Among all energy-saving methods, building energy-saving is of great significance. In building construction, the wall plays a major role in maintaining the structure of the building, so in order to control the energy consumption of the building, it is necessary to save energy on the wall and do a good job in building insulation.
At present, China's environmental pollution is serious and resources are exhausted. We must fully implement the concept of low-carbon and green in construction projects, take environmental protection and ecology as the principles in the application of building materials, increase the application of building insulation materials, and realize the effective combination of economic benefits and environmental benefits. In this paper, the evaluation model of life cycle and environmental economic benefits of building insulation materials is established, hoping to bring reference to the sustainable development of construction industry.
Key words: building thermal insulation materials; Life cycle; Economic benefits; Environmental benefits; evaluate
First, the development of building energy efficiency assessment
In the past, the thermal analysis of a single building mainly focused on the energy consumption during the operation of the building. At present, computer aided design (CAD) has made good progress and is widely used in the study of building energy consumption. Now, a building thermal environment analysis software DeST is born on the basis of CAD, which can simulate and calculate the annual energy consumption and room temperature of buildings under certain parameters. However, there is little research on it and LCA, so it is difficult to give full play to its comprehensive advantages in both comments and management. At present, people attach great importance to the energy-saving effect, selection and thickness of thermal insulation materials, mainly because the selection of thermal insulation materials is related to energy saving and environmental pollution caused by garbage generated in the later period of construction, so it is necessary to analyze the ecological damage level and resource energy consumption of thermal insulation materials, and it is very necessary to select and analyze thermal insulation materials for building exterior walls according to the targeted application life cycle principle in different regions.
Second, DeST energy-saving model simulation calculation
DeST-h is a software platform for HVAC system and building environment simulation. It is widely used in the calculation and analysis of influencing factors of building thermal characteristics, thermal characteristics indexes, room temperature, annual dynamic load of building and the economy of terminal equipment system. The software can not only ensure the accurate results of the annual cumulative cooling and heating load, but also be at the leading level in the world in hourly dynamic room temperature simulation. The first is the building model, which is established according to the height, orientation, quantity and size of the room and the total size of the external structure. The second is thermal parameter design, which determines outdoor meteorological parameters according to the thermal partition of the building and the location of the model. These data are simulated and calculated by random algorithm, involving indoor thermal environment design indicators (bedroom design temperature and air exchange times in winter and summer) and external climate parameter information (heating and air-conditioning days, dry-bulb temperature of air-conditioned heating room in winter and summer).
In addition, it is necessary to simulate the heat transfer coefficient and window-wall ratio of external windows with different orientations, calculate the date of heating and air conditioning season, and determine the heat consumption according to relevant standards, so as to calculate the proportion of external wall insulation area to the total construction area and heat transfer coefficient according to DeST software. The third is thermal simulation and benefit calculation.
The load statistics of air conditioning and heating in energy-saving mode without external wall insulation and reference mode are carried out, and the total energy-saving value of the whole year is determined by comparison. If the annual energy saving is converted into electricity price and corresponding coal consumption, and the reduction of pollutants such as carbon dioxide, sulfur dioxide, nitrogen oxides, carbon dust and soot is calculated, then the emissions of these pollutants are expressed by numerical values. So as to obtain energy benefits and economic benefits. The investment cost life cycle of several common insulation materials is given, such as 50-day recovery cycle (as shown in table 1). On the basis of considering the production cost, the production cost, payback period of investment funds and expected environmental benefits of polyurethane, rock wool, XPS and EPS were compared.
Third, the life cycle model of external wall insulation materials
The following formula is applied to the total energy consumption during the life cycle of a building. That is, the total amount of e =E birth +E application +E residence +E demolition +E waste. These six factors are expressed as the total energy consumption of building life cycle, building materials production stage, building construction stage, residential use stage, demolition stage and waste building materials disposal stage. Because reinforced concrete and other materials are irreplaceable, only thermal insulation materials are considered, which is simplified into three stages: production, transportation and operation of thermal insulation materials. The total cost per unit area of external wall only considers these three aspects, namely, the production cost of thermal insulation materials, the transportation cost of materials and the heating and air conditioning cost.
