Dissertation > Industrial Technology > Building Science > Building structure > The structure of the soil, brick, stone,bamboo,wood > Bamboo,wood structure > Wooden structure

Research on Energy-efficiency in Light-frame Wood Residence and the Wall Heat Transfer

Author WangXiaoHuan
Tutor FeiBenHua
School Chinese Academy of Forestry
Course Wood Science and Technology
Keywords wood light-frame residence energy-efficiency composite wall heat transfer coefficient numerical calculation
CLC TU366.2
Type PhD thesis
Year 2009
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Light-frame wood residence can create a good living environment with advantages of environment-friend, energy-efficiency, structural safety, health and comfort. Therefore, they not only can contribute to human in saving energy source and protecting zoology, but also can provide superior living environment to improving people living comfort, which can be popularized in the course of residence industrialization, especially in the integration of urban-rural areas.Energy efficiency in residence buildings is an important part in today’s energy boom of architecture, and energy efficiency of the light-frame wood residence is the basic premise to promote to application. In this research energy efficiency was evaluated based on field testing for the light-frame wood residence in Beijing, including energy consume, wall insulation performance, and regulation performance of temperature and humidity; insulation performance of wood frame walls was studied under the conditions of steady-state performance using heat flow meter and hot-box test method, which were fabricated used domestic materials; through numerical calculation, heat transfer regularity of the temperature distribution in the wall was observed.The main results of the dissertation are summarized as follows:1 Energy-efficiency effect in light-frame wood residence is significant, and the regulation performance of temperature and humidity is well in living space.(1)Electricity consumption in wood structure and brick-concrete structure used for residence heating respectively was 120kWh/(m2·a) and 324 kWh/(m2·a). Light-frame wood residence save energy 63% than brick-concrete structure, and save energy 48% than Harbin’s insulation composite brick-concrete structure, also save energy10% than its same frame structure.(2)The average effective heat transfer coefficient of light-frame wood wall was 0.217 W/(m2·K), its lower 52% than current standard limit of energy-efficiency 65% in our country.(3)In residence 1- light-frame wood house, the indoor temperature was 5.7℃~31.0℃, and the average relative humidity was 33%~75% on the first floor; the indoor temperature was 6.7℃~34.6℃, and the average relative humidity was 31%~66% on the second floor. In residence 2- glued laminated timber house, the indoor temperature was 0.8℃~37.2℃, and the average relative humidity was 59%~76% on the second floor. In residence 3- glued laminated timber house, the indoor temperature was -2.4℃~19.8℃, and the average relative humidity was 40%~44% on the second floor. The insulation performance of light-frame wood house was better than glued laminated timber house in un-heating conditions in winter; the variation of relative humidity of glued laminated timber house was the most stable in un-refrigeration conditions.(4)Temperature inner light-frame was higher than indoor and outdoor temperature in March to October. But higher than outdoor temperature about 11℃and lower than indoor temperature about 3℃in November to January, and along the wall from outside to inside, temperature showed an increasing trend. The wall has an excellent thermal insulation in winter and summer, which was helpful for homogeneous distribution of indoor air temperature. The variation regularity of relative humidity was contrary to temperature, and the relative humidity of inner wall was below than it’s of inside and outside.(5)In the hottest and the coldest month, indoor temperature change rate of all residence was less 0.5, and the minimum amplitude of the indoor relative humidity was 11%, the maximum was 35%. According the distribution of delay time of the indoor temperature and relative humidity, the regulation performance of temperature and humidity was well in light-frame wood residence; delay time of relative humidity was longer in glued laminated timber house in summer, and the amplitude was small.2 The insulation performance of the light-frame wood walls is excellent, which are manufactured by the plantation wood, therefore this kind of wall can be actively promoted to application.(1)Heat transfer coefficient of No.1, No.2, No.3, and No.6 was 0.489~0.529W/(m2·K), others were less 0.4 W/(m2·K). The insulation properties of the experimental structure walls were qualified to the technical code for wood construction and partitions with timber frame- work used in reinforced concrete frame. Especially heat transfer coefficient of the walls of No.12 and No.13, when they were used in more cold areas, the energy-saving effect was significant.(2)Data were more reliable when hot box-heat flow meter was used to test the insulation performance. Effective heat transfer coefficient should be used to describe the insulation performance of light-frame wood wall.(3)The resistance could be increasing at least 2 times, if the cavity between the wood stud was filled with Rockwool. Plywood could be effective to reduce heat transfer coefficient 6%; expandable polystyrene(EPS) could reduce its 26%; extrude polystyrene (XPS) could reduce its 36%; 45×140mm dimension wood stud could reduce wall heat transfer coefficient 6%~32% than 45×90mm dimension wood stud, and the resistance to heat was more enhanced.3 Numerical calculation can be used to accurately describe temperature distribution of internal interface in the light-frame wood wall.(1)Temperature distribution of internal interface could be calculated used numerical method. The results were agreed approximately with experiment value, so the numerical value could estimate heat transfer visually and effectively.(2)The wall insulation effect as the components was determined by cavity fill with Rockwool and cladding outside with extruded polystyrene board and expandable polystyrene board. Timber as a framework material had resistance effect to temperature fluctuations outside.(3)Temperature distribution of could be calculated in each compound interface of light-frame wood wall by numerical method. This can provide information helpful for the energy-efficient design, because the long-term properties of the wall structure could be predicted by architect in varieties of climatic conditions.

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