Table of contents:

Ecological insulation materials: the most important information
Ecological insulation materials: the most important information

Video: Ecological insulation materials: the most important information

Отличия серверных жестких дисков от десктопных
Video: The Different Types of Insulation | Fuel Poverty 2023, January

Ecological insulation materials are very popular with building owners and renovators who want to insulate their house well and thus contribute to climate protection. No wonder, they improve the indoor climate, are largely produced sustainably and can be recycled. We present you the most common natural insulation materials in a comparison and show advantages and disadvantages.

Table of Contents Table of Contents Ecological Insulation Materials: Information on Jute, Seagrass, Straw & Co.

  • Ecological insulation materials
  • Comparison of the most important sustainable insulation materials
  • Insulation obligation for conversion and extension
  • Ecological insulation materials: better for external or internal insulation?
  • Insulate with wood fibers
  • Insulate with jute
  • Insulate with sheep's wool
  • Insulate with sea grass
  • Insulate with straw

Table of Contents Table of Contents Ecological Insulation Materials: Information on Jute, Seagrass, Straw & Co.

  • Ecological insulation materials
  • Comparison of the most important sustainable insulation materials
  • Insulation obligation for conversion and extension
  • Ecological insulation materials: better for external or internal insulation?
  • Insulate with wood fibers
  • Insulate with jute
  • Insulate with sheep's wool
  • Insulate with sea grass
  • Insulate with straw

Poorly insulated old building walls, ceilings and roofs unnecessarily dissipate expensive heating energy. An insulation jacket around the house reduces heat loss by around 20 percent. Anyone who wants to protect the environment in addition to climate protection relies on ecological insulation materials made from natural materials and sustainable production.

Ecological insulation materials

Compared to conventional insulation materials for thermal insulation, natural insulation materials regulate the room climate better, so that the residents feel comfortable and comfortable in their rooms. On the one hand, their moisture behavior is above average: they transport moisture and are able to temporarily bind it. On the other hand, in summer they reduce and delay the heat input into the house.

Sustainable insulation is usually free of pollutants. This applies to the manufacturing phase, the time of its use as insulation and its disposal. It should also be reusable and easy to dispose of at the end of its life cycle without harming nature. For example, some natural insulation materials can be composted. Many natural insulation materials also come from local agriculture and forestry, thereby boosting the regional economy.

But be careful: The term "eco" should not hide the fact that some insulation materials made from natural materials can contain additives to improve their technical properties that are in no way ecological. If, for example, boron salt or boric acid is included as fire protection, these insulating materials must not be composted under any circumstances. Natural insulation materials that are flammable and do not contain these additives are currently not permitted. However, the admission requirements change again and again. Such additives can be added to new products.

Thermal conductivity and heat transfer coefficient

The thermal conductivity and the heat transfer coefficient (U-value) determine the amount of heat transport through a component and are therefore the most important values ​​of an insulation material. Any material with a thermal conductivity (lambda value) of less than 0.1 W / mK counts as such - the value explains how well the insulation material transports heat. The lower the value, the better the material is insulated. Resting air conducts heat poorly, which is why a material insulates the more effectively the more porous it is.

The heat transfer coefficient indicates how much heat flows through a square meter of material per time. The Energy Saving Ordinance EnEV 2014/2016 prescribes a U-value of 0.28 W / qmK for "outside walls against outside air".

Ökologisch dämmen mit Hanf
Ökologisch dämmen mit Hanf

A thermal insulation concept with hemp is one of the most effective and ecological ways to build an efficiency house.

Photo: iStock / Francesco Scatena

Comparison of the most important sustainable insulation materials

The following criteria play an important role in our comparison of ecological insulation materials: thermal conductivity, fire protection class and vapor diffusion ability. From an ecological perspective, the primary energy requirement must also be taken into account. It describes the amount of energy that is required to manufacture the insulation material. It is not always possible to calculate this exactly, but at least a division into “low”, “medium” and “high” is possible. Furthermore, the possible emission of pollutants and the recyclability or disposal are important criteria. We also found big differences in costs. For all properties, you will find information below for these insulation materials:

