Modeling of a glass mineral wool process in view of Life Cycle Analysis

In line with the growing concern about the environmental impact of materials in the building sector, Knauf Insulation, a glass wool producer, is performing environmental impact assessment of its products through LCA. Knauf Insulation has several glass wool factories in Europe that produce various products, and for a specific market, the same product can be produced in several factories. As the plants that produce glass wool work with similar pathways, a generic model for LCA usable for every plant and every glass wool product has been designed.
The general principle of glass wool production is the following: the raw materials, sand, limestone, soda ash, borax, sodium carbonate, as well as recycled off-cuts from the production process, are weighed and mixed. Knauf Insulation also uses a large amount of recycled glass (cullet). The mix is sent to a furnace at high temperature (1350°C). The melted material is then fiberized and the binder is added, a process called forming. Knauf Insulation uses a special binder with ECOSE Technology, a new and formaldehyde-free binder. The wool fibers are collected, by suction, on a conveyor belt, and the mattress then goes through the curing oven. For some products a facing is added. Finally the product is compressed and packed.
Specific attention is put in certain LCA aspects, such as allocations procedures, and we have used ISO 14040 and 14044 along with the ILCD handbook as guides during the model development. LCA is performed from raw materials extraction to end-of-life. Nevertheless, the impacts of the insulation system use phase are not included, as they strongly depend on parameters such as construction systems, etc. The functional unit is defined as 1 m3 of specific glass mineral wool product.
The model, implemented in GaBi 6, is made as generic as possible by including, for each step, all the raw materials that can be used in one of the factories as well as all the energy sources. Parameters allow to define the amount of each raw material consumed, therefore the model can be adapted to any factory simply by setting these parameters accordingly. Moreover, the transport distances are also parameters and the origin of the energies (electricity or heat) can also be selected. This simplifies the data collection, since the template is the same for all the factories, it can be supported by data collection tools already existing. A part of the model is dedicated to weighting between factories, so a combination of factories can also be studied. This allows to study products sold on a specific market. The model can also be adapted to almost all Knauf Insulation products by using parameters where necessary: for example, several products have different binder contents, so a parameter defines the amount of binder. As some materials can be recycled between several parts of the process, special attention has been paid to recycling loops inside the model.
The model is flexible enough to be used for Environmental Product Declaration (EPD) as well as for Eco-Design purposes.