Sustainable materiels
The sustainability of materials involves at the same time their
impact on health, on the environment and energy consumption.
Their choice depends on different criteria :
- Type and origin of the raw material: is it renewable, recycled, is it perhaps a source of harmful emissions, where does it come from, what is the social context of its production, etc.?
- Embodied energy: how much energy was expended to produce the material, transport it and install it?
- How it is used: this can be the reason for various problems, requiring more or less energy or water, generating more or less waste, etc…
- Polluting content of material: impact at the time of its manufacture, its installation, or its lifetime.
- Lifetime, recycling: some materials need more energy for their manufacture, but have a longer lifetime and are recyclable. An assessment of every material must be made.
- Maintenance needs: frequent maintenance might mean more energy needed, or a risk of problems arising, depending on the products used.
When the construction type has been established, the aesthetic criteria determined and the technical characteristics of the materials decided upon, the ecological quality of the materials must be examined. For equal quality from the technological point of view and depending upon the application and building constraints, the material presenting the least possible impact on the environment and on health will be selected. It is important to note that this choice will not necessarily impact on the financial cost of the construction and that some synthetic materials are very acceptable, if used correctly..
A classification system frequently used in the choice of materials is the NIBE (Nederlands Instituut voor Bouwbiologie en Ecologie; Dutch research organisation specializing in eco-construction methods). The materials and techniques with the highest NIBE coefficient offer the most advantageous ecological properties. The criteria taken into account in the NIBE study are:
- primary energy needs in their manufacture,
- exhaustion of natural resources,
- pollution at the extraction site,
- physical or chemical changes to the molecular chain,
- emission of polluting gases,
- lifetime,
- recycling.
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