| Wool is a natural insulator, it's called a hygroscopic fibre. As the humidity of the surrounding air rises and falls, the fibre absorbs and releases water vapour. Heat is generated and retained during the absorption phase, which makes wool a natural insulator. Used in the home, wool insulation helps to reduce energy costs and prevents the loss of energy to the external environment, thus reducing carbon emissions. |  From Hebridean Landscapes, photo by Heather Potten |
Source: Campaign for Wool