Impact of GHGs temporal dynamics on the GWP assessment of building materials: A case study on bio-based and non-bio-based walls

International audienceIn a static Life Cycle Assessment (LCA), the global warming potential (GWP) is calculated assuming Green House Gas (GHG) impact to be independent of their emission or uptake timing.This study investigates if this approach is adequate to fully capture the global warming impact (GWI) of building materials. Static LCA (sLCA) was compared to dynamic LCA (dLCA) on two case studies, a conventional wall made of concrete and mineral wool, and a bio-based wall made of wood and straw.The main results are:●sLCA do not allow to evaluate the real GWI of building materials. This might mislead the comparison of building materials.●GWP indicator might be estimated at 100- and 500-year-TH to better support mitigation in the building sector;●The relative metric in kgCO2 equivalent misleads conclusions. Absolute global warming indicators calculated with dLCA might be fairer to compare building materials’ GWI;●sLCA with at 100 years GWP indicator and a relative metric in kgCO2e, which is the approach currently used in the French building sector, disadvantages bio-based solutions compared to conventional ones;●dLCA applied to an alternative functional unit — maintaining a housing function during several centuries — demonstrates that temporary carbon storage induced by bio-based materials do not lead to dramatic carbon release for future generations