By far the greenest of the eco friendly insulation materials. It is what it says on the packing – 100% natural sheep wool. Its K-value is 0.039, which is better than all the mineral-based synthetic materials (mineral wool is 0.042). There is minimal grey energy involved in producing sheep wool insulation – I mean, how much CO2 do you emit shearing a sheep? It also complies with the current fire safety standards.
Untreated wool is naturally fire-detergent because it is “dirty”. A sheep is a rather fire-proof animal. However, many of the modern sheep wool insulation materials are treated with salts for even higher fire detergent characteristics. Wool, unlike other insulation materials, is hygroscopic, i.e. it can absorb water. Dampness is mineral wool’s biggest enemy – it reduces its efficiency. Sheep wool? It doesn’t care about dampness. Wet wool is as good an insulator as dry one.