Natural insulation

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Thermal insulation of a house roof with wood fiber insulation panels combined with insulation made from cellulose.

The term natural insulation materials are insulation materials from materials of vegetable, animal and mineral origin summarized.


Natural insulation materials are made on the basis of various crops such as flax fiber (flax fiber), grain , hemp , seagrass, wood , jute , cork , reed , sisal fiber , coconut and meadow grass . In addition, wool and minerals such as perlite , vermiculite and calcium silicate used as insulation. Insulation materials made from recycled material are sometimes also referred to as natural insulation materials, provided they consist of biogenic raw materials (e.g. cellulose fibers from waste paper , foam glass gravel from recycled glass ).

To protect against pest and mold infestation and for fire protection, all organic natural insulation materials are usually injected with small amounts of protective substances, such as whey , boron salts , soda or cement in the case of wood shavings or wood wool lightweight boards , via aluminum sulphate , paraffin or ammonium sulphate in wood fiber insulation boards , with the exception of seaweed, which is naturally resistant to mold, fire (B2) and vermin. This is not necessary with mineral insulation and it is also non-flammable (A1). Most of the additives used are harmless during production and use, in some cases (for example synthetic fiber components in natural fiber mats) these additives hinder chemical or biological degradability during disposal . In order to improve the processing and to increase the dimensional stability, synthetic polyester fibers are also used as support fibers in some natural insulation materials . Alternatively, coconut fibers , potato starch or water glass are used.


Insulating effect

The thermal insulation effect of natural insulation materials corresponds to that of conventional mineral and fossil insulation materials ( thermal conductivity group 035 to 055).

In the field of high-performance insulation materials , vacuum insulation panels made of polymer-soaked cellulose honeycomb panels are being developed, which are at least partially made from renewable raw materials. Most natural insulation materials (especially wood fiber insulation materials) have a significantly higher level of thermal insulation in summer than conventional fossil and mineral materials, so the insulated rooms remain cooler during the day even when the outside temperature is high.

Moisture absorption

In contrast to the other insulation materials, most natural insulation materials are sorbent , they can absorb and release moisture without losing the insulation effect. Short to medium-term effects of moisture are in many cases problem-free and can then dry off again, so that the risk of mold formation is also reduced. Permanent moisture damages organic natural insulation materials.

Other properties

The common natural building materials are classified either as normally flammable or as hardly flammable. The soundproofing effect differs considerably between the insulation materials, and have good soundproofing properties. a. Insulation materials made from seaweed, coconut fibers, cellulose or wood fibers.

Standards and approvals

Relevant DIN standards exist primarily for a range of insulation materials based on wood products (wood wool lightweight board, soft wood fiber board, wood fiber board with resin), but also for coconut fibers and cork . Insulation materials that are not subject to DIN can receive a building inspection approval from the German Institute for Building Technology . Another form of quality assurance are certificates of conformity. These are issued by certification and monitoring bodies and confirm compliance with legal requirements. Non-approved insulation materials can be approved on a case-by-case basis.

Areas of application

Natural insulation materials can be used for all indoor applications. Sound and thermal insulation for walls, ceilings, floors and roof insulation. Outside, behind cladding, as a fill and as a thermal insulation composite system . Natural insulation materials made from renewable raw materials, cellulose and sheep's wool are not suitable for use in components that are at risk of splashing water and areas in contact with the ground ( perimeter insulation ). An exception is the insulation of expanded and foam glass (recycling from waste glass), which is also approved for perimeter insulation.

Sales and market

In Germany, sales of insulating materials made from renewable raw materials are increasing. The market share of insulating materials made from renewable raw materials was 5% in 2005. Soft wood fiber insulation boards (in 2006 28% of the natural insulation market), blown cellulose (32%), other lightweight boards (20%), flax and hemp insulation (9%) and insulation made from sheep's wool (4%) are used.

Types of natural insulation

Flexible wood fiber insulation
Wood wool lightweight panel as a window reveal
Cellulose flakes are introduced via the dispenser (barrel) and blown into cavities through the hose.
Insulation block made of hemp fibers
Wall model with seagrass insulation

Wood fiber

Wood fiber boards consist of coniferous wood residues, which - with two different processes - are treated and shredded and provided with additives. Wood fiber insulation boards as a permanent and strong insulating fiber composite without external binders are offered in various designs (including firm and flexible) and can be used universally. The square meter costs are slightly higher, but with very good summer heat protection and good workability (similar to wooden panels and can also be processed by yourself). Loose wood fibers are also used as blow-in insulation . Wood fiber boards are well suited to create a vapor-permeable cavity in which other natural insulation materials, such as. B. seaweed, can be filled in loosely.

Wood shavings to be blown in

Wood shavings from the wood processing industry with additives against pest infestation and mold as well as fire protection are used as blow-in insulation . The insulation layer is open to vapor diffusion and compensates for moisture. The sound insulation properties and summer heat protection are high. Wood shavings are mainly used for insulation between rafters, in timber frame construction and in timber panel construction.

