基于墙体材料最优保温厚度研究

Research on optimum insulation thickness based on wall materials

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 outside surface of different orientation exterior wall is exposed to periodic solar radiation and outdoor environmental temperature, MATLAB matrix function is used to solve the hourly solar-air temperature of each orientation exterior of wall transient heat conduction. With XPS as insulation material,the annual heating and cooling transmission load are calculated based on the hourly solar-air temperature for office building with four type of wall materials and four orientations in Beijing. The optimum insulation thickness is achieved by minimizing the heating and cooling energy consumption and the total cost of insulation based on the present worth method. The life cycle saving and insulation payback period are calculated over lifetime of 20 years according to the optimum insulation thickness. The results demonstrate that：in winter the south orientation exterior wall has the highest solar radiation heat gain and the lowest optimum insulation thickness. The highest optimum insulation thickness and highest lifecycle benefit with optimum insulation thickness are found to be north orientation exterior wall. The different type of insulation material has a great disparity on the optimum insulation thicknesses for the same direction. The four type of wall material lifecycle benefit using the optimum insulation thickness from high to low is：concrete, sand lime brick,clay brick,aerated concrete, respectively. The orientation has a great effect on the lifecycle benefit and a small effect on the insulation payback period for the same type of insulation material.