, there are many techniques affects on building energy consumption, which divide to passive and active. The passive ones are the techniques that related to the body and design of a building as material, utilization of solar radiation on the bodies, length and width of building, insulation, window, and so on without electrical or other energy portfolio, but the effect of these parameters was not equal. Therefore, this study presents an approach to determine the effect of main parameters of some of the building techniques on energy consumption. In this study, these parameters were identified and evaluated and finally were Prioritized. Not all of the parameters has equal role on energy consumption, which the mentioned weights indicated. The remainder of the paper organized as follows. Firstly, the parameters were identified by research and interview. The effective parameters recognized as the alternatives of the mentioned hierarchy3 step trees, which can be listed as follows: occupants; built area; Step No.; Proximity degree; Window to wall ratio; Length to width ratio; Side. Secondary, the questionnaire performed and completed by experts as architects, mechanical engineers and energy engineers. Analytic hierarchy process (AHP) and its applications in surveys related to buildings were presented. Up to now, the AHP method has been widely applied in the general policymaking in buildings. Next, the effective parameters on energy consumption evaluated, and in next section the AHP for the approach concernedexplained and resultsoffered. Finally, the last Section includes the concluding remarks. The weights and priorities of the effective parameter are illustrated. As a result, considering weight of factors in building designing process, the different parameters of BO can be classified and evaluated: First, the main effective parameter is window to wall ratio. Depends on the weight of this parameter (0.36), the window area and materials are important for building designers. Another main parameter is side no., if a building has 1 or 2 or 3 or 4 side, its energy consumption differs fundamentally. Choosing the main direction, side and the side no. are all associated. One of the main results is about the building area depending on energy consumption, which considers having the main role, but in present survey concluded that the third effective parameter is area. The least effective parameter is occupant number, due to energy load of building space and quality, not building occupant. Urban designers and Architects considering Building Orientation (BO) and its parameters can design buildings that are energy efficient. If building orientation )BO( is considered, solar radiation absorbed by the surface structure of the building will become more favorable, and consequently the energy consumption will be reduced. However, if the building orientation (BO) is considered along with climatic factors, there will be direct effect of increased energy costs. In addition , urban designers must greatly pay attention to building sides while determining the building blocks as the transmitting surfaces are from outdoor to indoor in summer and vice versa in winter. Architects must also pay attention to different ratios of windows to create the proper ratio of heat transfer in the buildings. The materials used in the buildings are of great importance.
Volume 5, Issue 4 (2-2016)
Abstract
Volume 6, Issue 4 (2-2017)
Abstract
Volume 6, Issue 4 (2-2017)
Abstract
Volume 7, Issue 1 (11-2008)
Abstract
Internal thermal conditions and cooling load of the buildings intensely depend on outdoor conditions. Outdoor conditions of the building are not constant during a day, so assumption of constant thermal conditions for indoor is not proper. It seems that using adaptive temperature panels proportional to the variations of outdoor conditions decreases the energy consumption in comparison with constant temperature cooling panels. In this paper the effects of adaptive temperature metal panels are investigated on energy consumption of the buildings and thermal comfort conditions of the occupants. Results of hourly analysis show that, in Tehran with maximum relative humidity of 65%, in buildings with north and south orientations, we do not need cooling systems in nearly 10 hours of a day, in remains we can provide thermal comfort conditions by radiant ceiling cooling panels with natural ventilation and without any anxiety about condensation on the panels. However, in buildings with east or west orientations we do not need to air conditioning and cooling systems in only 7 hours of a day. In these buildings condensation is inevitable in some intervals of system operation during a day. In these periods, we can decrease the probability of condensation by using mechanical ventilation. Results also demonstrate that cooling energy consumption is decreased of 29 to 45% depending on the orientation of building.
Volume 7, Issue 26 (10-2010)
Abstract
A laboratory dryer used for a thin layer of 165 g Thompson orange slices with three thickness levels of 2, 4 and 6 mm, five different temperatures of 40, 50, 60, 70 and 80 °C and three air speed levels of 0.5, 1 and 2 m/s were employed to find the best dried and minimum energy consumption. This experiment was done in a complete randomized block design with the factorial treatments performed in three replicates. The energy consumption for drying thin slices of orange was calculated accordingly. The analysis of results showed that the lowest and highest drying energy consumption were 3.35 kWh (for 2 mm slice thickness and 40 °C) and 15.2 kWh (for 6 mm slice thickness and 70 °C), respectively.
