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ISO中⽣命周期评价标准的四个阶段:定义⽬标和范围、清单分析、 影响评价和解释。
⽬标和范围是对研究意图的声明。⽬标和范围明确指出研究的原因以及研究范围。在清单分析阶段,收集和记录所需的数据(例如,能源使⽤量和温室⽓体排放量)以满⾜既定的⽬标和范围,这个阶段是LCA工作最重要也是最消耗时间和精力的阶段。在影响评价阶段,追查简单的清单结果如温室⽓体排放,过渡到其影响, 例如⽓候变化。最后,在解释阶段审视研究结果,将其转化为研究得出的观点,并且有可能提出改进建议或其他改变以减少影响。
ISO 明确要求⽬标陈述需包括以下四点: (1)预期的应⽤; (2)进⾏研究的原因; (3)受众; (4)结果是否能被⽤于公开发布的对⽐论断。需要回答两个问题,“谁会在意这⼀研究以及在什么情况下在意? (回答这⼀问题涵盖了第 3 和第 4 点) ”和“为什么我们要去做它和我们将要做什么? (回答这⼀问题涵盖了第 1 和第 2 点) ”。LCA 的过程是相互迭代的,随着LCA进程的不断深入,目标和范围可能会需要作出调整。
Goal Definition | What is the purpose of the LCA? Who is the target group? Which decision must the LCA support? What is the extent of these decisions? |
Scope Definition | Which product/solution is to be assessed? What is service provided by the product? How big a part of the product system is to be included? Which environmental exchanges must be ascribe to this service? |
Inventory | What are the data requirements? What is the quality of the collected data? How is the product system modeled? How are the data aggregated and how are the uncertainties handled? |
Impact Assessment | Which resource consumption and environmental impact potential does the product entail? Which contributions are the most important? Which sources are the most important? Which uncertainties and data gaps are the most significant? |
研究范围不仅仅是⼀个单⼀的陈述,⽽是⼀系列表明什么将被纳⼊研究中的定性及定量信息,以及⽤来描述研究是如何完成的所需要的关键参数。ISO 对于范围的要求中列有 12 个独⽴的条⽬,需要在这个阶段陈述清楚有五个条⽬:⽤于研究的产品系统,功能单位,系统边界,产品清单与/或要跟踪的影响评价,其余10个条目会在后几个阶段一一讨论。
功能单位在ISO中定义是:quantified performance of a product system for use as a reference unit.
功能单位必须是⼀种明确和定量的测量,将功能和待研究的输⼊输出值联系在⼀起。例如水泥厂的功能单位就是,“生产一吨水泥”。
在ISO中还提到了Reference flow,“For each of the properties identified as having a determining influence on the amount of product necessary, a relative measure must be determined of the extent to which the studied products are expected to substitute each other.”(对于每一种被确定为对所需产品数量有决定性影响的特性,必须确定一个度量标准,以确定研究产品相互替代的程度。)
未完待续
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