RE2020 and bio-based insulation: how to maximize carbon storage in your projects?

RE2020: Understanding the New 2025 Carbon Thresholds

Ic construction and Ic energy indicators: the new regulatory values

RE2020 imposes two progressive carbon indicators until 2031.The construction Ic measures the carbon impact of materials throughout the building's life cycle. Since January 2025, the maximum thresholds have been set at 530 kg CO₂eq/m² for single-family homes (compared to 640 in 2022) and 650 kg CO₂eq/m² for multi-family homes (compared to 740)¹. These values will decrease further in 2028 and 2031, with a target of reducing emissions in^{the sector} by more than 30%².The energy IC, which assesses the impact of energy consumption, remains stable at 160 kg CO₂eq/m² for single-family homes but decreases dramatically for multi-family homes connected to an urban network.

Life cycle assessment (LCA): a mandatory calculation that changes everything

LCA assesses the environmental impact of a building from its construction to its demolition. This mandatory analysis now includes the manufacture, transport, implementation, use, and end of life of materials. FDES (Environmental and Health Declaration Forms) are becoming essential for justifying specification choices. Since the end of 2025, the EN 15804+A2 standard has been in force, generating an increase of around 50 kg CO₂eq in^{the construction Ic3}. To offset this additional constraint, specifiers must give preference to individual or collective FDES and move towards less carbon-intensive materials.

Bio-based insulation: the key to earning carbon credits

cellulose insulation conventional insulation: carbon footprint comparison

The figures speak for themselves. cellulose insulation has a carbon footprint of only 1.5 kg CO₂eq per kg of product, compared to 4 kg CO₂eq/kg for^glass wool. To insulate 100 m² of unused attic space at R=8, the difference amounts to nearly 700 kg of CO₂ saved by choosing cellulose insulation over^mineral wool. Even more impressive: thanks to its raw material derived from recycled paper, cellulose insulation 1.52 kg of CO₂ per kg of paper throughout its lifetime, giving it a^negative carbon footprint. Mineral wool, on the other hand, requires considerable primary energy to manufacture: 184 kWh/m² for rock wool, 59.4 kWh/m² for glass wool, compared to only 17 kWh/m² for cellulose insulation^insulation.

FDES and PEP: valuing stored biogenic carbon (StockC)

RE2020 introduces the StockC (Stored Biogenic Carbon) indicator, expressed in kg C/m² of surface area. Although not yet regulatory, this indicator promotes bio-based materials that sequester atmospheric CO₂ through^{photosynthesis}. The FDES for cellulose insulation this carbon storage from stage A1 (supply). For a 100 m² house insulated with 1 ton of cellulose insulation (i.e., 900 kg of paper), this represents 1,370 kg of CO₂ equivalent stored over the lifetime of^{the building}. By favoring individual or collective FDES rather than penalizing default environmental data (DED), you maximize your carbon gain and facilitate compliance with the 2025 thresholds.

Prescription strategies to optimize your projects

Thicknesses and thermal resistance: correct sizing

RE2020 does not impose any regulatory thickness requirements but does require appropriate thermal resistance: R ≥ 8 m²·K/W for unused attic space and R ≥ 6 m²·K/W for^converted attic space. With a thermal conductivity of 0.038 to 0.040 W/(m·K), cellulose insulation achieve these performance levels with thicknesses of 200 to 320 mm, depending on the application. Optimizing the dimensions reduces the amount of material required while still meeting the thresholds: for the same resistance R=7, cellulose insulation requires a lower applied density than conventional insulation, generating less carbon impact.

A winning combination: bio-based materials + carbon-free energy systems

To maximize carbon points, combine bio-based insulation with decarbonized energy systems: heat pumps, solar thermal, wood energy, or connection to a district heating network. This comprehensive approach reduces both the construction Ic (thanks to the materials) and the energy Ic (thanks to the equipment). cellulose insulation also cellulose insulation in terms of summer comfort, a RE2020 criterion measured by the DH (degree-hour) indicator. Its high phase shift time (up to 10 hours for R=7) keeps heat out during hot hours, limiting the use of air conditioning and^associated emissions.