Finished mineral wool products save far more energy in use than is expended in their manufacture. Also, the ratio of in-use savings to manufacturing emissions of carbon dioxide, the main greenhouse gas, is equally positive. Other greatly reduced air pollutant emissions include SO2, various nitrogen oxides (NOX) and fine particulates.When mineral wool is assessed under rigorous life cycle analysis, it is found to have lower embodied energy than most non-mineral wool products, especially in applications where low density mineral wool products are used.
Increasing amounts of recycled materials are used in the manufacture of mineral wool products.
Within the mineral wool insulation sector, a major contributor to energy savings in recent years has been the use of recycled materials in the production process. Depending on the quality and availability of local supplies, recycled content now makes up 30% to 60% of the raw material input in mineral wool production, as defined by the WRAP Rules of Thumb Guide. In some plants the recycled content is as high as 80%. Owing to improving technology, most of the waste products are recycled back into the production process as well as increasingly using waste from building sites or demolition works to replace raw materials.
Water used in the manufacturing process is generally in a closed circuit system. This has the twofold advantage of reducing fresh water consumption and avoiding the discharge of dirty or polluted water.
Modern packaging technology and the elasticity of modern mineral wool means that the products can often be packed at one ninth of their original volume without negatively affecting the installed thickness. Fewer lorries are required for transportation, thus reducing the environmental impact of transportation. Once unpacked, the product quickly expands back to its original thickness ready for installation.
The following graphics explain the contribution of each life cycle phase to the various indicators. ( Click to enlarge )
When considering LCA results without taking into account operational energy use, the production stage is the most dominating phase during the life cycle. As shown above, use of non-renewable primary energy and impact categories are largely dominated by the production stage or cradle-to-gate (A1-A3), which includes raw materials, binders, transport to plant and production. Within production, energy consumption and associated emissions have the greatest impact.
In detail, modules A1-A3 have the highest non-renewable primary energy demands. When considering the whole life cycle, about 25% of primary energy is used for binder production and another 65% in the consumption of coke, natural gas and oil as energy carriers directly at the plant, including energy carriers for electricity production.
The main generator of global warming potential (GWP) is CO2, with more than 60% resulting from the combustion of all energy carriers at the plant, especially coke in case of stone wool production and natural gas in case of glass wool production, including upstream processes in the electricity supply chain.