As far as the production stage is concerned, its energy consumption includes the direct energy consumption of thermal insulation materials, the energy consumption of mining, transportation and production of superior materials, and the primary energy consumption required for production. It is related to the rejection rate, thickness, density and energy consumption of unit building materials in the manufacturing process. As far as the transportation stage is concerned, it is related to the allowable consumption during replacement and the distance between the supplier and the construction site. It also involves several concepts, such as energy consumption of thermal insulation materials in transportation unit, the distance from waste generated by thermal insulation materials transportation to construction waste landfill, the average distance of thermal insulation materials from suppliers to construction site, the thickness of thermal insulation materials, the density of thermal insulation materials, and the rejection rate of thermal insulation materials in manufacturing process.
As far as the operation stage is concerned, its heating and cooling energy consumption includes heating and cooling energy consumption, and the number of heating days and air conditioning days has different values in different regions. The energy consumption of heating and cooling in operation stage is related to the operation efficiency of heating system, the thermal resistance of external wall except insulation layer and the service life of insulation materials. The service life and energy consumption of concentrated materials such as polyurethane, rock wool, XPS and EPS are considered in the calculation, and the total energy consumption of these materials is calculated. The order of total energy consumption in the whole life cycle can be judged, and the order from big to small is polyurethane, RPS, XPS and rock wool. The order of energy consumption in each stage is operation, production and transportation. The energy consumption recovery period of the four substances is polyurethane, XPS, EPS and rock wool in turn.
Fourth, the scientific evaluation and policy development direction of external wall thermal insulation materials
The scientific evaluation of building thermal insulation materials is complex and has research significance. Life building materials refer to recyclable building materials that do not affect the ecological environment and consume little energy and resources in the whole process of development, production and use. On the basis of building life cycle assessment, foreign scholars combine economic benefit analysis with environmental benefit analysis, forming a modern sustainable LCA analysis different from the traditional model. Its evaluation content includes social, economic and environmental aspects. In the social aspect, it mainly includes the income of workers, the rate of physical examination of workers, the social welfare of workers, the employment rate of women, the accident rate and so on. As far as economy is concerned, there are mainly manufacturing costs, power costs, fuel costs, raw material costs, garbage disposal costs and so on.
As far as the environment is concerned, there are global warming, human toxicity, eutrophication, ozone depletion, ecological toxicity and so on. Although China tries to popularize this evaluation method, due to its high cost, long development time and clear requirements from users, most users are uncertain about their own needs, and their enthusiasm for overall participation and investigation is not high. At present, China has higher requirements for the combustion performance of organic thermal insulation materials, and there must be halogen-free flame retardants in thermal insulation materials. The flame retardant system of this new thermal insulation material includes, for example, a flame retardant which is a combination of metal hydroxide and phosphorus, which not only produces a small amount of smoke, but also does not produce toxic and harmful gases when burning. The comprehensive evaluation and other technical indexes of thermal insulation materials have changed after combustion, which also affects the evaluation and selection of thermal insulation materials to some extent.
Verb (abbreviation of verb) conclusion
Building thermal insulation materials can effectively understand the environmental and economic benefits of each material by establishing DeST simulation energy-saving simulation model and life cycle model. Through comprehensive comparison, the materials with the strongest comprehensive benefits are adopted. In the life cycle of thermal insulation materials, it involves production, transportation, operation and other processes, as well as production, construction, owners and other subjects. Comprehensive consideration of these processes and subjects ensures the optimization of the whole life cycle of building insulation materials.
refer to
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Jun Xiao, Zhao Ping, Rui Liu. Study on life cycle environmental impact of building insulation board [J]. Journal of Safety and Environment, 20 13, (01):138-141.
[3] Feng Haoru, Peng Ying. Economic evaluation method of external thermal insulation and energy-saving system based on life cycle principle [J]. Sichuan Building Science Research, 201,(02): 277-279+286.
Hu, Su Zhenguo,. Research and application of external thermal insulation materials for building external walls [J]. Material Guide, 20 12, S2:290-294.
Further reading: What is a graduation thesis?
Graduation thesis is an article with certain academic value submitted by college graduates. It is a landmark assignment for college students to complete their studies, a comprehensive summary and review of their learning achievements, a preliminary attempt for college students to engage in scientific research, a written record of their own scientific research achievements under the guidance of teachers, and a comprehensive answer sheet to test students' basic ability to master knowledge, analyze problems and solve problems.
