Sustainable beech-wood fiber insulation materials as flexible insulation mats and for the filling of thermal-insulation bricks for the construction industry

Beech-wood insulation – Project start / October 01, 2022

Flexible wood-fiber mats are ideally suited for the thermal insulation of buildings - for example as between-rafter insulation or as a filling material for thermal-insulation bricks. Until now, wood-fiber insulation materials have been manufactured primarily from softwood. As a result of climate change, this will be available in significantly smaller quantities in the future. In order to secure the raw-material base for wood-fiber insulation materials and to expand their application potential, we are working in collaboration with industrial partners on the development of insulation mats and novel wood-foam granules made from beech-wood fibers. The project objective is the establishment of a pilot plant for material production. In this way, we are creating a sustainable perspective for the construction industry as well as a high-quality utilization possibility for beech wood, which will be increasingly available in the future due to climate-related forest restructuring. In order to exploit the resource “beech wood” even more efficiently, it would also be conceivable to utilize the new wood-foam granules as a filler for transport packaging.

Last modified: October 01, 2022

The photo shows a commercially available, vertically positioned masonry brick with 12 evenly spaced cavities. The cavities are filled with a variety of fiber-mat types. In front of the brick is a large pile of brown beech-wood fibers and a small pile of white bico fibers. — © Fraunhofer WKI
Thermal-insulation bricks with a regular hole pattern and conventional insulation mats made from glass fibers (below), mineral fibers (above) and softwood fibers (center). The project team is developing a climate-friendly fiber mat made from beech-wood fibers (brown) and bico fibers (white) with flame retardancy.

The photo shows a masonry brick with numerous small, variously shaped cavities. — © Fraunhofer WKI | Manuela Lingnau
For the filling of thermal-insulation bricks with an irregular and very small-scale hole pattern (hole-pattern-independent), the project team is developing a suitable wood foam and wood-foam granules made from beech-wood fibers with flame retardancy.

Pulping processes and insulation production

In collaboration with our project partner Loick Biowertstoff GmbH, we are investigating which processes can be used to break down and further process beech wood into fibrous materials for the production of insulation mats and wood foam or wood-foam granules. Amongst other things, low-value damaged wood (calamity wood) is to be used for this purpose.

Fiber mats

In order to achieve the desired structure, strength and elasticity in the fiber mats, we want to adapt a commonly used manufacturing process for wood-fiber insulation materials, into which supporting fibers made from thermoplastic material are introduced. Bicomponent fibers (in short: “bico fibers”) are generally used for this purpose; these consist of a permanently elastic inner part and a hot-melt adhesive sheath. Our goals:

Minimization of the proportion of bico fibers, and testing of bio-based bico fibers
Optimization of the blending of the two very different fiber types (wood fibers and plastic fibers)
Optimization of the heating of the fibrous fleece / bonding between wood fibers and bico fibers, for example through:
- hot air
- hot vapor
- microwave or high-frequency excitation
Production of a flexible insulation mat made from beech fibers and bico fibers, which could be used analogously to the softwood insulation mats available up until now - for example for between-rafter insulation in roofs, compartment insulation in wooden construction and drywall construction, or the filling of hollow bricks.

Wood foam / wood-foam granules

For the production of wood foams, we employ a process developed at the Fraunhofer WKI. In order to produce wood-foam granules, the manufactured wood foams are subsequently broken down into granules using various crushing units and, if necessary, additionally hydrophobized. The goal is a pourable (solid or liquid) material that can be utilized in the insulation of buildings.

Flame protection

In order to achieve the building material class “normally flammable”, we will, if necessary, enhance the various beech-wood fiber insulation materials by means of flame retardants, which will be incorporated during the manufacturing process. The aim is for “highly fire-retardant” (60 min) or “fire-resistant” (90 min) walls to be constructed using the thermal-insulation bricks.

Procedure for the filling of hollow bricks

As a specific application example for the new beech insulation materials, we are testing the filling of hollow bricks (“thermal-insulation bricks”) in this project - in cooperation with the industrial partners Loick Biowertstoff and Ziegelwerk Bellenberg.

