Abstract
PurposeAn 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.MethodsA 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 discussionIn 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%.ConclusionsIt 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.
Highlights
Construction has been identified as one of the most important target sectors to be tackled in order to reduce climate change and its effects
The present study confirmed that the electricity mixes used in the production of buildings can significantly influence the calculated values for the environmental impacts of buildings in need of refurbishment
Our results from calculations in the case of an apartment building showed that the contribution of emissions from the electricity mixes of different time periods could be as high as 20% in the context of individual materials
Summary
Construction has been identified as one of the most important target sectors to be tackled in order to reduce climate change and its effects. This has been highlighted in the reports published by the UN Environment (UN Environment Programme 2018; UNEP 2020), the International Energy Agency (IEA and UNEP 2019), and the International Panel on Climate Change (IPCC 2018), among others (Wu et al 2017). These reports have indicated that buildings have. Refurbishment of the existing building stock has been recognized as one of the key future tasks for reducing the environmental impacts associated with buildings (Anand and Amor 2017; EC 2020)
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