Resource efficiency for insulating materials
Insulation materials play a central role in energetic building renovation. They represent the basic material for a considerable proportion of all the construction activities in Germany. It is important not only to take into account the energy savings from insulation materials during utilisation from the point of view of resource efficiency, but also to analyse the entire product life cycle and therefore to address the aspect of material efficiency. This includes both manufacture and disposal at the end of the life cycle. In this context the insulation effect to be achieved for a structural component continues to be focussed on, and this is then defined as the “functional unit” - as the required function or benefit. The individual insulating materials will now be compared one to the other across the product life cycle through the use of four resource efficiency criteria based on the above:
- Raw material type
- Energy requirement (manufacture)
- CO2 emission (manufacture)
- Entsorgung (end of life)
Data for ecological assessment of the materials has been taken from the construction material database Ökobau.dat 2011 or, if available, from the environmental product declarations (EPDs).1 An insulating effect of U = 0.15 W/m²K, i.e. passive house standard, was defined as the functional unit to be achieved for the existing buildings. It was assumed that a poorly thermal insulating structural component with a k value of 2.3 W/m²K, such as to be found in loft insulation in multi-family housing built in the 60s, is to be retrospectively insulated. The insulating layer thickness required to achieve passive house levels varies according to the thermal insulation properties of the individual insulating materials.
The four resource efficiency criteria for all insulating materials commonly available on the market have been compiled in the following table. Green indicates a low resource consumption, yellow is medium and red is high. Individual insulating materials are listed more than once as a result of the different material characteristics for varying installation situations.
The values vary considerably both for non-renewable primary energy consumption and for greenhouse gas potential. In addition to the differences between the various insulating materials, it can be observed that insulating materials for higher pressure requirements, for example flat roof insulation, generally show a higher energy requirement and higher CO2 emissions than insulating materials with low pressure requirements, such as for loft insulation. This is to do with the fact that a higher material density is required for a higher compressive resistance, i.e. more raw materials are used. A whole series of renewable insulating materials features negative greenhouse gas potential, i.e. they take more CO2 out of the atmosphere during plant growth than is emitted during the subsequent manufacturing process.
In the case of disposal only yellow or red labels have been awarded with one exception, since the currently available options do not by any means possess the resource-protecting potentials of recycling. It is essential that suitable concepts are developed for this since decisions are being made right now about future recyclability during deconstruction from the selection of certain products and fixing methods. Vacuum insulation panels are a positive exception here since at least some of the raw materials are kept within the cycle.