LIFE & the Environment

Glass wool manufacture is a continuous process comprising several sequential stages:

  • glass batch material weighing and mixing
  • melting
  • fiberisation of the melt
  • binder application
  • curing
  • cooling
  • product finishing and packaging


The basic glass feedstock materials are a combination of dredged, quarried and processed minerals or manufactured chemicals. A number of forms of post consumer glass, such as bottle cullet and plate glass cullet have also been used traditionally as feedstock materials but this type of material is more difficult to recycle and its use depends heavily on affordable delivered cost and an acceptably low level of contamination.

Unless there are fairly local sources of post consumer cullet, the considerable haulage element has meant that delivered costs are quite high and this, coupled with the contamination levels which exist in most commercially available post consumer cullets, has generally limited the amounts which can be used in glass wool manufacture.

However, in September 2005, Knauf Insulation began a project at their Cwmbran (South Wales) plant to substantially increase the amount of post consumer glass used in their manufacturing process by maximising the amount of waste glass sourced locally and by finding new methods to reduce the level of contamination in the recovered waste glass.

The Project

The project is being carried out with the aid of two partners - the Wales Environment Trust and Filter media Ltd. The project is supported financially by the EU Commission in the form of a grant under the LIFE Environment scheme.

The principal objective of the project is to develop and demonstrate an innovative combination of technologies for recycling of waste glass streams to produce glass wool insulation which, relative to current methods, significantly increases both the proportion and variety of waste glass which is recycled with the following advantages:

  1. a reduction in the need for mineral mining and associated haulage in glass wool manufacture
  2. a reduction in the requirement for glass waste landfill and associated haulage
  3. a reduction in the glass melting energy requirement for glass wool manufacture
  4. a reduction in the a environmental emissions from glass melting in glass wool manufacture


It is difficult to envisage a more environmentally friendly process than one which combines all the above advantages with the ability to produce a product which during its normal life will typically save more than 1000 times the energy used to produce it.

Another Win-Win result from Knauf Insulation.