Stylistically, graduation thesis belongs to the category of academic papers in argumentative essays. The so-called argumentative essay is an article that proves the correctness of Bai's point of view. It includes all articles that prove things, including political theory, literary theory, miscellaneous theory, or arguing, commenting, refuting, or thinning evidence, so as to distinguish right from wrong, dispel doubts and doubts, synthesize Dayi Chen, refute fallacies and so on. As far as the content of graduation thesis is concerned, one is to solve a problem in the discipline and answer it with one's own research results; One is to put forward only a certain problem in the discipline, synthesize the existing conclusions of others and point out the direction of further discussion; There is also a kind of partial answer to a question in the proposed discipline with one's own research results. The graduation thesis focuses on the reasonable division of objective things, points out their essence, and puts forward personal academic opinions and methods and opinions to solve a certain problem. As far as its form is concerned, graduation thesis has the general attributes of argumentative essay, that is, argument, argument and argumentation are the three major elements of the article. This paper focuses on logical thinking, emphasizes the fact-based, shows the rigorous reasoning process and draws convincing scientific conclusions.
Although graduation thesis is one of the academic papers, it has its own characteristics compared with academic papers:
The first is guidance. Graduation thesis is a scientific research achievement independently completed under the guidance of tutor. Graduation thesis, as the last assignment before graduation from university, can not be separated from the help and guidance of teachers. Teachers should give specific methodological guidance on how to conduct scientific research and how to write papers. In the process of writing graduation thesis, teachers should inspire and guide students to work independently, pay attention to students' initiative and creativity, help students determine topics, specify references and investigation clues, examine and approve the outline of the thesis, answer difficult questions, guide students to revise the first draft of the thesis, and so on. In order to write a graduation thesis, students must actively exert their intelligence, study hard and complete the task of graduation thesis writing independently.
The second is practice. According to the teaching plan, at the beginning of university, students should concentrate on learning the basic theory, professional knowledge and basic skills of this subject well; In the last semester of college, students should concentrate on writing their graduation thesis. Learning professional knowledge well and writing graduation thesis are unified, and the study of professional basic knowledge lays a solid foundation for writing graduation thesis; The writing of graduation thesis is the application and deepening of professional basic knowledge. Writing a graduation thesis is to use the existing professional basic knowledge to independently carry out scientific research activities, analyze and solve a theoretical or practical problem, and turn knowledge into practical training of ability. The main purpose of writing is to cultivate students' ability to solve practical problems by comprehensively applying what they have learned, so as to prepare for writing academic papers as professionals in the future. In fact, it is a practical academic paper.
The third is the hierarchy. Compared with academic papers, the requirements of graduation thesis are lower. Professional academic papers refer to papers written by professionals for scientific research and expression of scientific research achievements, which generally reflect the latest academic achievements in a certain professional field, have high academic value, and have a certain role in promoting the development of scientific undertakings. Due to various conditions, the quality of college students' graduation thesis is relatively low. This is because: first, college students lack writing experience, most of them are writing papers for the first time, and they know little about the knowledge and skills of writing papers. Second, the scientific research ability of most college students is still in the process of training. During their college years, they mainly studied professional basic theoretical knowledge, lacking the training of using knowledge independently for scientific research. Third, writing graduation thesis is limited by time. Generally, schools arrange graduation thesis in the last semester, but in fact, the time for writing graduation thesis is only about ten weeks. It is difficult to write high-quality academic papers in such a short time. Of course, this does not exclude a few college students from writing high-quality academic papers through their usual accumulation and full preparation.
[5] Zhao Dexiong. On the selection and future development trend of building thermal insulation materials [J]. China New Technology and New Products, 2013,06:190.
Liu Rong, Gao. Research and application progress of new building insulation materials [J]. China Ceramic Industry, 2013,05: 25-28.
[7] Chen Hongbo. Analysis on the environmental protection of building materials [J]. Theoretical research on urban construction. Electronic version, 20 12( 13):37.
Li Lan, on the use of building materials and environmental protection [J]. Journal of China Institute of Environmental Management, 2006, 16(3):47-49.
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