study on energy saving of external wall thermal insulation based on city green building

1、<p>　　Study on Energy Saving of External Wall Thermal Insulation based on City Green Building</p><p>　　Abstract: In recent years, with the continuous development of society, people’s awareness of energy

2、 conservation has also been enhanced. Among them, building energy consumption occupies a very large proportion in all their energy consumption. Therefore, people have taken various measures to reduce the energy consumpti

3、on of building its own. External wall thermal insulation is a new building energy saving technology. Through verification, application of external wall insulation technology in buil</p><p>　　Keywords: Energy

4、 saving; energy consumption; the external wall insulation technology </p><p>　　0 Introductions </p><p>　　Relating to the external wall thermal insulation material and technology of our country t

5、heory and the technology is still in development stage, but the research fields mainly concentrated in the big city, but in the urban construction in the area less studied, but for China such a big agricultural country,

6、make good use of agricultural resources, to solve the energy problem in most of exterior wall thermal insulation material, moreover, agricultural resources relative industrial resources have </p><p>　　1 Exte

7、rnal wall insulation materials and technology in big city </p><p>　　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 mat

8、erials by high temperature melting into 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

9、 extruded polystyrene board (XPS): it made of extruded polystyrene foam; (5) rigid polyurethane board: the polyurethane is made; (6) phenolic</p><p>　　Six kinds of heat preservation material not only pollute

10、 the larger city, but also have 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: </p><p>

11、;　　2.1 waste plant fiber </p><p>　　Mainly refers to the crop straw, waste wood materials etc.. The first is the function of insulation, there is a lot of good performance, has great potential in development

12、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 envi

13、ronmental protection and energy saving materials. </p><p>　　2.2 bamboos </p><p>　　Bamboo is a kind of can adapt to different climate and plant growth cycle is short, generally only need 5 years

14、can be harvested, used as thermal insulation materials, cast greatly saves energy. </p><p>　　2.3 waste plastic material </p><p>　　Waste plastic is insulation and anti ultraviolet, durability, fi

15、re 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 th

16、e environment, the membrane material is a kind of green building materials applied and popularized vigorously in developed countries. </p><p>　　3 The peripheral structure optimization and material selection

17、</p><p>　　3.1 The shape coefficient design of town residential </p><p>　　The shape coefficient of building is ratio that contact with outside atmospheric appearance area and surrounded by the vo

18、lume 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 us

19、e the formula (L) calculation. </p><p>　　As can be seen from equation (1) and the shape factor of the building is a building underside shapes, layers, building storey buildings related. For low-rise building

20、s, the impact on buildings storey building shape coefficient is particularly evident. According to “Energy conservation design standards “, in order to improve the thermal performance of buildings , requiring controlled

21、shape coefficient of 0.3 or 0.3, but most of the town buildings are unable to meet their requirements , calculated</p><p>　　(2) Appropriate to increase the number of layers of the building can reduce the sha

22、pe coefficient. Increased number of layers building process is less than the incremental increase in the peripheral area surrounding the volume. Therefore, under the functional and economic conditions allow, an appropria

23、te increase in the number of layers of the building, on the shape coefficient control is beneficial. </p><p>　　(3) When the standard floor area is the same, raise deep into the building, will be a correspond

24、ing reduction in shape coefficient relative, right angle and square shape coefficient is minimum. Thus, nearly square building plan for building energy efficiency is beneficial. </p><p>　　(4) A combination o

25、f centralized building compact flat space, reducing bump changes shape coefficient can be reduced. So shape coefficient also has the advantage of small architectural engineering aspects of the economy. </p><p&

26、gt;　　In the case of the shape coefficient determined should be possible to reduce the area of ??the external structure of the main room and the main room as possible to concentrate layout. In addition, different town res

27、idential 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 m

28、any houses dislocation lap, resulting in an increase in shape fac</p><p>　　3.2 Optimization of the window </p><p>　　By testing and analysis showed that the outer doors of the heat transfer accou

29、nts for 30% -40% of the building envelope, the ratio of the energy giant. How many energy-saving windows directly related to the degree of the merits of the building? So small guaranteed sunshine, lighting, ventilation,

30、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 wi</p><p&

31、gt;　　South windows get maximum 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 preva

32、iling wind direction also affects the degree of indoor heat loss and summer indoor natural ventilation. In cold areas surrounding farm house design, most of the main room and the window layout should avoid facing the pre

33、vailing wind direction, in order to avoid excessive heat loss, th</p><p>　　(2) Shape windows </p><p>　　When a certain area of ??the window. Different window shapes and sunshine hours are also af

34、fected 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. </p><p>　　(3) Different buildi

35、ng toward choose a different glass </p><p>　　Cold regions, the south windows to consider more than get the radiant heat of the sun, thermal insulation based design. You can consider using a small hollow glas

36、s heat transfer coefficient of ordinary glass. Due north windows shall not hot, hot sites are lost, wealthy farmers can use low-E windows to prevent the indoor heat dissipated outwards. </p><p>　　In addition

37、, 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

38、 should use a higher strength and can prevent air infiltration panel to protect them. After using paint quadruple glazing energy-saving effect is very obvious, because the heat transfer coefficient is small, reducing the

39、 energy consumption for heating and air-condition</p><p>　　3.3 The design of wall insulation </p><p>　　It can be obtained from the calculation, the heat loss through the walls of buildings accou

40、nted for 22% of total energy consumption. Therefore, to do wall insulation design is very important. According to the current building energy efficiency design standards for residential buildings walls and roof must have

41、 a relatively high thermal resistance (or a relatively low heat transfer coefficient), it can calculated according to the formula (2) thermal transfer flat wall. </p><p>　　Wherein: Ri: The wall inner surface

42、 of?heat?resistance; Re: The out surface of heat resistance; 　　R0- Total resistance; d- The thickness of the material; λ- Thermal conductivity of materials </p><p>　　After calculation that solid red brick w

43、all heat transfer coefficient K=0.758W/(m2?K). According to the engineering construction standards, in the cold area for heat transfer coefficient is 0.3-0.6(w/(m2?K)),Thermal insulation performance of the insulation per

44、formance 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 energy sa

45、ving technology in t</p><p>　　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 concrete

46、 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

47、 itself is conducive to play a protective role against the external environment. The main advantages of</p><p>　　3.4 Design and application of roof insulation materials </p><p>　　The roof Locate

48、d on top of building is covered with effect from the uppermost part of the building component and is the highest in the building envelope suffered outdoor temperature, the area is large, its total energy consumption of b

49、uildings accounts for 9% heat, do good roof insulation for reducing building energy consumption is also very important. Roof and wall energy saving principles, is by improving the thermal performance of roof layers to pr

50、event the transfer of heat. </p><p>　　Data show that high absorption black roofing material, surface and ambient temperature difference may be as high as 50 ℃; while high light reflective roofing materials,

51、the temperature difference of only 11.1 ℃, roof color the more light, the better the energy saving effect. Dark gray reflective roofing is only 8%, while the white linoleum tile and ceramic tile roof sunlight reflectivit