Bio-based building materials and temporary carbon storage

Global warming has become an indisputable phenomenon, thanks to precise temperature measurements taken around the globe and numerous scientific studies, notably compiled by the experts of the IPCC (Intergovernmental Panel on Climate Change) since 1988. Awareness of global warming on the part of public authorities led to the first international conference in Rio in 1992, followed by annual COP (Conference Of the Parties) meetings since 1995, to discuss and commit countries to limiting the average temperature of the earth's surface. COP3 in Kyoto (1997) led to the "Kyoto Protocol", signed and ratified by over 190 states, including all European countries. COP21 in Paris in 2016 led to new commitments on limiting global warming (the Paris agreements).

The building sector in Europe accounts for a significant share of anthropogenic greenhouse gas (GHG) emissions: around 37% by 2022 according to the UN . These GHGs are linked both to the construction of buildings (extraction of raw materials, transport, transformation, implementation on site, maintenance, end-of-life) and to the use of buildings (heating, lighting, cooling, ventilation, domestic hot water, household appliances). On a global scale, use of existing buildings accounts for around three-quarters of emissions, and construction for around a quarter . This is why, since the 1990s, public authorities have mainly focused their regulations on controlling energy use, via thermal regulations. The ultimate aim is to build positive-energy buildings, i.e. passive buildings equipped with energy production systems. Achieving this goal means increasing the quantity or efficiency of insulating materials in building envelopes. The decrease in energy use, accompanied by an increase in the quantity of materials in the walls, is logically focusing more and more attention on materials, their energy content and their environmental impact. In France, this was the subject of the E+C experiment– (positive energy and carbon reduction buildings) between 2016 and 2020, which led to the recommendations of the RE2020, an environmental regulation that takes into account the "global warming" impact of materials chosen in the design phase of structures.

Building materials are often seen as "GHG emitters", in the same way as cementitious materials and steel products. For these sectors, the ecological effort consists in limiting the...