1、1Study on Energy Saving of External Wall Thermal Insulation based on City Green BuildingAbstract: In recent years, with the continuous development of society, peoples awareness of energy conservation has also been enhanced. Among them, building energy consumption occupies a very large proportion in
2、all their energy consumption. Therefore, people have taken various measures to reduce the energy consumption of building its own. External wall thermal insulation is a new building energy saving technology. Through verification, application of external wall insulation technology in building energy s
3、aving greatly reduces the energy consumption of buildings. This paper mainly introduced on the city building external wall thermal insulation technology and some related measures. Keywords: Energy saving; energy consumption; the external wall insulation technology 0 Introductions Relating to the ext
4、ernal wall thermal insulation material and technology of our country theory and the technology is still in development stage, but the research fields mainly 2concentrated in the big city, but in the urban construction in the area less studied, but for China such a big agricultural country, make good
5、 use of agricultural resources, to solve the energy problem in most of exterior wall thermal insulation material, moreover, agricultural resources relative industrial resources have little pollution to the environment, but the price is cheaper, more suitable for consumption in developing countries,
6、is also an important strategy for sustainable development. 1 External wall insulation materials and technology in big city At present, the main use of big city wall thermal insulation material has six kinds: (L) rock wool board: it is made basalt as main raw materials by high temperature melting int
7、o the fiber and curing processing; (2) glass cotton: chemical composition of glass; (3) expansion of polystyrene board (EPS): adiabatic mold plastic polystyrene foam plastic; (4) the extruded polystyrene board (XPS): it made of extruded polystyrene foam; (5) rigid polyurethane board: the polyurethan
8、e is made; (6) phenolic insulation board: it made of phenolic foam insulation materials; these are the basic polymer, its production, processing and use process not only cost a 3large amount of energy, serious environmental pollution will. In a big city, 85% building selection of external thermal in
9、sulation technology, it is the thermal insulation materials placed outside the main building structure, in order to achieve the purpose of preservation. 2 Suitable for external wall construction insulation materials Six kinds of heat preservation material not only pollute the larger city, but also h
10、ave the high cost, backward technology. From the point of view of urban resources, the following can be used as raw material for exterior wall thermal insulation material: 2.1 waste plant fiber Mainly refers to the crop straw, waste wood materials etc. The first is the function of insulation, there
11、is a lot of good performance, has great potential in development and application of environmental protection and energy saving in building materials. The straw fiber insulation materials processing raw material is simple and fast, no environmental pollution, can be called a green environmental prote
12、ction and energy saving materials. 2.2 bamboos Bamboo is a kind of can adapt to different climate and 4plant growth cycle is short, generally only need 5 years can be harvested, used as thermal insulation materials, cast greatly saves energy. 2.3 waste plastic material Waste plastic is insulation an
13、d anti ultraviolet, durability, fire and other excellent characteristics, the secondary utilization, not only the material utilization, and achieve the energy-saving effect. The membrane material of chemical stability, no pollution and human damage to the environment, the membrane material is a kind
14、 of green building materials applied and popularized vigorously in developed countries. 3 The peripheral structure optimization and material selection 3.1 The shape coefficient design of town residential The shape coefficient of building is ratio that contact with outside atmospheric appearance area
15、 and surrounded by the volume of buildings. The appearance of building area is greater, the greater the radiating surface, under the same other conditions, energy consumption of building shape coefficient increases with the growth of. Usually use the formula (L) calculation. 5As can be seen from equ
16、ation (1) and the shape factor of the building is a building underside shapes, layers, building storey buildings related. For low-rise buildings, the impact on buildings storey building shape coefficient is particularly evident. According to “Energy conservation design standards “, in order to impro
17、ve the thermal performance of buildings , requiring controlled shape coefficient of 0.3 or 0.3, but most of the town buildings are unable to meet their requirements , calculated by the formula (l) got now typical Harbin shape coefficient is about 0.75 farmers , unable to meet the requirements of the
18、 standard . According to the research data indicate that shape coefficient increased 0.01 per heat consumption index increased by about 2.5%. Therefore, strict control of building shape factor for building energy efficiency is very important. After checking shows that the bottom area of ?the shape c
19、oefficient of various shapes in descending order are: triangle, rectangle, square, hexagon, and round. So, circular and polygonal is beneficial for energy, and energy-saving triangle is unfavorable. So in order to serve the purpose of energy conservation, reduce indoor heat loss should be combined w
20、ith the use of the function, select the appropriate plane shape, try to avoid uneven shape, measures 6often used are: (l) For the purpose of energy-saving construction, a joint column for each additional unit, that will reduce building a wall, its exterior wall area shrinks, also a corresponding red
