Purpose

An estimation of the environmental impact of buildings by means of a life cycle assessment (LCA) raises uncertainty related to the parameters that are subject to major changes over longer time spans. The main aim of the present study is to evaluate the influence of modifications in the electricity mix and the production efficiency in the chosen reference year on the embodied impacts (i.e., greenhouse gas (GHG) emissions) of building materials and components and the possible impact of this on future refurbishment measures.

Methods

A new LCA methodological approach was developed and implemented that can have a significant impact on the way in which existing buildings are assessed at the end of their service lives. The electricity mixes of different reference years were collected and assessed, and the main datasets and sub-datasets were modified according to the predefined substitution criteria. The influence of the electricity-mix modification and production efficiency were illustrated on a selected existing reference building, built in 1970. The relative contribution of the electricity mix to the embodied impact of the production phase was calculated for four different electricity mixes, with this comprising the electricity mix from 1970, the current electricity mix and two possible future electricity-mix scenarios for 2050. The residual value of the building was also estimated.

Results and discussion

In the case presented, the relative share of the electricity mix GHG emission towards the total value was as high as 20% for separate building components. If this electricity mix is replaced with an electricity mix having greater environmental emissions, the relative contribution of the electricity mix to the total emissions can be even higher. When, by contrast, the modified electricity mix is almost decarbonized, the relative contribution to the total emissions may well be reduced to a point where it becomes negligible. The modification of the electricity mix can also influence the residual value of a building. In the observed case, the differences due to different electricity mixes were in the range of 10%.

Conclusions

It was found that those parameters that are subject to a major change during the reference service period of the building should be treated dynamically in order to obtain reliable results. Future research is foreseen to provide additional knowledge concerning the influence of dynamic parameters on both the use phase and the end-of-life phase of buildings, and these findings will also be important when planning future refurbishment measures.

中文翻译：

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电力结构和生产效率的提高对建筑构件的温室气体排放和未来整修措施的作用

目的

通过生命周期评估（LCA）估算建筑物对环境的影响会增加与参数相关的不确定性，这些参数在较长的时间范围内会发生重大变化。本研究的主要目的是评估所选参考年的电力结构变化和生产效率对建筑材料和构件的具体影响（即温室气体（GHG）排放）的影响以及可能的影响。关于未来的整修措施。

方法

开发并实施了一种新的LCA方法论方法，该方法可以对现有建筑物在使用寿命结束时进行评估的方式产生重大影响。收集并评估了不同参考年的电力混合，并根据预定义的替代标准修改了主要数据集和子数据集。在一栋建于1970年的现有选定参考建筑物上说明了电力混合调整和生产效率的影响。针对四种不同的电力混合计算了电力混合对生产阶段具体影响的相对贡献。 1970年的电力结构，当前的电力结构以及2050年的两种可能的未来电力结构情景。

结果和讨论

在所介绍的案例中，对于单独的建筑构件，电力混合GHG排放相对于总价值的相对份额高达20％。如果用具有更大环境排放的电力混合物代替该电力混合物，则该电力混合物对总排放量的相对贡献可能甚至更高。相反，当经过修改的混合电力几乎被脱碳时，对总排放量的相对贡献可能会降低到可以忽略不计的程度。混合电力的修改也会影响建筑物的残值。在观察到的情况下，由于不同的电混合造成的差异在10％的范围内。

结论

已经发现，应该动态对待那些在建筑物的参考服务期内发生重大变化的参数，以便获得可靠的结果。预计未来的研究将提供有关动态参数对建筑物的使用阶段和使用寿命终止阶段的影响的更多知识，这些发现对于规划未来的翻新措施也将非常重要。