Life cycle assessment of timber high-rise building structures : Case study of a project examined in the context of French environmental regulation (RE2020)

Abstract: The damages that the building sector does to the environment can no longer be ignored and need to be approached with a life cycle assessment (LCA). Advantages to build in wood and to build dense cities lead to a potential “two birds in one stone” effect regarding high-rise massive timber construction. The aim of this study is to apply a hands-on approach to assess the relevancy of high-rise massive timber construction. The assessment is based on data from an actual building project settling in a French context regarding the regulation on new constructions carbon and fire safety regulation (RE2020). The LCA is found on the following functional unit: “the structural support of a 100 m-high building, replying to fire-safety objectives”, and is assessed based on the RE2020 framework using a so-called “dynamic” LCA emissions accounting. For a good understanding of the impacts of this methodology and for a better and broader comparison of this study to other studies found in literature, the LCA result is reported based on a traditional ‘static’ emission accounting approach. The life cycle inventory (LCI) covers the structure and other techniques to protect the building from fire, and the global warming potential GWP data are gathered from FDES environmental product declaration (EPD) gathered from the INIES database. Results point unequivocally at a lower GWP of the timber structure under any circumstance: both when compared to Business-as-usual construction and to a concrete equivalent of this precise project and compared in static or so-called “dynamic” LCA. The timber structure is the only analysed solution that meets any (and even all) of the thresholds imposed in RE2020. The so-called “dynamic” LCA leads to a wider gap between timber and concrete structures. The timber building alternative results in lowest climate impact (GWP) related to both emissions of green house gases and biogenic carbon storage in the construction. Other environmental impact categories are not explored which represents a limitation to the conclusion of this study.