چكيده لاتين :
Introduction
Sustainable development, the state of balance and equilibrium among the various dimensions of development, in three principles of environmental sustainability, economic sustainability and social sustainability is one of the fundamental goals of seeking to strengthen the dimensions of environmental considerations in particular. Energy sustainability can be explored within the framework of sustainable development. Therefore, the goal of sustainable energy programs is to generate and consume energy resources in a sustainable logical way, so that human life and ecological balance could be possible in the long run. According to available statistics, about one third of global greenhouse gas emissions and 40% of global energy consumption are related to the construction sector, which leads to significant economic, environmental and social consequences. Understanding energy consumption in the building sector is important in order to achieve new goals and approaches such as sustainable urban development, new urbanism, energy efficient city and reducing environmental pollutants. In this regard, the external walls of residential building as an effective factor emphasized by the national building regulations (19th volume) and numerous studies on the transmission or loss of thermal energy have an effective role in the energy consumption pattern of residential buildings according to operational cycle. On the other hand, because of the importance of calculating the embodied energy of the external walls of residential buildings and the lack of comprehensive research in this field, a study to assess these indicators in line with the objectives of sustainable environmental development in terms of energy efficiency and reduction of pollutants in the environment is needed. Therefore, the present study aimed at assessing the embodied energy of the production period and the operational cycle as well as the CO2eq of 60 years of building life, with an emphasis on the common external walls of residential buildings in Sanandaj. An analytical approach in this regard seems to provide a broader vision for decision makers in the field of construction as well as large-scale metropolitan managers.
Methodology
According to the analyses from previous studies, researches generally focuses on one of the energy consumption building periods, and sometimes they generally outline the results with no tangible methodology on a large scale, without taking into account any of the effective building elements in energy consumption. Considering the major share of energy consumption in Iran by residential buildings, the proposed evaluation method of this study aims to identify and make a comparison of the external walls of urban housing using a life-cycle method in order to assess the embodied energy and environmental pollutants in the production period as well as energy consumption during the operational cycle. According to the analytical-descriptive approach, after explaining the related principles, Delphi method and Fuzzy AHP hierarchical analysis were used to identify and zonate the frequency of common external walls of housing in the three- areas of Sanandaj city.
Then, the consumption of embodied energy in the production period was assessed with the existing data and the energy of the operational cycle, using modeling and simulation of a city block in Design Builder software considering the relevant variables. Interpretation of the findings was done using SPSS software, ANOVA statistical analysis, and Duncan's test for comparing the classifications of the embodied energy levels in the production and operational cycle among the walls and its extent in the three regions of Sanandaj.
Results and Discussion
According to the results of the survey, all types of walls were classified in 10 main types and 36 sub-categories. The 20 cm compressive bricks and hollow clay blocks of 15 cm were used the most in the walls of Sanandaj city in zone 1. In the 2nd and 3rd areas, in addition to these two types of walls, the 20cm hollow clay block was also considered as the third priority in the frequency of the walls, as well as the use of new materials with low thermal conductivity with a low percentage such as the block of LECA and Hebelex were obvious in these two areas. The final results of the estimation of the embodied energy and Co2eq for each square meter of the external walls of residential buildings, and the results of the analysis of the primary embodied energy in the levels of different types of walls were significant. The lowest amount of primary energy belonged to the type 5 wall (permeable clay block of 15 cm) and the highest primary energy belonged to the type 2 wall (20 cm pressure brick) which were 441.5 and 1066.5, respectively. Also, the lowest level of CO2eq belonged to the type 10 wall (the 15-centimeter HEXAC block) with the middle layer of expanded polystyrene and the highest level of CO2eq belonged to the type 2 wall (20 cm pressure bricks), were 7.773 CO2 / kg and 24.761 kg CO2 / kg, respectively. Also, urban area 1 has the highest embodied energy consumption and Co2eq and urban area 3 had the lowest embodied energy consumption and Co2eq for each square meter of external walls, which was due to the high contribution of the type 2 wall (20 cm pressure bricks) in urban areas 1 (46.21%) and its smaller share in urban area 2 and 3 (27.26%). Final results of the energy of the operational cycle for each square meter of the common external walls of residential buildings, the lowest amount of energy consumed during the operational cycle belonged to the type 9 wall (Hebelex block of 10 cm with the middle layer of polystyrene), which was 2778 kWh per square meter. Also, the highest amount of energy used for the type 1 wall (10 cm non-exterior bricks) was estimated to be 903.93 kWh / m2. According to the above results, the share and percentage of embodied energy used in the residential buildings in the three urban areas were 3.35%, 3.13% and 3.10%, respectively. Therefore, according to the above percentages, it can be concluded that the amount of embodied energy consumed compared to the total energy consumed in the building, if counted by the year, in the three urban areas is equal to 1.01, 1.87 and 1.86 years, respectively from the 60 years the approximate life of the building.
Conclusion
Leading countries have made significant efforts to reduce these pollutants and optimize energy use. In Iran, valuable measures have been taken in the area of pollutants and thus, optimization of energy consumption during the operational cycle has been carried out within the framework of the 19th issue of the building. These measures should be promoted at a widespread and high quality oversight in urban areas, taking into account the lifecycle of the building. The present study presents a methodology for estimating the life cycle of the building, considering the embodied energy and operational cycle, a meaningful relationship between energy consumption levels and hence Co2eq contaminants in relation to the external walls of the residential building were estimated in the three areas of Sanandaj. By comparing the embodied energy consumption of the production period and operational cycle, the unfavorable condition of the use of inappropriate walls is shown to be the most important and most effective factor in energy consumption. The results, while confirming the field studies of the energy assessment sector, of the production and operational cycle of the current research in terms of estimated values, it is suggested to be compared to the current situation in the decision-making of urban management in order to improve the status quo in the form of regulations and guidelines. The executives, as well as the designers and experts in the field of construction, should consider the above results in the city of Sanandaj, and take measures for the external walls of residential buildings.