Bricks with large / regular hollow chambers (“hole-pattern-dependent”)

Insertion of the beech insulation material into the hollow chambers with the aid of filling machines currently used by the brick manufacturer Bellenberg for filling using mineral wool or glass wool
Technical adaptation of the plant, for example with regard to feeders, strengths and cutting tools

Bricks with small / irregular hollow chambers (“hole-pattern-independent”):

Filling of the hollow chambers with liquid or pourable insulation materials.

For both types of bricks, the adhesion between the brick surfaces and the insulation material is to be investigated and optimized. Objective: The insulation material should be “bonded” in the holes in such a way that no insulation material can escape when the bricks are cut or drilled.

Pilot plant for insulation production

In collaboration with the company Loick, we are developing and constructing a functional pilot plant for the production of insulation material made from beech wood.

In the development of an economically viable plant concept, we consider, amongst other things:

Selection of an optimal pulping process (dry or wet pulping)
Selection of a suitable pulping unit (refiner, ecopulser) for beech-wood fibers as the main component of the plant
Selection and design of plant components such as mixing units for wood and bico fibers, fiber-fleece laydown, and the drying system
Testing of possible methods for the filling of hole-pattern-independent bricks with wood-foam granules
Raw material and logistics costs, suitable logistics and storage concept

Recycling process / recyclability

In collaboration with the company Bellenberg, we are investigating the recyclability of the insulation-filled bricks. This includes:

Process development for the separation of bricks and insulation material
Tests on the reconditioning of the emptied bricks and their renewed utilization as thermal-insulation bricks
Tests on the reprocessing of wood-fiber insulation materials to create new insulation materials
Investigations into the utilization of broken bricks (e.g. as granulate for plants)

Evaluation of insulation material and component properties

During the course of the project, we will evaluate the beech-based insulation materials (mats, boards, foams and granulates) with regard to their physical-technological properties and their utilization in bricks and wall structures.

Insulation materials: determination and optimization of mechanical properties such as thickness, density and dynamic stiffness in accordance with current standards
Determination of the thermal conductivity of the brick with and without insulation filling
Water absorption and release of the filled brick (if necessary with hydrophobic insulation material)
Determination of the fire-resistance duration
- Testing of all developed beech-wood insulation materials for normal flammability before and after enhancement by means of flame retardants
- Determination and analysis of the gases produced in the event of fire
- Production and testing of a wall made from various perforated bricks with various insulation fillings (project partner: Bellenberg)

Life-cycle assessment

Parallel to the development of the insulation materials, Loick will determine the material and energy requirements for the production of the insulation materials. These will serve as the basis for assessing greenhouse-gas emissions - from the “cradle to the factory gate” (cradle-to-gate). In addition, possible climate impacts in the “end-of-life” phase (disposal of the insulation materials) or “second life” phase (renewed utilization of the insulation materials) will be considered. By means of contribution analyses, the greenhouse-gas-intensive process steps will be identified and optimization potentials derived.

In order to save heating energy in winter, buildings need a well-insulated outer shell. This simultaneously protects against heat in summer. Wood-fiber insulation materials are a sustainable possibility for insulating buildings against cold and heat. They have proven their worth for years - for example, in the form of mats for between-rafter insulation or cavity insulation in wood-panel construction. Because of their ecological advantages and good sound-insulating properties, wood-fiber insulation mats are also utilized in interior construction - for example in drywall structures or in wooden-beam ceilings.

Currently, only softwood is used in wood-fiber insulation production on an industrial scale. As a result of climate change, however, significantly less coniferous wood will be available in the future. Drought, storms and the climate-induced mass reproduction of insect pests lead to large-scale die-back - particularly in pure spruce stands. In order to reduce the risk of large-scale forest damage in the future, politicians and forest owners are increasingly focusing on near-natural mixed forests. In the future, more hardwood – such as beech – will therefore be available. Up until now, a large proportion of beech wood has been marketed as firewood.

