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考虑到不同朝向外墙外表面暴露于周期性的太阳照射辐射和室外环境温度,采用MATLAB矩阵函数求解不同朝向瞬态热传导逐时太阳-空气温度。基于不同朝向逐时太阳-空气温度对北京办公建筑4种墙体材料和4个朝向采用XPS进行外墙外保温,计算全年加热和冷却负荷。基于现值系数最大程度减少加热冷却能耗和保温总成本得到最优保温厚度。对采用最优保温厚度,计算20年寿命周期收益和保温投资回收期。结果表明:冬季南向外墙太阳照射辐射得热最多,最优保温厚度最薄。北向外墙最优保温厚度最厚,采用最优保温厚度寿命周期收益最大。同一朝向不同墙体材料最优保温厚度相差明显,4种墙体材料采用最优保温厚度寿命周期收益从高到低依次为:混凝土、灰砂砖、黏土砖、加气混凝土。同一种墙体材料各朝向寿命周期收益相差较大而保温投资回收期相差不大。
Considering the external exposure to external solar radiation and outdoor ambient temperature, the mathematic function of MATLAB is used to solve the transient temperature-dependent solar-air temperature with different orientations. Based on the different orientation hourly solar-air temperature, four kinds of wall materials and four orientations of Beijing office buildings were adopted for exterior wall external insulation, and the annual heating and cooling loads were calculated. Based on the present value of the coefficient to minimize the heating and cooling energy consumption and the total cost of insulation to get the optimal insulation thickness. The use of the optimal thickness of insulation, life expectancy of 20 years to calculate the return and insulation payback period. The results show that in winter, solar radiation to the outer wall reaches the maximum, and the optimal insulation thickness is the thinnest. The outer wall of the North to the thickest optimal insulation thickness, the optimal insulation thickness of the life cycle of the largest gain. In the same direction, the optimal insulation thickness for different wall materials is obviously different. The best thermal insulation thickness of the four kinds of wall materials is obtained from high to low in the order of concrete, lime sand brick, clay brick and aerated concrete. The same wall material for each life cycle income greater difference and insulation investment recovery period is not much difference.