Life cycle assessment (LCA) is an internationally accepted method to assess the environmental impacts of buildings. A major methodological challenge remains the modelling of the end-of-life stage of buildings and allocation of benefits and burdens between systems. Various approaches are hence applied in practice to date. This paper compares the two methods widely renowned in Europe—the EC product environmental footprint (PEF) method and the CEN standards: EN 15804+A1 and EN15978—and offers insights about their fitness for achieving circularity goals. The EC PEF method and the CEN EN 15804/EN 15978 standards were methodologically analysed with a focus on the end-of-life modelling and allocation approach and were applied to a building case study. The EN 15804+A1 standard explains the guidelines but does not offer a modelling formula. Accordingly, this paper proposes a formula for the CEN standards using identical parameters as in the end-of-life circular footprint formula (CFF) of the EC PEF Guidance v6.3 to increase consistency among LCA studies. The calculation formulas were then applied to a newly constructed office building. A comparative analysis of both the implementation and results are described, and recommendations are formulated. In the absence of databases compatible with the two LCA methods and comprising all building products, the Ecoinvent datasets had to be remodelled to enable a comparative modular assessment. This proved to be a laborious process. The EC PEF method and CEN standards showed similar impacts and hotspots for the case study building. The module D in the CEN standards includes a significant share of positive impacts, but due to collective accounting, it does not clearly communicate these benefits. The summation of burdens and benefits in the EC PEF method reduces its transparency, while the allocation and quality factors enable this method to better capture the market realities and drive circular economy goals. The construction sector and the LCI database developers are encouraged to create the missing LCA databases compatible with the modular and end-of-life allocation modelling requirements of both methods. More prescriptive and meticulous guidelines, with further harmonization between the EC PEF method and the CEN standards and their end-of-life allocation formula, would largely increase comparability and reliability of LCA studies and communications. To improve transparency, it is recommended to report the module D impacts per life cycle stage as per the CEN standards and the burdens and benefits separately for each life cycle stage as per the EC PEF method.

中文翻译：

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建筑物的报废建模以支持更明智的决策以实现循环经济目标

生命周期评估（LCA）是一种国际公认的评估建筑物环境影响的方法。一个主要的方法学挑战仍然是对建筑物的使用寿命结束阶段以及系统之间的收益和负担分配进行建模。因此，迄今为止在实践中应用了各种方法。本文比较了在欧洲广为人知的两种方法——EC 产品环境足迹 (PEF) 方法和 CEN 标准：EN 15804+A1 和 EN15978——并提供有关它们实现循环目标的适用性的见解。对 EC PEF 方法和 CEN EN 15804/EN 15978 标准进行了方法论分析，重点是寿命终止建模和分配方法，并应用于建筑案例研究。EN 15804+A1 标准解释了这些准则，但没有提供建模公式。因此，本文为 CEN 标准提出了一个公式，该公式使用与 EC PEF 指南 v6.3 的生命周期终止循环足迹公式 (CFF) 中相同的参数，以提高 LCA 研究之间的一致性。然后将计算公式应用于新建的办公楼。描述了实施和结果的比较分析，并提出了建议。在缺乏与两种 LCA 方法兼容并包含所有建筑产品的数据库的情况下，Ecoinvent 数据集必须重新建模以进行比较模块化评估。事实证明这是一个费力的过程。EC PEF 方法和 CEN 标准对案例研究建筑显示出类似的影响和热点。CEN 标准中的模块 D 包括很大一部分积极影响，但由于集体核算，它没有清楚地传达这些好处。EC PEF 方法中的负担和收益的总和降低了其透明度，而分配和质量因素使该方法能够更好地捕捉市场现实并推动循环经济目标。鼓励建筑部门和 LCI 数据库开发人员创建与两种方法的模块化和报废分配建模要求兼容的缺失 LCA 数据库。更加规范和细致的指导方针，以及 EC PEF 方法和 CEN 标准及其寿命终止分配公式之间的进一步协调，将在很大程度上提高 LCA 研究和交流的可比性和可靠性。为了提高透明度，