21、uction in shape factor. So for energy-efficient building design, the appropriate number of dwelling units linked columns of shape factor control is beneficial. (2) Appropriate to increase the number of layers of the building can reduce the shape coefficient. Increased number of layers building proce
22、ss is less than the incremental increase in the peripheral area surrounding the volume. Therefore, under the functional and economic conditions allow, an appropriate increase in the number of layers of the building, on the shape coefficient control is beneficial. (3) When the standard floor area is
23、the same, raise deep into the building, will be a corresponding reduction in shape coefficient relative, right angle and square shape coefficient is minimum. Thus, nearly square building plan for building energy efficiency is beneficial. (4) A combination of centralized building compact flat space,
24、reducing bump changes shape coefficient can be reduced. So shape coefficient also has the advantage of small architectural engineering aspects of the economy. 7In the case of the shape coefficient determined should be possible to reduce the area of ?the external structure of the main room and the ma
25、in room as possible to concentrate layout. In addition, different town residential dislocation lap would increase the area of the building exterior envelope. Appropriate regulation units to avoid increasing the shape factor. Due to the homestead, a lot of houses and do not connect, there are many ho
26、uses dislocation lap, resulting in an increase in shape factor. 3.2 Optimization of the window By testing and analysis showed that the outer doors of the heat transfer accounts for 30% -40% of the building envelope, the ratio of the energy giant. How many energy-saving windows directly related to th
27、e degree of the merits of the building? So small guaranteed sunshine, lighting, ventilation, landscape required conditions should minimize the area of ?the outer door and window openings, the windows increase air tightness, reducing cold penetration, improve its insulation properties of the window,
28、the window itself to reduce the heat transfer. Conducting building energy design should deal with each of the key issues facing the window configuration, size, and structure and insulation measures. Concrete can be achieved by the 8following aspects. (l) The windows facing South windows get maximum
29、solar radiation heat in the winter, and summer heat radiation is greater than the thing to the south. Therefore, the use of south-facing windows can get cool effects. In addition, the prevailing wind direction also affects the degree of indoor heat loss and summer indoor natural ventilation. In cold
30、 areas surrounding farm house design, most of the main room and the window layout should avoid facing the prevailing wind direction, in order to avoid excessive heat loss, the impact of indoor temperature. (2) Shape windows When a certain area of ?the window. Different window shapes and sunshine hou
31、rs are also affected on the indoor area. Indoor sunshine analyzes that elongated windows with more hours of sunshine in winter. Thereby increasing the heat buildings acquired to save energy. (3) Different building toward choose a different glass Cold regions, the south windows to consider more than
32、get the radiant heat of the sun, thermal insulation based design. You can consider using a small hollow glass heat transfer coefficient of ordinary glass. Due north windows shall not hot, hot sites are lost, wealthy farmers can use low-E windows to 9prevent the indoor heat dissipated outwards. In ad
33、dition, the filler can be used to improve the thermal insulation effect of the door. Optional polystyrene board insulation materials, glass wool, rock wool board, mineral wool board, such as efficient insulation materials, and should use a higher strength and can prevent air infiltration panel to pr
34、otect them. After using paint quadruple glazing energy-saving effect is very obvious, because the heat transfer coefficient is small, reducing the energy consumption for heating and air-conditioning cooling consumption, computing available in the winter to save heating energy 50.77%, summer cooling
35、consumption savings 15.59%. 3.3 The design of wall insulation It can be obtained from the calculation, the heat loss through the walls of buildings accounted for 22% of total energy consumption. Therefore, to do wall insulation design is very important. According to the current building energy effic
36、iency design standards for residential buildings walls and roof must have a relatively high thermal resistance (or a relatively low heat transfer coefficient), it can calculated according to the formula (2) thermal transfer flat wall. Wherein: Ri: The wall inner surface of?heat?resistance; Re: 10The
37、 out surface of heat resistance; R0- Total resistance; d- The thickness of the material; - Thermal conductivity of materials After calculation that solid red brick wall heat transfer coefficient K=0.758W/(m2?K). According to the engineering construction standards, in the cold area for heat transfer
38、coefficient is 0.3-0.6(w/(m2?K),Thermal insulation performance of the insulation performance requires roughly the equivalent of red brick 1.5m thickness of the wall, apparently relying solely on traditional wall materials to meet the requirements of building energy-saving is unlikely. The wall energ
39、y saving technology in the present stage in our country is divided into single wall and composite wall energy saving technology. In the course of the study in this paper, the use of sandwich insulation technology for energy-saving technology to optimize the farm house: In the middle of reinforced co
40、ncrete or block walls located rockwool board, mineral wool board, glass wool board or fill bulk perlite, polystyrene particles, glass wool, the insulating material is disposed in the middle of the external walls, wall material itself is conducive to play a protective role against the external environment. The main advantages of the sandwich insulation wall insulation is
