Rock mineral wool insulation is one of those industrial products which saves more energy than is required for its manufacture. The most energy-intensive part of the production is the melting process - at temperatures of above 1500°C diabase rock and recycling materials are turned into lava and then spun as fibres. Energy efficiency has been top priority for many years - it is also the key to reducing other environmental impacts of production such as CO2, NOx and SO2 emissions.