  • cotton
  • Expanded glass granules
  • Expanded clay
  • Flat
  • hemp
  • Wood shavings
  • Fiberboard
  • jute
  • Coconut fiber boards
  • cork
  • Sheep wool
  • reed
  • straw
  • Seagrass / Neptune balls
  • cellulose
Thermal conductivity











in the


disposal costs

(Euro / sqm)

cotton 0.04 B1, B2 1 - 2 low -




recyclable 15-18
Expanded glass


0.065 - 0.070 A1 3-4 not specified No recyclable, landfillable 18-20
Expanded clay 0.080 - 0.180 A1 5 - 10 high No recyclable, landfillable 60-90
flax 0.036 - 0.040 B2 1 - 2 low No recyclable, compostable 35
hemp 0.048 B2 1 - 2 low No recyclable, compostable 10-27
Wood shavings 0.045 - 0.075 B2 2nd low No recyclable not specified
Wood fiber


0.040 - 0.052 B2 2 - 5 medium possible recyclable, compostable 40-65
jute 0.037 - 0.040 B2 1-2 low No recyclable, compostable 10 - 30
Coconut fiber


0.045 B2 1 low possible recyclable, compostable 20-23
cork 0.04 B2 5 - 10 high possible landfillable 20-75
Sheep wool 0.037 - 0.040 B2 1 - 2 medium -


more controversial

Moth protection

recyclable 40-60
reed 0.055 - 0.065 B2 3 - 6.5 very low No recyclable 10-20
straw 0.052 B2 2nd very low No recyclable 10-15
Seagrass /

Neptune balls

0.039 - 0.046 B2 1 - 2 very low No recyclable 25-43


0.042 B2 2-3 low Borax, Boric acid, Aluminum-

hydroxide, Ammonium-

phosphate, Fungotannin

recyclable, not compostable 35-45

Insulation obligation for conversion and extension

Good insulation is now mandatory in new buildings, but old buildings should also reduce their energy consumption. Energy-saving measures such as thermal insulation are mandatory according to the Energy Saving Ordinance (EnEV) if you:

  • comprehensively modernized, i.e. more than 20 percent of the components
  • adds more than 30 cubic meters of additional space
  • extends the storage to living space
  • covers more than a fifth of an inhabited roof

In all these cases, the EnEV specifies the maximum heat loss through the basement and roof, walls, ceilings and windows.

Good to know: For one- and two-family houses in which the owner lives, the retrofitting requirement only applies if the owner changes. If nothing changes in the ownership structure, dams are voluntary - with the exceptions mentioned above.

Ecological insulation materials: better for external or internal insulation?

Natural insulation materials can be applied from the outside, in the core of a double-walled wall or from the inside. With the same insulation thickness, external and internal insulation brake heat losses equally well. In terms of building physics, however, external insulation is more advantageous.

  • Thermal bridges, the main control centers for energy losses, can be avoided better with external insulation than with internal insulation.
  • The external insulation takes up less living space.
  • Water vapor can migrate through the wall without causing damage - if all layers are open to diffusion.

Good to know: Most ecological insulation materials cannot be used as perimeter insulation (i.e. on components that come into contact with the ground or are at risk of splashing water).

Sustainable insulation materials can also be applied inside, for example if the appeal of a valuable old building facade is to be preserved. Listed houses or particularly pretty facades, stucco and half-timbering cannot be hidden behind thermal insulation - that is forbidden by itself. The interior insulation preserves valuable facades and decorative details remain visible. However, it is important to avoid the following problems:

  • Thermal bridges: Wherever ceilings and partitions protrude into the outer wall, thermal bridges almost always arise. They are colder than the rest of the wall and are therefore often damp and moldy. Such places have to be improved separately.
  • Risk of frost: The temperature gradient of insulated walls changes - less heat flows outside, frost penetrates deeper into the wall.
  • Relocation of the dew point: water vapor from the room air penetrates into walls and liquefies - where this happens is the so-called dew point. Steam only thaws outside on cleverly constructed walls. Improper internal insulation shifts the dew point into the wall and moistens it over time. So you have to prevent the steam from migrating and attach a vapor barrier in front of the interior insulation or buffer the condensate in a planking.
WDVS Holzfaserdämmplatte
WDVS Holzfaserdämmplatte

ETICS are available in different materials: The wood fiber insulation board is glued to the wall with a mineral adhesive mortar.

Photo: Steico / Quick-Mix

Natural insulation made from wood fibers

Wood is one of the renewable raw materials that can also be used in ecological building. Wood fibers are most often used as ecological insulation material and accordingly have the largest product range. The right shape is available for every location, from slabs and mats to blow-in insulation. Insulation materials made from wood fibers are therefore used as insulation, under-rafters, impact sound insulation for the floor, suspended ceiling, plaster base, acoustic ceiling or also in the ETICS.

