Air

ROCKWOOL stone wool achieves its insulating properties by ‘capturing’ the air between the fibers, so that virtually no convection takes place. Because ROCKWOOL insulation only contains natural air and no other gases such as blowing agents, the thermal performance does not change due to gases diffusing from the products – not even if longer periods like the total lifetime of a building are considered.
Insulation products in general limit heat transfer, so that heat remains on the warmer side of the product with only a limited amount of heat being transferred to the colder side. In general, heat can be transferred via conduction, radiation and convection. In ROCKWOOL stone wool products conduction and radiation are the most important ones. Heat conduction is taking place when energy is transferred within a stone wool fibre, whereas radiation is occurring inside the air gaps between the stone wool fibres.