The thermal performance of mineral wool is mainly due to prevention of convection by the entrapment of air in the material’s open-cell, woolly matrix. Conduction is reduced because there is very little solid material to provide pathways and the trapped, static air has a low thermal conductivity. Heat transfer is also reduced because the material acts as a physical barrier to radiative processes.
Glass and stone mineral wool insulates by trapping and holding air still. It does not rely on injected gas that can leak and result in a deterioration in thermal performance.
Porous materials such as mineral wool work to control and reduce noise by allowing air movement into the fabric of the material. The fluctuations of air molecules - which form sound waves - move into the body of the mineral wool, where friction between the air particles and the material’s narrow airways cause sound energy to be dissipated as heat.