Abstract
PurposePrevious life cycle assessments (LCAs) of buildings and building components show a broad range of values for the impact of maintenance and replacement, some highlighting these operations as major hotspots while others consider them insignificant. This article highlights methodological aspects explaining this discrepancy. The influence of three aspects is investigated further in a case study of façade materials: the reference study period (RSP), service life data, and the use of a round-up number of operations or annualized impacts.MethodsA comparative LCA of seven façade alternatives is carried out as an illustrative case study. For each alternative, global warming potential (GWP) is calculated using three possible RSPs, four possible material service lives (one from industry practitioners and low, standard and high values from a generic database), and two possible calculation methods (round-up or annualized impacts).Results and discussionWhile the same façade alternative had the lowest GWP in all cases, different methodological choices significantly affected the GWP and respective ranking of other alternatives. Some alternatives showed a significant increase in GWP over longer RSPs, while others were still dominated by the impact of initial production after 200 years. In nearly all cases, generic service life data lead to a higher GWP than data from industry practitioners. Major discrepancies were found between generic and practitioner data in some cases, e.g., for the brick façade. In most cases, annualized impacts led to a slightly lower (or equal) GWP than using a round-up number of operations. However, when a major operation happens shortly before the end of the RSP, the annualized method leads to considerably lower GWP.ConclusionsMaintenance and replacement are rarely significant over a 50-year RSP but sometimes become hotspots over longer RSPs. Using round-up operations or annualized impacts does not make much difference in average, but leads to significantly different results in specific cases. As building LCA enters certification and regulation, there is a need to harmonize such methodological choices, as they affect LCA results, hotspot identification, and recommendations. Discrepancies in service life data also call for the gathering of reliable data.
Highlights
Various estimates indicate that buildings are responsible for 20–40% of global greenhouse gases (GHG) emissions (depending on the scope of the building sector and the Communicated by Holger Wallbaum.Life cycle assessment (LCA) is a widely studied tool to assess global warming potential (GWP) in the building sector (Hauschild et al 2017)
Operational energy use has traditionally been highlighted as the main hotspot of GWP in the life cycle of most buildings, recent studies indicate a rising importance of the relative contribution of embodied emissions, i.e., emissions caused by the production, transport, installation, maintenance, and disposal of construction materials
This paper investigates the modeling of maintenance and replacement of materials in building LCA
Summary
Various estimates indicate that buildings are responsible for 20–40% of global greenhouse gases (GHG) emissions (depending on the scope of the building sector and the Communicated by Holger Wallbaum.Life cycle assessment (LCA) is a widely studied tool to assess global warming potential (GWP) in the building sector (Hauschild et al 2017). Operational energy use has traditionally been highlighted as the main hotspot of GWP in the life cycle of most buildings, recent studies indicate a rising importance of the relative contribution of embodied emissions, i.e., emissions caused by the production, transport, installation, maintenance, and disposal of construction materials. This change is partly explained by improvements in energy performance and a decarbonization of the energy supply (Anand and Amor 2017; Birgisdottir et al 2017; Blengini and Di Carlo 2010; Buyle et al 2013; Chastas et al 2018). The present paper considers a different building element (the façade) and uses a different approach to investigate variability related to the choice of reference study period (RSP), calculation method, and service life data source
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