Retrofit as a carbon sink: The carbon storage potentials of the EU housing stock

In the next decades, a large share of residential buildings in EU-28 is expected to be renovated to achieve the 2 °C target requested by the Paris Agreement by 2050. Bio-based materials used for increasing the thermal insulation and temporary store carbon in construction elements might be a valuable opportunity that can contribute to accelerate the transition to a zero-carbon society. This article investigates the effect of massively storing carbon in bio-based construction products when used for the renovation of existing facades. Five alternative construction solutions were compared, three with a large amount of fast-growing biogenic material used as insulation, one with timber used for the frame and additional fibrewood as insulation, and the last one with synthetic insulation. A statistic-based Geocluster model was developed to predict the future material flow for building renovation in EU-28 and a dynamic life cycle assessment performed in order to verify the contribution of construction materials in reducing/increasing the carbon emissions over time. The results show that fast-growing biogenic materials have an increased potential to act as a carbon sink compared to timber. In particular, if straw is used as an insulation material, the capacity to store carbon from the atmosphere is effective in the short-term, which represents an important strategy towards the Paris climate Agreement goals.