Wood wool lightweight panels

Wood wool lightweight panels (HWL panels) have been standardized as insulation materials since 1938 . The dimensionally stable and very solid components consist of wood wool, which are pressed into a mold with cement or magnesite as a binding agent and then harden. The panels are resistant to rot, fungi and animal pests; additionally fire-retardant and moisture-absorbing. They are mainly used as a plaster base - also outdoors, as well as for the insulation of highly thermally conductive components in masonry and concrete construction and as planking in timber construction. With a thermal conductivity of 0.090 W / (m · K), their thermal insulation effect is only about half as high as that of other natural insulation materials. Special products optimize the insulating effect by inserting more effective insulating materials between two wood wool lightweight panels. Unplastered, the panels absorb sound; as plastered components, they have a sound-absorbing effect. Therefore, wood wool lightweight panels are also used as acoustic panels. These can also be optimized with special surface profiles for sound insulation. The manufacture, use and disposal of the panels are considered to be harmless to health, the insulation material is recyclable and can be used thermally.


Cellulose from waste paper is frayed in mills ( e.g. eddy current mills ) and mixed with various additives. The loose flakes are blown into cavities in the roof, wall and ceiling area, applied as loose fill or sprayed on wet. When pressed, cellulose with polyolefin plastic fibers is used as a very elastic and dimensionally stable cellulose insulation board. Cellulose has good thermal insulation and storage properties. Fire protection: Euroclass according to EN 13501-1: E, recyclable and has a high level of moisture resistance with the same insulating effect. Cellulose is not permitted for core insulation , where permanent moisture exposure is possible. As a pure recycling material, injected cellulose insulation requires the lowest primary energy input of all insulation materials (55–70 kWh / m 3 ) and is one of the cheapest.

Flax and hemp

Hemp and flax fibers are processed to insulating mats that obtained in the hemp fiber production as a coproduct shives be used mixed with bitumen and clay granulate as bulk insulating materials or they can be pressed into solid plates. The insulation mats are used in walls, roofs and floors. The pleasant processing (skin-friendly, low-dust) using synthetic polyester fibers as support fibers is interesting. Above all, the insulation products with hemp shives offer not only a heat insulating effect but also a high level of sound insulation.


The seaweed of the Baltic Sea ( Zostera marina ) and the so-called sea ​​balls with Neptune grass ( Posidonia oceanica ) from the Mediterranean are also used for insulation. What they have in common, among other things, is that they have a particularly good ecological balance because the sea throws them onto the beach like a waste product. They do not require any special preparation.

Pure mineral natural insulation materials

Even purely mineral insulation materials without additives such as B. Polystrol are natural insulation materials.

Other natural insulation materials

Rye meal can be used in granulate form as bulk insulation, inflation or inflation insulation. Sheep wool mats, straw mats, straw bales , cork sheets or granulated cork, reed sheets , coconut fibers and mats are examples of natural insulation materials that are used in niche markets or in special areas of application.

Environmental aspects

Compared to mineral or synthetic insulation materials, the environmental impact of natural insulation materials is generally much lower, both during production, during use and during disposal. Instead of limited fossil or mineral raw materials, renewable raw materials are used. Since the pollution of natural insulation materials is usually very low, they are classified as beneficial in terms of building biology . Due to the natural material basis, natural insulation materials do not cause any disposal problems after use, many are biodegradable .

The energy used in the production and thus the emission of climate-relevant gases is several to many times lower than that of other insulation materials. With regard to the energy and climate balance, in addition to the energy consumption of the insulating materials during manufacture, application and disposal, the saving of energy (e.g. heating energy) through the use of the insulating materials plays an important role. Since in the overall energy balance the energy consumption of the production is offset by the saved heating energy after a few weeks or months of use, the insulation effect achieved is decisive for the overall balance. With structurally limited insulation thicknesses, the use of synthetic or mineral high-performance insulation materials with a particularly high insulation effect (e.g. panel insulation materials up to thermal conductivity group 023, vacuum insulation panels up to 0.004) can be more energetically positive than the use of natural insulation materials. Wherever sufficient insulation thicknesses are possible, natural insulation materials have a clear advantage.


  • aid e. V., 2005: Building on the power of nature. Building materials made from renewable raw materials. ISBN 3830805438
  • Bruckner / Schneider: Naturbaustoffe Werner Verlag, Düsseldorf 1998, ISBN 3-8041-4140-4

Web links

Individual evidence

  1. .
  2. Michael Carus et al .: Study on the market and competitive situation for natural fibers and natural fiber materials (Germany and EU). Gülzower Expert Discussions Volume 26, Fachagentur Nachwachsende Rohstoffe eV 2008, p. 180 f.
  3. Aachener Zeitung, dpa: Insulating the house with seaweed , March 13, 2013.
  4. Holznagel magazine of the IG Bauernhaus: Seegras - the ideal insulation material for old houses , February 2013.