Building physics
of hemp limestones
The all-rounder for a balanced indoor climate
Thermal insulation
The Isohemp hemp block offers an insulating performance on a par with modern building materials. With a thermal conductivity λ of 0.071 W/(m·K), the hemp-lime block easily holds its own against competing products.
Because of its good insulating properties, hemp-limestone can be used for modern new buildings. A timber frame wall, infill with a 30 hemp-limestone, achieves an insulation value of 0.23 W/m²K. The current EnEV stipulates a U-value of 0.24 W/m²K for extensions to an existing building.
In new builds, a minimum thermal insulation of ~0.20 W/m²K is required for a KfW 55 house. This can be achieved with a 38 cm block plus a 24 mm wood fibre insulation board as the external finish.
In timber frame renovation, the hemp-limestone can be used very well for the interior insulation of an existing timber frame wall. 120 mm hemp-limestone provide a better insulation value than interior insulation with 160 mm light clay. Due to its moisture-regulating properties and the high pH value of the lime, which reduce the risk of mould, the hemp-limestone is well suited for historical building fabric.
Sound insulation, diffusion of sound
The inhomogeneous hemp fibre mixed with the mineral lime binder creates very high sound insulation. Thus, partition walls between two rooms can achieve a sound reduction of 57 dB.
For partition walls between two residential units, sound insulation can be further improved by a two-layer, decoupled construction.
Non-flammable, strongly alkaline
Hemp does not need any pesticides, fertilisers or much moisture in cultivation.
Hemp is a historical cultivated plant with the lowest demands on soil and nutrient supply.
By mixing it with lime, the resistant hemp fibre becomes an even more stable building material. This hemp limestone is not combustible!
As a fibre, hemp absorbs an extremely high amount of moisture without feeling wet at all and without losing its insulating effect. The moisture can be quickly released back into the room air. The high pH value of the lime and the moisture-regulating properties of the hemp-limestone reduce the risk of mould.
