The Saint-Gobain subsidiary ISOVER (Saint-Gobain) is positioning itself with a revised mineral wool product line as a provider of energy-efficient and circular economy-capable insulation materials. The focus is on glass wool products with high recycled content that meet the tightened requirements of the GEG — Building Energy Act from 2025 and the upcoming EU Taxonomy thresholds. The product strategy targets new construction in the KfW Efficiency House segment as well as energy retrofitting of existing buildings.

Product line: Focus on Lambda value and recycling rate

ISOVER offers glass wool insulation materials with Lambda values (λ) between 0.032 and 0.040 W/(m·K), which vary depending on raw density and application. The model series Integra, Ultimate and Topdec cover rafter cavity, between-rafter and façade insulation. The product lines are certified according to DIN 4108-10 for thermal protection and DIN EN 13162 for mineral wool.

Compared to conventional glass wool, the recycled content of ISOVER products ranges between 45% and 84%, depending on the availability of regional waste glass sources. Manufacturing uses binders based on renewable raw materials, which improves EPD — Environmental Product Declaration values in the GWP categories (Global Warming Potential). In category A1–A3 (Cradle-to-Gate), typical values range from 3.5 to 6.0 kg CO₂-eq/kg, depending on product thickness and raw density.

Market position versus ROCKWOOL, Knauf and Ursa

In the German insulation market, ISOVER competes with ROCKWOOL (stone wool), Knauf (glass wool and EPS) and Ursa (also Saint-Gobain Group, but as an independent brand). ROCKWOOL focuses on stone wool with higher raw density and better fire protection class (A1 non-combustible), while ISOVER scores with lower thermal conductivity and lower weight – relevant for lightweight timber frame construction and renovations with limited load-bearing capacity.

According to industry analyses, ISOVER holds approximately 18–22% market share in the DACH region for mineral wool insulation materials (glass wool segment). ROCKWOOL dominates with around 30% in the stone wool segment, but has a higher production CO₂ footprint due to energy-intensive basalt melting. Knauf holds around 15% market share and differentiates itself through integrated systems with gypsum boards and plaster bases.

Recent developments: EPD update and bio-based binders

In 2024, ISOVER published a revised EPD series according to EN 15804+A2, which for the first time also includes Module D (recycling potential). The data show a net savings potential of up to 1.2 kg CO₂-eq/kg in material recycling, which is relevant for circular building. In pilot projects, ISOVER is also testing fully bio-based starch-based binders, which are intended to further reduce formaldehyde emission levels.

In the product announcement area, the market launch of a new between-rafter insulation board with integrated vapor barrier is planned for 2025. The system is intended to bring the U-value of pitched roofs to below 0.14 W/(m²·K) and thus meet Passive House requirements. At the same time, ISOVER is expanding the availability of blow-in glass wool insulation for hollow space renovations, a growing segment in existing buildings.

Regulatory outlook: GEG 2025 and EU Taxonomy

The GEG amendment 2025 tightens the requirements for primary energy demand of new buildings by approximately 18%. This increases the pressure on insulation materials with low lambda values and low embodied emissions. Additionally, from 2027 onwards, all building products that fall under the EU Taxonomy must meet sustainability criteria – including recyclability and CO₂ limits. ISOVER is comparatively well positioned here with EPD-certified products and high recycled content, but must continue to improve in binder chemistry to be considered fully circular in the long term.

One remaining risk is dependence on waste glass availability: as demand for recycled content increases, supply bottlenecks could raise production costs. Architects and planners should therefore check the EPD specifications of modules A1–A3 and Module D in tenders and base their decisions not just on recycled content, but also on net climate impact.

Further details on specific applications can be found in the article Which ISOVER insulation materials are suitable for which application?.