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Plant-based fibers: an ecological and efficient alternative for building insulation

In the family of bio-based materials for construction application, flexible insulation made from plant fibers is experiencing particularly dynamic growth, driven by the wave of “greening” of buildings. While they still only represent 3% * of the insulation market in terms of value (excluding wood), their technical performance now challenges conventional products, and the ecological transition is working in their favour. A major player in this young sector, Cavac Biomatériaux, a subsidiary of the Cavac agricultural cooperative which dared to diversify into this field more than 10 years ago, has transformed an innovative approach into economic success, shared by the 200 farmers in its production hinterland.

The first bioeconomy prize awarded in 2019 by the Ministry of Agriculture to Cavac Biomatériaux is not a cosmetic award for this SME of 45 people. It recognizes and rewards both its bio-based insulation solutions and a high performing organization based on short production cycles, strong management control and a zero-waste policy. It also shines a light on the unique history of Cavac, an agricultural cooperative firmly established in Vendée, which had the intuition in 2007 to foresee a future market in materials made from hemp.

A unique factory in Europe

Naturally resistant, promoting crop rotation, renewable and CO2 neutral, hemp is an advantageous plant in every way, even in its many non-food applications. Starting from this resource, Cavac has mobilized the cooperative members in its territory around an ambitious project designed to expand their activities and provide them with additional income. “Their desire was not to be simple producers of raw materials but to build a complete local value chain sector, from the field to the construction site, that is to say from production to distribution, by targeting in particular that construction requiring an increasingly local orientation ”, explains Valentin Colson, R&D Manager for Cavac Biomatériaux.

The concept evolved over two years and materialized in 2009 with the creation of the Cavac Biomatériaux subsidiary and through heavy investments in specific agricultural equipment and the construction of a straw processing plant. Unique in Europe, it integrates on the same 2,500 m2 site a defibration line which separates the straw constituents (hemp and oilseed flax) and a topping line which prepares the hemp fibers for use in flexible insulation panels. Cavac Biomatériaux launched its Biofib’isolation brand in 2010.

Comparable performance

First battles, first victories: obtaining certifications (ACERMI, technical opinions) which provide the insurability of products used in the building sector. From these little acorns and modest beginnings, the company R&D center is rolling out its innovation strategy and launching hemp-based products (100% or blended), and in particular Biofib’trio,made up of hemp, flax and cotton, which became and remains a bestseller. Between 2014 and 2019, the production of flexible insulation has tripled. First supporters of Biofib’isolation: the artisans. “Our products have aroused the enthusiasm of drywallers who appreciate the comfort they provide during installation: no gloves, no mask or risk of irritation. “By bringing them together from 2015 in a club (Biofib’Experts), Cavac Biomatériaux maintains their natural power as brand ambassadors.

The solutions that the company has introduced to the market also owe their success to the intrinsic properties of technical fibers. “Their earlier perceived technical weakness is no longer seen as a valid argument,” says Valentin Colson. Their performance, particularly thermal and acoustic, is very close to that of conventional products and meets the most stringent construction requirements. This is why these insulators are of increasing interest and see their scope of application being extended to high density housing projects as well as to public buildings such as schools.”

RE 2020, an asset

The R&D insulation activity of Cavac Biomatériaux remains directed towards the development of ever more efficient solutions but also on the demonstration of the product suitability for use as construction materials, vis-à-vis water/fire resistance, etc.  While Valentin Colson hopes that biobased materials will continue to take market share over polyurethane, polystyrene, glass wool and rock wool, he advises perspective: “We must, rather than doing without conventional products, select the right products for the right applications while always favouring materials with the lowest environmental impact. This is our vision.” Beyond its own success story, Cavac Biomatériaux, which is a member of IAR, a bioeconomy cluster, wishes to help promote wider recognition of the virtues of hemp in construction and to develop the sector in France. The entry into force in 2021 of the new Environmental Regulation RE 2020 should be beneficial for its further development.

Cavac Biomatériaux: a diverse product range

Technical hemp fibers, mainly for insulation application but also used  in the automotive and specialty paper sectors, represent 20 to 25% of the volumes produced by Cavac Biomatériaux; chènevotte (animal litter, mulching, hemp concrete) 55 to 60%; and fines (insulating screed) 15 to 20%.

Other fibers with insulating power

Apart from hemp, other natural raw materials are valued in the insulation market by members of IAR. SOPREMA, one of the world leaders in building insulation, provides solutions based on cellulose wadding and transforms (via its subsidiary Patavex) wood fibers. As for the Swiss Gramitherm process, it enables the manufacture of insulating panels made from grassland meadows from polders in Flanders and the Netherlands.



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