Purpose

Previous life cycle assessments (LCAs) of buildings and building components show a broad range of values for theimpact of maintenance and replacement, some highlighting these operations as major hotspots while others consider theminsignificant. This article highlights methodological aspects explaining this discrepancy. The influence of three aspects isinvestigated further in a case study of façade materials: the reference study period (RSP), service life data, and the use of around-up number of operations or annualized impacts.

Methods

A 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 fromindustry practitioners and low, standard and high values from a generic database), and two possible calculation methods (round-up or annualized impacts).

Results and discussion

While the same façade alternative had the lowest GWP in all cases, different methodological choicessignificantly affected the GWP and respective ranking of other alternatives. Some alternatives showed a significant increasein GWP over longer RSPs, while others were still dominated by the impact of initial production after 200 years. In nearlyall cases, generic service life data lead to a higher GWP than data from industry practitioners. Major discrepancies werefound between generic and practitioner data in some cases, e.g., for the brick façade. In most cases, annualized impacts ledto a slightly lower (or equal) GWP than using a round-up number of operations. However, when a major operation happensshortly before the end of the RSP, the annualized method leads to considerably lower GWP.

Conclusions

Maintenance and replacement are rarely significant over a 50-year RSP but sometimes become hotspots overlonger RSPs. Using round-up operations or annualized impacts does not make much difference in average, but leads to significantlydifferent results in specific cases. As building LCA enters certification and regulation, there is a need to harmonizesuch methodological choices, as they affect LCA results, hotspot identification, and recommendations. Discrepancies inservice life data also call for the gathering of reliable data.