Volume 8, Issue 1 (10-2008)
Abstract
Internal thermal conditions and cooling load of the buildings intensely depend on outdoor conditions. Outdoor conditions of the building are not constant during a day, so assumption of constant thermal conditions for indoor is not proper. It seems that using adaptive temperature panels proportional to the variations of outdoor conditions decreases the energy consumption in comparison with constant temperature cooling panels. In this paper the effects of adaptive temperature metal panels are investigated on energy consumption of the buildings and thermal comfort conditions of the occupants. Results of hourly analysis show that, in Tehran with maximum relative humidity of 65%, in buildings with north and south orientations, we do not need cooling systems in nearly 10 hours of a day, in remains we can provide thermal comfort conditions by radiant ceiling cooling panels with natural ventilation and without any anxiety about condensation on the panels. However, in buildings with east or west orientations we do not need to air conditioning and cooling systems in only 7 hours of a day. In these buildings condensation is inevitable in some intervals of system operation during a day. In these periods, we can decrease the probability of condensation by using mechanical ventilation. Results also demonstrate that cooling energy consumption is decreased of 29 to 45% depending on the orientation of building.
Volume 8, Issue 1 (6-2018)
Abstract
Aims Indoor air quality (IAQ) is one of the factors that determines the performance and maintenance of the building and affects the health and well-being of building users. The present study aimed at evaluating the breathing wall modeling to absorb indoor pollutants in the living room of a house inspired by the buffer zones of traditional architecture in hot and arid climate of Iran.
Materials & Methods The present descriptive study was carried out, using library method and computer modeling inspired by traditional Iranian architecture and sub-climate design of indoor climate and, as a result, the combination of pollutant adsorbent plants design in architectural space. Through ANSYS FLUENT 6.3.26 software, the effect of contaminated fluid release in the room space, as well as the concentration of the matter and its release were investigated by the snake plant with the boundary conditions. The air inlet was considered fixed at a speed of 0.5m/s, the output was considered relative constant pressure at zero atmospheres, and the walls were considered fixed with non-slip condition.
Findings The wind situation in the room was useful for diluting pollutants. The process of reducing the concentrations of pollutants was Suitable for the time, adequate, and appropriate by using plants.
Conclusion Based on wind condition modeling and the combination of pollutant adsorbent plants design in architectural space, plants contribute to dilution of pollutants, air conditioning, and deposition of suspended particles through the production of oxygen during photosynthesis and also the absorption of pollutants from the environment.
Volume 8, Issue 3 (12-2018)
Abstract
During the energy crisis and the world’s attention to optimal energy consumption, especially in buildings, the walls of the buildings became one of the most important parts of the design process. In the first step, air locking and isolation of the walls were important in order to prevent the loss of energy. In the next steps, the need to get proper solar radiation in cold areas and the existence of a tool to prevent the entry of solar radiation in hot areas was raised. The aim of this paper is to investigate the effect of the shading tool location and the optimal combination of glass layers in double skin facade in the warm and humid climate of Iran. The methodology for achieving this goal is to use computer simulations (Fluent software). In this study, different configurations of double skin facade have been investigated. During these surveys, the structure has been considered optimally in the Kish Climate Zone. Three different areas were investigated for the establishment of shaders; the findings of this study are presented as temperature and air flow diagrams and contours. The results of this research show that the most suitable place for the establishment of the shadow tool is the interior and back of the double skin façade. It was also found that the proper type of double skin facade, in order to prevent the optimum from increasing the internal temperature, includes a glass layer in the outer shell and a window with a double-glazed glass in the inner shell. In this paper, the “simulation and modeling research” method has been used. In this paper, the “simulation and modeling research” method has been used. In the software simulation and numerical analysis sections, the type of quantitative research is “analytic” research method and results are obtained based on “induction”.