With this project, we are securing the raw-material basis for wood-fiber insulation production. In addition, we are creating a possibility for using the increasingly accumulating beech wood in a high-quality manner and several times in succession (cascade utilization). As a result, we are providing a contribution towards a bio-based, climate- and resource-conserving circular economy (bio-economy).

In order to ensure the most efficient use of raw materials, we also consider the use of beech calamity wood: Although deciduous trees such as beech and oak can cope better than spruce as regards the altered climatic conditions, considerable damage can nevertheless be expected during severe drought - even in deciduous and mixed forests.

Furthermore, in this project we are expanding the application possibilities for wood-fiber insulation materials. In thermal-insulation bricks, they have so far only been incorporated in mat form - analogous to filling with glass wool or mineral wool. This limits the utilization of wood-fiber insulation materials to bricks with reasonably large, regularly shaped cavities. Thermal-insulation bricks with small and/or irregularly shaped cavities are currently filled with mineral granules such as perlite. With the planned wood-foam granules, we are developing for this purpose an alternative made from renewable raw materials.

External walls made from thermal-insulation bricks are an alternative to façade insulation with external thermal insulation composite systems (ETICS) and can, depending on the installation situation, offer a number of advantages:

Reduction of space requirements compared to a wall with façade insulation
Durability: insulation material lies in the brick, protected from weather and fire
Easy installation of exterior wall elements such as canopies
Easy replacement of windows and doors

For the utilization of wood-fiber-based insulation materials in the construction industry, the model building code requires that the building material must be at least normally flammable. In the higher building classes, flame-retardant building materials are required. Through the incorporation of flame retardants in the beech-wood fiber insulation materials, we ensure that the insulation materials produced with them can be used in as many types of buildings as possible.

It is furthermore conceivable for the new wood-foam granules to be used as a sustainable filling material in the packaging industry. This would be a further possible use for beech wood prior to thermal utilization (incineration).

Economic advantages

Upon successful completion of the project, an economically attractive solution for the production of wood-fiber insulation materials from beech wood will be available. This is an important step towards securing and broadening the raw-material base in view of the forest restructuring resulting from climate change.

Furthermore, the development of innovative wood-foam granules made from beech wood opens up new application possibilities in the field of filling materials for insulation solutions (e.g. thermal-insulation bricks) and packaging - with substantial recycling potential.

For the construction industry and the logistics sector, this broadens the room for maneuver as regards fulfilling the increasingly stringent sustainability requirements imposed by politics, business partners, B2B customers and end consumers. Diverse companies and facilities along the value chain could benefit from this, including:

Forestry operations and sawmills
Manufacturers of insulation materials, fillers, thermal-insulation bricks and packaging
Construction companies
Demolition and recycling companies
Commercial, public and private builders
Architecture and construction-planning offices
Property developers
Forwarding agencies and other transport companies
Mail-order companies

Overall, the project will strengthen the competitiveness of the bio-economy within Germany as well as the growth potential on international markets.

Project partners

Joint project coordination: Loick Biowertstoff GmbH
Fraunhofer WKI
Ziegelwerk Bellenberg Wiest GmbH & Co. KG

Funding

Official project title:
Verbundvorhaben: Aufbau einer Pilotanlage zur Nutzung und Evaluierung von Buchenholzfasern als Ziegel-Dämmstoff
(Joint project: Construction of a pilot plant for the utilization and evaluation of beech-wood fibers as brick insulation material)

Sub-project 1 (Loick Biowertstoff): Aufbau einer Pilotanlage
(Construction of a pilot plant)
Sub-project 2 (Fraunhofer WKI): Optimierung und Evaluierung von Buchenholzfaserdämmstoffen
(Optimization and evaluation of beech-wood fiber insulation materials)
Sub-project 3 (Ziegelwerk Bellenberg): Füllung von Ziegeln mit Holzfaserdämmstoffen
(Filling bricks with wood fiber insulation materials)

Funding body: German Federal Ministry of Food and Agriculture (BMEL)

Project management: Fachagentur Nachwachsende Rohstoffe e. V. (FNR)

Funding reference: 2221HV003A, 2221HV003B, 2221HV003C

Duration: 1.10.2022 to 30.9.2025