基于火用分析和生命周期评价的既有建筑围护结构节能改造

 为了定量系统地评价既有建筑改造的节能效果，提出了火用分析结合生命周期评价的方法。根据热力学第二定律，将能耗转换为火用，分析建筑生命周期中对能源、资源和环境影响较大的阶段，即建材的生产阶段和运行阶段。运用该方法对宁波建筑节能改造实例进行分析，结果表明，在建筑节能改造后的生命周期内，保温材料在生产阶段的能耗需要15年才能与运行阶段节约的能耗相等，CO2排放量需要16a才能与减排的CO2量相等，但对于保温材料，其在生产阶段消耗的火用，远大于其在运行阶段节约的火用。因此，对于既有建筑节能改造，新增保温材料在生产阶段的能耗和CO2排放量不能忽略。对于建造年代久远的建筑，在进行围护结构节能改造时，应当将改造后的节火用效果、节能效果和环境影响作为一个整体进行综合分析。

Exergy Analysis of the Building Envelope Energy Efficiency Retrofit Based on the Life Cycle Assessment

This paper presents an exergy analysis combined with the life cycle assessment method to systematically and quantitatively evaluate the building envelope energy efficiency retrofit. Based on the second law of thermodynamics, the building energy consumption can be transformed into exergy. The method only analyzes the production stage and the operation stage, which represent a higher impact in terms of energy consumption and environmental impact in the building life cycle. A typical case of the existing building envelope energy efficiency retrofit in Ningbo city is analyzed. The results show that it takes 15 years for the cumulative saved energy consumption in the operation stage to reach the embodied energy of the newly added insulation materials in the production stage. For CO2 emissions, it takes 16 years. The cumulative saved exergy consumption would be difficult to reach the embodied exergy consumption in the life span after retrofit. So the embodied energy and CO2 emissions of the newly added insulation materials in the production stage should not be neglected. For the existing old building, it should be prudent to take any retrofit measures; and the energy and exergy efficiency and environment impact of the retrofit measures should be considered as a whole in analysis.