Mineral Wool is Renewable and Recycled
Mineral wool is a renewable material, commonly made from dolomite, basalt, and/or slag. Slag is a waste stream byproduct of steel manufacturing, and dolomite and basalt are igneous (volcanic) rocks that are abundantly naturally re-curring worldwide.
The microscopic fibers within a cross-section of 14 pcf rock wool
A cross-section of a rock wool water retention layer within a living roof
Mineral wool is a lightweight material, so shipping mineral wool uses less fuel than transporting aggregates. Other energy use concerns related to mineral wool are transportation of the base material to the manufacturing plant, and energy used to fire the rock. Most mineral wool manufacturers are actively working to reduce energy usage, reduce reliance on non-renewable energy, and to be transparent in their sustainability efforts via documents such as the NAIMA EPD Transparency Summary.
Sedum reflexum growing on a living roof
Sedum sexangulare and Sedum album growing on an EcoCline living roof
Cradle to Cradle
Some manufacturers have active programs of reclaiming used mineral wool for recycling as a raw material in manufacture of new product. Re-use may also be possible: if the material retains high tensile integrity, intact green roof slabs may be able to be transported and re-used. If the mineral wool exhibits lower tensile integrity, fibers and media can be blended for use in planters or landscape applications or as a potting medium.
A living roof planted with flowering broadleaf sedum plugs
