technical specifications
Thermal conductivity
Heat transfer coefficient U
Soundproofing
Binder fibers
Specific heat capacity c
Vapor diffusion resistance μ
Moisture behavior
Dimensional stability
Resistance against fungal attack (DIN IEC 68-2-10)
Fire behaviour (EN 13501-1)
λ 0,034-0,038 W/m,K.
0,226 W/m2,K (Layer Thickness 15 cm)
High sound absorption over a wide frequency range
synthetic or derived from starch
1.6 – 2.1 kJ/kg,K.
1-2 (open to diffusion)
Absorbs and desorbs moisture
(EU-Norm 1604) Dimensional variance max. +/-1%
No growth
Category E
facts and figures
quick facts
Heat Insulation
The measured thermal conductivity λ of Grass Insulation is between 0,034-0,038 W/m,K. With consideration of a safety margin, the European Technical Approval for Grass Insulation declares a thermal conductivity of 0,040 W/m,K. This figure is valid for a product density between 30-80 kg/m3. The thermal conductivity of Grass Insulation shows relatively little response to changing ambient air humidity, which is an advantage.
The U-value relates to the heat flow passing through a construction element of 1 m2 within 1 hour, at a temperature difference across this element of 1°K. At a thermal conductivity of 0,034 W/m,K and a thickness of 15 cm, Grass Insulation has a U-value of 0,226 W/m2,K. Proper accounting of all wall elements will further reduce (improve) this U-value.
Summer heat protection
The summer heat protection properties of insulation materials are of increasing importance, because the energy consumption of room climatisation is going up and requires expensive electric power.
These properties are described by the specific heat capacity c of a material. c is the amount of heat required to heat 1 kg of the material by 1°K. Renewable insulation product have a c-value between 1,6-2,1 kJ/kg,K. This value is clearly better then the respective values of mineral wool (c=0,8), which can be heated easier and provide limited protection against heat.
The insulation properties of a material result in a very slow transfer of heat through the material. The combination of thermal conductivity and specific heat capacity reduces the day/night temperature difference under the roof and releases heat during the night. Insulation materials from renewable materials exhibit an almost perfect delay of heat release of around 11 hours after heat uptake.
Moisture absorption and release
Cellulose has the capacity to absorb moisture from the ambient air and release it, when the ambient air becomes drier. This characteristic has a balancing effect on the room climate, which is generally considered as one of the advantages of renewable insulation materials such as Grass Insulation. They have varying moisture content between 5-11% of their weight. The board stability and life time are not affected.
Mineral insulation products do not absorb moisture, which can result in condensation of ambient air humidity at the dew point in the material and run-off of condensate in the material.
Vapour diffusion resistance
The vapour diffusion coefficient µ describes the resistance of a material to vapour diffusion. µ is a comparative value, that states how much stronger the resistance of the material is compared to the resistance of a layer of air of the same thickness. Air has a vapour diffusion coefficient of 1. Grass Insulation is open to vapour diffusion (µ=1-2). This is an advantage, because it prevents build-up of condensate on the warmer side of the material.
Resistance against fungi
The resistance of Grass Insulation against fungal attack was assessed according to the relevant EU norm. In this test, the material is exposed to fungal spores for 4 weeks at 23°C and moisture saturated conditions. Afterwards, the material is examined for fungal mycelia under the microscope.
Grass Insulation exhibited resistance against fungal attack (no growth). This resistance is due to its treatment with boric acid and borate.
Dimensional stability
The dimensional stability of Grass Insulation was tested according EU-norm 1604. The changes in the product length and width are around 0,3%. Grass Insulation does not expand or shrink when exposed to heat or moisture.
Green house gases / CO2-balance
The production energy requirement results in the emission of green house gases (0,4-0,6 kg CO2-equivalent per kg of Grass Insulation). However, grass takes up CO2 during its growth, just like all vegetable plants do. Per kg Grass Insulation, around 1320 g of CO2 are taken up and removed from the atmosphere. In summary, production of Grass Insulation is a net CO2 sink. Additional significant CO2-savings are related to the savings of heating energy during the life time of Grass Insulation.
Production energy input
The net energy requirement for production of Grass Insulation is 8-12 MJ per kg, depending on the production concept (renewable energy or animal feed as co-product). This figure includes raw material production and supply, the production of the additives, and the energy demand of the production process. For comparison: The respective values of polystyrene are almost 10 x higher.
Sound insulation
Grass Insulation exhibits excellent sound absorption capacity over a wide frequency range. An extension of the existing European Technical Approval of Grass Insulation to include sound insulation is expected until production start.
The production energy requirements can be 10 times less than polystyrene (oil) based insulation.
Unlike other insulation products, ours can be handled comfortably and does not cause skin irritation.
Summer heat protection is of increasing importance. By absorbing external heat during the day and releasing at night, Grass Insulation exhibits an almost perfect delay of its heat release, up to 11 hours after heat uptake.
Other insulators are unable to prevent the build up of condensation. Grass Insulation is open to vapour diffusion (µ=1-2) and prevents build-up of condensation on the warmer side of the material.
Grass Insulation absorbs ambient moisture and releases once the ambient air becomes drier. Unlike mineral insulation which can not, resulting in condensation.
The dimensional stability of Grass Insulation was tested according EU-norm 1604. The changes in the product length and width are around 0.3%. It does not expand or shrink when exposed to heat or moisture.
Grass Insulation exhibits excellent resistance against fungal attack as assessed according to the relevant EU norm.
Grass Insulation meets the criteria of the fire resistance class E according to the norm EN 13501-1. In the event of a fire the insulation does not produce harmful emissions.
In the event of water damage, Grass Insulation will soak water. With sufficient aeration it will dry and regain its full insulation properties.
Grass Insulation exhibits, not only, outstanding heat insulation but also excellent sound absorption over a wide frequency range. Therefore it is ideal for environments where both need to be taken into consideration.
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