NATURAL · BIO-BASED INSULATION
Thermo-Hanf Combi-Jute hemp insulation: summer comfort and stored carbon
Flexible batt made of hemp and recycled jute fibres, manufactured in Germany. A bio-based insulation that protects against summer heat, regulates humidity and stores CO₂ for the whole life of the building. Advice, supply and airtightness testing by Exp'Air 67 in Alsace and the Grand Est region.
Why choose Thermo-Hanf Combi-Jute?
A long thermal phase shift
With a specific heat capacity of 2,300 J/(kg·K), more than twice that of mineral wool (about 1,000), hemp slows down the passage of heat. At 200 mm, the insulation alone delays the heat peak by about 7 hours, compared with roughly 3 hours for a light glass wool of the same thickness (indicative estimate). The afternoon heat reaches the room at night, when you can ventilate.
High CO₂ absorption
Hemp grows in a single season, without chemical fertilisers or pesticides. One hectare of hemp captures about 14.5 tonnes of CO₂ per year, more than a forest on the same area. This carbon stays stored in the insulation: a direct advantage for the carbon indicator (Ic construction) of the French RE2020 regulation.
An efficient lambda value
Declared thermal conductivity λ = 0.038 W/(m·K) (manufacturer's technical data sheet 2026), on a par with almost all plant-based insulation materials. Thicknesses from 30 to 220 mm, laid in one or two layers to reach the thermal resistance required in new build and renovation.
Regulates humidity
Highly vapour-open (µ = 1 to 2), hemp absorbs and releases moisture without losing its properties. It is naturally resistant to mould (class 0 according to EN ISO 846).
Acoustic comfort
Its fibrous structure absorbs airborne noise very well: up to sound absorption class A at 160 mm. Ideal for partitions, floors and sloping roofs.
Healthy and pleasant to install
Does not itch or prickle; a flexible batt that recovers its shape after compression, so it wedges easily between rafters or studs. It contains recycled jute from coffee and cocoa sacks.
Technical data
| Composition | 66% hemp, 22% jute, 8% support fibre (PET), 4% soda |
| Thermal conductivity λ | 0.038 W/(m·K) |
| Specific heat capacity c | 2,300 J/(kg·K) |
| Density | approx. 39 kg/m³ |
| Water vapour diffusion resistance µ | 1 to 2 |
| Reaction to fire | Euroclass E (EN 13501-1) |
| Sound absorption | up to αw = 1.00 (class A) at 160 mm |
| Thicknesses | 30 to 220 mm |
| Formats | 1,200 × 580 mm (timber frame), 1,200 × 625 mm (metal studs), 1,200 × 840 mm (large format) |
| Approval | European Technical Assessment ETA-05/0037 |
Thermal resistance and phase shift by thickness
| Thickness | Thermal resistance R | Phase shift of the insulation alone* |
|---|---|---|
| 100 mm | 2.63 m²·K/W | ≈ 3.5 h |
| 160 mm | 4.21 m²·K/W | ≈ 5.5 h |
| 200 mm | 5.26 m²·K/W | ≈ 7 h |
| 2 × 120 mm (240 mm) | 6.32 m²·K/W | ≈ 8.5 h |
* Indicative estimate calculated from the manufacturer's data (λ, density, specific heat capacity), for the insulation alone. The actual phase shift of a complete wall or roof (breather membrane, boards, lining) is generally higher. Technical data: Thermo-Hanf Combi-Jute technical data sheet 2026 and ETA-05/0037.
Where to use it?
- Insulation of sloping roofs between rafters
- Lofts and floors between joists
- Timber-frame walls and half-timbering
- Partitions on metal studs
- Internal wall insulation in renovation
- Suspended ceilings and acoustic linings
Natural insulation + airtightness: the winning combination
Even an excellent insulation loses much of its efficiency if air flows around it. With a vapour-open insulation such as hemp, the vapour control layer on the warm side must be perfectly continuous. That is our job: Exp'Air 67 carries out blower door testing and infrared thermography to check that the installed insulation delivers what it promises.
- Advice on thickness and vapour control layer
- Intermediate test before the walls are closed, to fix leaks
- Final RE2020 test with report within 24 to 48 h
Frequently asked questions
Does hemp insulate as well as mineral wool?
In winter, at equal thickness, performance is similar (λ 0.038 compared with 0.032 to 0.040 for common wools). In summer, hemp does much better thanks to its specific heat capacity, which is twice as high: heat takes longer to pass through the wall.
What is thermal phase shift?
It is the time the outdoor heat peak takes to reach the inside. With a phase shift of 8 to 10 hours for the complete wall, the 3 pm heat arrives around midnight, when you can air the room. It is the key criterion for converted lofts that stay cool in summer.
Is bio-based insulation rewarded by RE2020?
Yes. The French RE2020 regulation calculates the carbon impact of materials over their whole life cycle. The carbon captured by the plant as it grows and stored in the insulation improves the project's Ic construction indicator.
Is hemp sensitive to moisture?
It naturally regulates humidity and resists mould. As with any insulation, the wall build-up (vapour control layer, breather membrane) must be carefully designed: we can advise you.
A natural insulation project?
2 locations in the Bas-Rhin to serve you better. Advice, price and availability within 24 working hours.