  • pollution-free production
  • no foreign binders
  • Leftover building materials and removed panels can be recycled
  • enable high quality sound insulation
  • high sorption capacity: fibreboard absorbs room moisture and releases it again when required
  • comparatively high price
  • normally flammable, not non-flammable
  • Insulating effect is not outstanding, rather an upper mediocrity
  • difficult to process because it can only be cut with a special tool
  • Fine dust pollution during processing requires respiratory masks and suction devices

Ecological insulation material jute

As an ecological insulation material, jute is best compared to flax and hemp. While these are produced in Germany, jute comes from Africa and covers another route. However, the insulation material is obtained from disposed coffee bags that are already in Germany and would otherwise be burned. So it is already the second life cycle of the material.

  • Jute insulation is an upcycling product
  • Material can be cut and fitted very well, and in some cases it is even delivered as measured
  • can also be used as a stuffing material for sealing windows and doors
  • unusually good heat protection
  • resistant to mold
  • uninteresting for insects and rodents
  • no risk to health
  • biodegradable
  • cheaper than insulation materials with comparable good insulation values
  • Insulates less well than conventional insulation materials such as polystyrene, so a thicker layer of insulation is required
  • more expensive than conventional insulation materials
  • Possible smell
  • normally flammable, not non-flammable

The ecological insulation material jute is made from used jute sacks and is therefore an upcycling product.

Photo: iStock / eyewave

Sustainable insulation wool

Sheep wool can look back on a long historical tradition as an insulating material because it has excellent soundproofing and thermal insulation properties. That is why it was previously often used in industry, for insulating large cooling systems or noisy machines. The ecological insulation material sheep wool has a high degree of moisture regulation and even breaks down pollutants in the air - which makes them particularly interesting for low-pollution construction.

  • renewable by-product of animal husbandry and pasture farming
  • Raw material is not subject to natural aging, therefore extremely long shelf life
  • far greater elasticity than conventional insulation, making it particularly dimensionally stable
  • excellent noise and heat protection
  • permeable and capillary active
  • odor and pollutant neutralizing
  • resistant to moisture, mold and decomposition
  • Controversial borates or other chemical additives are added to protect moths. So far, only Ionic Protect® is biocide-free
  • Withstands heavy pressure loads comparatively poorly
  • normally flammable, not non-flammable
Schafwolle als Dämmstoff
Schafwolle als Dämmstoff

From shaving to use as an ecological insulation material, sheep's wool goes through a number of complex manufacturing processes.

Photo: iStock / ideeone

Ecological insulation made from sea grass

Seagrass fibers for insulation are obtained from the so-called Neptune balls, which can be collected on Mediterranean beaches. They consist of clumped remains of seaweed leaves that are formed into spheres by the wave motion on the beach. In simple mechanical processes, they are crushed and screened until a homogeneous wool is created. The transport routes alone allow the primary energy content to be higher compared to other natural insulation materials - albeit still significantly lower than with conventional insulation materials. The seagrass insulation material is introduced by pouring, plugging or blowing in, for example to insulate a floor or wooden beam ceiling, as blow-in insulation in roof and facade renovation.

  • resistant to fungi, pests and putrefaction
  • very good moisture regulation
  • open to diffusion
  • very good heat protection
  • not flammable
  • limited pressure load
  • long transport routes
  • not yet available as insulation mats

The balls of sea grass - also known as "Neptune balls" - are washed up on Mediterranean beaches and processed into a homogeneous, ecological insulation material.


Natural insulation straw

Since the 1970s, the temporarily displaced natural straw insulation material has been making a comeback. Because it is practically on the doorstep: threshed straw provides excellent insulation without additional manufacturing or energy expenditure. For this, the building straw bales with the required density are already pressed on the field. Then they are used as an insulating infill in the timber frame construction or in the framework renovation. As special, high-density straw building boards, the ecological insulation material is also used as internal insulation.

  • Excellent U-value, therefore suitable for the construction of a passive house
  • Regional, available without complex manufacturing processes
  • Open to diffusion, moisture regulating
  • Reusable or compostable
  • Flammability drops with a clay plaster
  • Very cheap, direct purchase from farms
  • Straw bales must be protected from moisture with suitable wood-based panels and other cladding, otherwise they will be modern and moldy
  • Therefore not approved as core insulation for double-layer masonry
  • Require thicker layer of insulation
  • Load-bearing straw insulation must be approved separately by the building inspector
  • Limited pest protection (only with insect screens for the ventilation level and quick plastering of the building)
Ökologische Strohdämmung
Ökologische Strohdämmung

Straw is a natural and ecological insulation material and has good thermal insulation properties.

Photo: iStock / Andreas_Krone Eva Bolta Redaktion

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