Volume 8, Issue 3 (12-2018)
Abstract
This study has scrutinized the methods of optimizing the energy consumption in Isfahan dwelling, and how to provide the residents with comfort, well-being and satisfaction through green architecture. Given the excessive consumption of energy in Iran and also Hot and Arid climate of Isfahan, this essay has aimed at preservation of energy resources for future generations and boosting the quality of life for the dwellers by means of green architecture. This article, by revealing the notion of comfort, has confirmed that the ecological architecture would minimize the required energy through maximum use of natural desired conditions alongside protecting buildings from unfavorable climatic factors and would provide a part of energy within the natural way. As a result, comfort would be offered in the areas, in a more pleasant way. With the green architecture approach, studies on the historical houses in Isfahan indicate the desirability of life quality in these buildings through improving comfort by means of optimizing energy use. Nowadays, the urgency of developing sustainable behavior, including the management of energy resources, is evident. Considering the prominence of the users’ behaviors in achieving sustainable architecture goals, this paper, by putting basis to Maslow pyramid, has suggested two strategies, “training” and “resource management”, so as to promote sustainable behaviors. This research has been based on applied research methods, citing library studies and electronic resources. In the end, it has argued about how to select eco-friendly materials and has proposed utilizing recycled materials and reusing of waste in favor of green design.
Volume 9, Issue 1 (12-2009)
Abstract
In cold season, draught or undesired local cooling sensation in ankle and neck region is one of the most frequent cases of complaint of the occupants. A person who are subjected to draughts in winter, tend to elevate the room temperature to counteract the cooling sensation, thereby increasing the energy consumption. In naturally ventilated buildings, draught is due to windows and other cold surfaces in the room. Draught is dependent on the air speed and on the magnitude of turbulence intensity. Serious draught complaints can often occur at mean speeds lower than those recommended by standards when turbulence intensity is high. So investigation of undesired local cooling in floor heating systems is very important, although in these systems the mean air speed is not significant. In this paper, the effects of size of window on draught are investigated in floor heating systems. Results demonstrated that, undesired thermal discomfort caused by local cooling phenomenon in floor heating systems is negligible. At the end, the probability of occurrence of local cooling phenomenon in floor heating systems is compared to vertical heating panels. Thereby the floor heating systems are more effective than the vertical heating panels in aspect of thermal comfort and energy consumption.
Volume 9, Issue 1 (12-2009)
Abstract
In cold season, draught or undesired local cooling sensation in ankle and neck region is one of the most frequent cases of complaint of the occupants. A person who are subjected to draughts in winter, tend to elevate the room temperature to counteract the cooling sensation, thereby increasing the energy consumption. In naturally ventilated buildings, draught is due to windows and other cold surfaces in the room. Draught is dependent on the air speed and on the magnitude of turbulence intensity. Serious draught complaints can often occur at mean speeds lower than those recommended by standards when turbulence intensity is high. So investigation of undesired local cooling in floor heating systems is very important, although in these systems the mean air speed is not significant. In this paper, the effects of size of window on draught are investigated in floor heating systems. Results demonstrated that, undesired thermal discomfort caused by local cooling phenomenon in floor heating systems is negligible. At the end, the probability of occurrence of local cooling phenomenon in floor heating systems is compared to vertical heating panels. Thereby the floor heating systems are more effective than the vertical heating panels in aspect of thermal comfort and energy consumption.
Volume 9, Issue 2 (9-2019)
Abstract
Aims: Optimizing energy consumption in buildings, which includes a large part of the total energy consumed in the country, is very important. The window is also part of the interface inside and outside the building. The purpose of this research is to optimize the opening in the office in Tehran in terms of obtaining enough daylight and reducing energy consumption.
Methods: Simulation and optimization of the window performed parametrically in the Grasshopper and analysis of the objectives using the Honeybee and Ladybug plugins. The spatial Daylight Autonomy (sDA) and the Energy Use Intensity (EUI) calculated for proportions and varied window positions in eight variable directions.
Findings: The windows on the eastern north rotation and later in the east rotation had the best results. The window to wall ratio was 20% to 28%, with an average length of 6.53 and 0.9 meters, respectively, for the research model, the most ideal response. The distance between the windows to wal and the sillheight were respectively 0.65 and 2.22 meters.
Conclusion: Using modern simulation techniques enables building designers to have more intelligent choices in design with scientific approaches. The repeatable framework presented in this study can be used for buildings with different user positions or proportions, and ultimately enable designers to play an effective role in sustainable development by increasing their design productivity.
Davood Behbudi, Hossien Asgharpour, ,
Volume 9, Issue 3 (10-2009)
Abstract
Understanding the different aspects of the relationship between energy consumption and economic growth can outstandingly help to adopt appropriate policies in energy sector. Structural breaks and regime shifts may affect the above relationship. Therefore, it is important to consider structural breaks and regime shifts in empirical analysis.
In this paper, the relationship between energy consumption and economic growth is analyzed in the presence of structural breaks. The empirical models are specified and estimated using Iran's time series data during 1967- 2005 period. To this end, unit root tests proposed by Zivot and Andrews (1992) are first used to identify structural breaks found endogenously and then the Gregory-Hansen cointegration test, which allows strctural breaks in time series, is employed to estimate the long-run relationship between energy consumption and economic growth. The results show that in the long run, there is a positive and significant relationship between energy consumption and economic growth in Iran.
Volume 10, Issue 2 (9-2020)
Abstract
Aims: After the attention of the global associations to optimal using of energy, exterior walls of the buildings became one of the most important parts of the designing process. The present study aims to investigate the effect of airflow type and also the optimum spacing between two walls in this façade in the warm and humid climate of Iran (Kish Island).
Methods: In order to achieve this goal, various configurations of double-skin facades have been investigated using computer simulations (Fluent software 19.2). Two types of air evacuation of airflow and external air layer were investigated. Each of these two flows was simulated with three different distances of 1000, 1500, and 2000mm. In the present study, “the
simulation and modeling research method” has been used. In the software simulation and numerical analysis sections, the type of research is “quantitative” and the research method is “analytical”, and the results are obtained based on “induction”.
Findings: The results show that during the peak periods of heat and humidity, when the outside air is not in a comfort state, the type of air evacuation causes high temperature and humidity inside the offices, and
makes trouble for the thermal comfort of the residents and users.
Conclusion: In warm days and months, it is necessary to use an external air layer. It was also found that in the case of using air evacuation, the optimum depth of air cavity is 2000mm and in the case of external air, curtain layer is 1000mm.
Zahra Nasrollahi, Marzieh Ghaffari Gulak,
Volume 10, Issue 3 (10-2010)
Abstract
Economic development is one of the major policies of a country which is concerned to industry and technology on one hand and leads to environmental pollution on the other hand. The experiences of developed countries show that economic development with emphasis on the industry sector, without any attention to environment, can create serious problem against sustainable development. Industrialization has caused increasing energy consumption and therefore air pollution. It's so important to consider the relationship between industrial activities and industrial pollution in developing countries, because industry sector has a basic role in development process of these countries.
Therefore the aim of this study is examining and qualifying of linkage between industrial activity and air pollution, using an industry-level dataset of IRAN manufacturing industries during the period 1995-2007. The result of study shows that air pollution is a positive function of energy consumption, industrial activity and physical capital intensity and also is a negative function of labor productivity, fuel price and human skill intensity.
Volume 11, Issue 1 (6-2011)
Abstract
The window is an external envelope of the building that has more effect on the building energy consumption and human thermal comfort. So, calculating of window heat transfer is an important task. Since, calculating of the window energy transfer is difficult and must be calculated with the computer simulation, simple equations are necessary to estimate the window energy transfer and to compare the different window types. In this study, using computer simulation, a new equation has been presented to calculate double pane glazing window energy transfer. Using this equation, the window parameters can be designed based on the minimum window energy transfer. Also to compare the different window types (with or without overhang) a coefficient as "Efficiency Coefficient" has been defined. The result show that the window energy transfer decreases with the Efficiency Coefficient decreasing. Therefore, this coefficient can be used as a criterion to select the optimum window based on yearly minimum energy consumption.
Volume 11, Issue 2 (9-2011)
Abstract
Abstract- The correct selection of typical meteorological year is an important factor for accurate building energy simulation. In this study, the Sandia method has been applied to analyze the measured weather data of a 14-year period (1992–2005) in Tehran and to select the proper data for the typical meteorological year. Also, typical meteorological year has been generated by using the Meteonorm and Weathergenrator softwares. Then the results of the Sandia method and the two mentioned softwares have been compared with long term average measured data for main parameters in the weather data file. It was found that, the results of the Sandia method has good agreement with the long term average measured data but the created TMY data by the Weathergenrator and Meteonorm softwares have not good agreement with the long term average measured data.
